bltn09107

AUTHORS

Xavier Janson Bureau of Economic Ge-ology University of Texas at Austin UniversityStation Box X Austin Texas 78713-8924xavierjansonbegutexasedu

Xavier Janson received his PhD from the Uni-versity of Miami in 2002 where he was a student

Seismic architecture of a LowerCretaceous platform-to-slopesystem Santa Agueda andPoza Rica fields Mexico

in the Comparative Sedimentology LaboratoryHe received a DEA degree (equivalent to an

Xavier Janson Charles Kerans Robert Loucks

MSc degree) from the Institut Franccedilais du

MAlfredoMarhx Carlos Reyes and FranciscoMurguia

Peacutetrole He joined the Reservoir Characteriza-tion Research Laboratory at the Bureau of Eco-nomic Geology of the Jackson School of Geo-sciences at the University of Texas at Austinin 2002 where his current research involvesbuilding 3-D geocellular models and 3-D syn-thetic seismic models from outcrop study tohelp reservoir characterization and seismicinterpretation

Charles Kerans Department of GeologicalSciences University of Texas at Austin Univer-sity Station C1100 Austin Texas 78712-0254

Charlie Kerans is currently the GoldhammerChair of Carbonate Geology at the Departmentof Geological Sciences Jackson School of Geo-sciences University of Texas at Austin Up until2005 he was a senior research scientist at theBureau of Economic Geology at the Universityof Texas where he had worked since 1985 Hisareas of focus are in carbonate sequence stra-tigraphy and reservoir characterization withan emphasis on integrating outcrop analog in-formation for improved understanding of thesubsurface Kerans received his PhD fromCarleton University in Ottawa Canada in 1982where he studied basin analysis and the originof Precambrian carbonates Kerans held aWestern Australian Mining and Petroleum Re-search Institute postdoctoral fellowship be-tween 1982 and 1985 studying Devonian reefcomplexes of the Canning Basin under PhilipPlayford of the Western Australian GeologicalSurvey In 1985 Kerans took a position at theBureau of Economic Geology where he initiatedthe Carbonate Reservoir Characterization Re-

ABSTRACT

Two three-dimensional seismic data sets over the Albian west-ern Golden Lane margin and time-equivalent basinal depositsof Poza Rica field allowed us to investigate the linked architec-ture of a steep-sided carbonate platform (El Abra Formation)and a thick accumulation of redeposited carbonate sediment atthe toe of the slope and in the basinal area (Tamabra Forma-tion) Regional seismic cross sections show that the most ag-grading Albian platform has an eroded platform top a scal-loped margin and a channelized slope that are equivalent to a20-km (124-mi)-wide westward-thinning thick toe-of-slopeapronmade of chaotic contortedmoundedmoderate- to high-amplitude reflections Detailed reflection geometries in theAlbian toe-of-slope and basinal deposits consist of chaotic toshort discontinuous low-amplitude reflection at the toe of theslope of the Golden Lane platform laterally changing to a dis-continuous mounded shingling reflection which ultimatelyturns into high-amplitude parallel reflections We interpret thislateral change to reflect the seismic signature of the changefrom the block- and debris-flowndashdominated toe-of-slope areato debris-flow and concentrated density flow deposits in thebasin that ultimately grade laterally into pelagic deposits On aflattened seismic slice mounded reflections correspond to lo-bate to fan-shaped seismic events several kilometers wide thatare interpreted as a carbonate basin-floor fan Comparison be-tween core and seismic data shows a dominance of debris flowsin the lower two Albian sequences (Albian 1 and Albian 2) thatgrade vertically into more lobate concentrated density flows

search Laboratory at the Bureau in 1988 and hascodirected this research effort with Jerry Luciaof the Bureau up to the present Kerans hasbeen both a domestic and international AAPGdistinguished lecturer He also won the PrattCopyright copy2011 The American Association of Petroleum Geologists All rights reserved

Manuscript received July 6 2009 provisional acceptance October 29 2009 revised manuscript receivedMarch 17 2010 final acceptance June 30 2010DOI10130606301009107

AAPG Bulletin v 95 no 1 (January 2011) pp 105ndash 146 105

Award from AAPG for best article in the AAPGBulletin in 1994 (first author) and in 2005(second author)

Robert Loucks Bureau of Economic Ge-ology University of Texas at Austin UniversityStation Box X Austin Texas 78713-8924

Robert G Loucks is a senior research scientist atthe Bureau of Economic Geology He receivedhis BA degree from the State University of NewYork at Binghamton in 1967 and his PhD fromthe University of Texas at Austin in 1976 Hisgeneral research interests include carbonateand siliciclastic sequence stratigraphy depo-sitional systems diagenesis and reservoircharacterization

M Alfredo Marhx Pemex Exploracion yProduccion Poza Rica Mexico

Alfredo Marhx-Rojano received his MI degreefrom the National University of Mexico (UNAM)in 2010 where he studied energetic subsurfaceresources he received his bachelorrsquos from Na-tional Polytechnic Institute in 1981 with anemphasis on surface geological studies fromSanta Catarina SLP Mexico He joined PetroacuteleosMexicanos (PEMEX) in 1983 His professionaldevelopment includes surface and subsurfacegeology sedimentology and stratigraphicstudies and reservoir development studies

Carlos Reyes Pemex Exploracion y Pro-duccion Poza Rica Mexico

Carlos A Reyes Loacutepez studied his MI degreefrom the National University of Mexico (UNAM)between 1986 and 1989 where he was a stu-dent of physics of reservoirs received his bach-elors from UNAM in 1982 with the ldquoAir andFoam Drillingrdquo He joined Petroacuteleos Mexicanos(PEMEX) in 1983 His professional developmentincludes surface and subsurface reservoir en-gineering studies and he has been team leaderseveral times in onshore and offshore projects

Francisco Murguia Pemex Exploracion yProduccion Poza Rica Mexico

Francisco Murguia is a seismic interpreter and iscurrently in charge of the representation of infor-mation technologies in the Poza RicandashAltamiraAsset of PEMEX Exploration and Production Heis certified in Landmark interactive interpretationsystems with great experience in the use of In-ternet and intranet technologies for access ofdata in the database and the application for the

106 Seismic Architecture Santa Agueda and Po

and turbidites in theupper twoAlbian sequences (Albian 3 andAlbian 4) Seismic data used in this study combined with coreobservations do not support the interpretation of the AlbianTamabra Formation being of shallow-water origin Seismic fea-tures identified as basin-floor fan channel and debris-flow de-posits have a shape and size that are similar to those of otherredeposited basinal carbonate deposits elsewhere The seismicarchitecture shows that the Poza Rica field is a typical exampleof thick accumulation of grainy porous carbonate deposits in abasinal setting This example shows the potential of a large hy-drocarbon accumulation in a tectonically modified stratigraphictrap around shallow-water carbonate platforms

INTRODUCTION

The eastern Golden Lane platform in Central Mexico and itsassociated thick basinal debris apron have been identified sinceits early oil discovery in the 1930s (Barnetche and Illing 1956Viniegra and Castillo-Tejero 1970 Coogan et al 1972 Enos1977Wilson 1990 McFarlan andMenes 1991 Goldhammer1999) Poza Rica field which produces from theAlbian TamabraFormation (Salas 1949) is considered a classic example of athick accumulation of redeposited carbonate sediment adja-cent to a high-relief shallow-water carbonate platform Becauseof the Poza Rica oil field three-dimensional (3-D) and 2-D seis-mic well logs and core are available for detailed study of thearchitecture of the linked platform slope and basinal deposi-tional environment Because little oil or gas production is presentoutside theAlbian ofMexico or the Permian of west Texas fromredeposited deep-water carbonate deposits they have receivedlesser attention than their siliciclastic counterparts

Combining 3-D seismic data over the Golden Lane plat-form and time-equivalent basinal deposits of Poza Rica field aswell as integrating well and core data has allowed us to analyzethe seismic architecture of a shallow-water carbonate-platformtop the platformmargin and the associated steep bypass slopealong with the time-equivalent toe-of-slope basinal apron ofredeposited carbonate The 3-D seismic data reveal not onlythe stratigraphic architecture of various redeposited sedimen-tary bodies but also their relative positions along the deposi-tional profile their dimensions and their morphology

Following a brief regional geologic introduction as well asa short description of the data and methods used in this studythis article discusses first the seismic architecture of a platformslope and basin observed in a composite regional seismic profile

za Rica Fields Mexico

improvement of handling of technical informa-tion in geophysics for the Poza Rica and Chi-contepec groups within PEMEX He has also beena teacher at University Veracruzana since 1986

ACKNOWLEDGEMENTS

This study is part of an integrated reservoircharacterization collaborative project betweenthe Bureau of Economic Geology and Pemex

Second the seismic architecture and morphology of the plat-form top and slopewill be described on the basis of a 3-D seismicdata set over the Santa Agueda field on the Golden Lane plat-form Finally using a second 3-D data set over the Poza Ricafield we will investigate the seismic expression of redepositedcarbonate in the toe-of-slope and basinal area using detailedreflection geometries isochoremaps and seismic attribute slicesas well as seismic-section and well-log and core-cross-sectioncomparison

Exploration Production We thank the directorsof Pemex Exploration and Production for al-lowing us to publish this study We thank ournumerous colleagues at the Bureau of EconomicGeology and at Pemex who have participatedin discussions on these redeposited carbonatesediments The manuscript benefited fromcountless discussions with Ted Playton aboutcarbonate slope We gratefully acknowledge theLandmark Graphics University Grant Programfor providing interpretation software DallasDunlaprsquos help was invaluable in building theLandmark projects Lana Dieterich edited andvastly improved the language of the manuscriptCareful and insightful review by Gregor EberliMike Grammer Jereon Kenter and MarcelloMinzoni made the manuscript more pertinentand focused The Reservoir CharacterizationResearch Laboratory provided funds to coverthe color figure expenses Publication is au-thorized by the Director Bureau of EconomicGeologyThe AAPG Editor thanks the following reviewersfor their work on this paper Gregor P EberliMichael Grammer Jeroen Kenter and MarcelloMinzoni

REGIONAL SETTING

The Santa AguedandashPoza Rica platform-to-basin depositionalsystem is located in the southwestern part of the larger Cre-taceous Golden Lane platform in eastern Mexico The GoldenLane platform is one of several isolated Cretaceous carbonateplatforms that developed on a series of horst blocks in thewestern Gulf of Mexico (GOM) during the Albian (Barnetcheand Illing 1956 Viniegra and Castillo-Tejero 1970 Cooganet al 1972 Enos 1977 Wilson 1990 McFarlan and Menes1991 Goldhammer 1999) During the Early Cretaceous theGolden Lane platform was an ellipsoid-shaped rimmed carbon-ate platform (Figure 1) approximately 150 km (sim93 mi) widealong the long axis in a south-southeast orientation and 70 km(43mi) wide along the short axis (Viniegra and Castillo-Tejero1970 Coogan et al 1972) Santa Agueda field is located onthe southwest-facing margin of the Golden Lane platformwhereas Poza Rica field is located on the adjacent toe of slopeand basin floor approximately 6 km (sim4 mi) basinward of themargin (Viniegra and Castillo-Tejero 1970 Enos 1977)

TheGoldenLaneplatformdevelopedonahorst block formedduring Jurassic rifting which separated the narrow ChicontepecndashMisantla Basin to the west from the GOM to the east (Figures 12) It is underlain by a thick synrift and postrift Jurassic inter-val The base of the Lower Cretaceous consists of the wide-spread basinal carbonate of the lower Tamaulipas Formationoverlain by the argillaceous shale of the Otates Formation thatcorresponds to the Aptian La Pena and Pearsall formations else-where in the GOM (Enos 1977) The upper Aptian to Albianupper Tamaulipas a diachronous formation (Enos 1977) thatcorresponds to retrograding outer-ramp deposits at the base isthe basinal equivalent of the shallow-water carbonate faciesof the El Abra Formation and their slope and toe-of-slope de-bris of the Tamabra Formation during the late Aptian to AlbianBy the end of the Early Cretaceous the isolated Golden Lane

Janson et al 107

Figure 1 (A) Regional paleogeographic map showing the location of the Lower Cretaceous platforms and basins based on Wilson andWard (1993) Lehmann et al (1998) and Kerans (2002) The dark-gray northwest to southeast band indicates the position of the SierraMadre Orientale The red rectangle indicates the location of the map shown in panel B (B) Location of Poza Rica field on the east coast ofMexico (Galicia (2000) (C) Regional schematic cross section of Golden Lane platform Modified from Coogan et al (1972) and Chen et al(2001) Chen et al (2001) and Galicia (2000) figures are republished with permission from the Gulf Coast Association of Geological Societies

108 Seismic Architecture Santa Agueda and Poza Rica Fields Mexico

Figure 2 Stratigraphic column and comparison between age-equivalent Lower Cretaceous formations in the Golden Lane northeast Mexico and Texas areas The section to the left isfrom Enos (1977) The standard chronostratigraphy is from Gradstein et al 1994) The lithostratigraphy and sequence stratigraphy nomenclature for northeast Mexico is from Lehmannet al (1998) The medium-gray triangles pointing up indicate transgressive system tracts the light-gray triangles pointing down indicate highstand system tracts and the dark-grayrectangles indicate lowstand system tracts This study uses the sequence nomenclature established by Loucks et al (in press) shown on the leftmost column The letters in parenthesesassociated with the sequence name indicate the reservoir interval nomenclature used by Pemex Cu1 and Cu2 = Cupido sequences 1 and 2 Co1 to Co5 = Coahuila sequences 1 through 5

Jansonetal

109

Table 1 Poza Rica Field Lithofacies Description

Lithofacies General Description Interpretation

Carbonate breccia Breccias are characterized by large clasts mixed with a range in amount and size of matrixmaterial The deposits are internally chaotic and the percentage of clasts ranges from10 to gt90 The matrix may be dominated by either lime mud or lime sand Clasts seenin core range in size generally from 1 to 20 cm (05ndash8 in) Clasts were derived from boththe platform and the slope Platform clasts are fossil-rich packstones and grainstonescommonly containing predominantly caprinid-type rudists whereas clasts from the slopeare mud rich Platform-derived clasts are much more common than slope-derived clastsindicating the bypass nature of the steep Tuxpan platform slope Breccia deposits with afew grainstones and packstones interspersed show amalgamated thicknesses in coreranging to sim100 m (sim330 ft)

Clast-rich breccia Clast-rich breccias are clast supported and contain very little matrix of either carbonatemud or sand They range to several meters in thickness Contacts between the clasts arecommonly stylotized or sutured and all interclast pores are destroyed

Debris-flow deposits

Grain-rich matrix breccias In grain-rich matrix breccias the matrix between clasts is dominated by carbonate sand-sizeparticles and lesser carbonate mud The amalgamated thickness of this lithofacies canreach 45 m (147 ft) Commonly the grain-rich matrix is highly dolomitized

Debris-flow deposits or modifiedhigh-concentration density flow deposits

Mud-rich matrix breccias Mud-rich matrix breccias may be clast supported with carbonate mud between the clastsor they may be matrix supported with amalgamated thicknesses of as much as 75 m(250 ft) A subordinate amount of carbonate sand can be in the muddy matrix and thematrix is not as commonly dolomitized as are the grain-rich matrix breccias Thefine-grained matrix commonly contains deep-water pelagic microfossils such as globigerinidforaminifers and calcispheres

Mud-rich hyperconcentrated density flowdeposits

Coarse-grained packstoneand grainstone

Coarse-grained grain-dominated packstones and grainstones are predominantly composedof rudist fragments (caprinids and radiolithids) These deposits are homogeneous andhave no visible sedimentary structures or they show upward-fining successions Many ofthese deposits contain minor amounts of mud (lt10) but some of them have severaltens of percent mud A few are capped by thin lime-mud drapes deposited out ofsuspension or have a gravel base containing large caprinid fragments Mineralogy rangesfrom limestone to calcareous dolostone

Hyperconcentrated density flow toconcentrated density flow

Very fine-grained limegrainstone

Relatively thin interval (up to 7 m) of dark fine-grained and finely to thickly laminated limegrainstone can be observed in the Poza Rica deposits Grains are composed of peloidaland skeletal debris Other structures include ripples and cut-and-fill structures

Concentrated flow to turbidity flow

110Seism

icArchitectureSanta

Aguedaand

PozaRica

FieldsMexico

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among

brecciasandsand-rich

depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy

depositionalprocessesThick

intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm

lateraltoandbelowtheTamabraFm

The

intervalsarecharacterized

bywisp

ytocontorted

beddingandthey

commonlycontainsomepercentage

ofterrigenousmud

matrixG

rain

typesinclu

deplanktonicforaminiferaspongespicu

lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy

laminatedsuspensiondepositsSomethin

intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto

neThinterrigenousmudsto

neoccursatseveralintervalw

ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto

fissileshaleThesesedimentsare

composedmainlyof

clayandsomevery

fine-grainedterrigenoussilt

Theseterrigenousmudsto

nesrepresenta

cessationof

carbonatedepositionwhen

theldquocarbonatefactoryrdquo

was

shut

down

ontheadjacent

platform

allowingthem

toaccumulatewithoutb

eing

dilutedby

carbonatedebris

platform built up to 1200 m (3937 ft) of reliefThe Tamabra is overlain by the thin-bedded chalkybasinal limestone of the Turonian Agua Nueva For-mation which is in turn overlain by other UpperCretaceous deep-water facies The El Abra Forma-tion in the Golden Lane is unconformably overlainby Tertiary deposits in the Santa Agueda field Inthe interior of the Golden Lane the Upper Creta-ceous interval is preserved Ultimately the entireCretaceous section is overlain by a thick prograd-ing siliciclastic Tertiary succession deposited in theforeland basin of the Sierra Madre Oriental orog-eny The Golden Lane platform was tilted west-ward during the middle Tertiary tectonic-relatedsubsidence of the GOM and Sierra Madre collision(Coogan et al 1972)

Regional Stratigraphy

Albian and Cenomanian times in the GOM cor-respond to a global eustatic rise (Haq et al 1987)reaching a peak transgression of the Phanerozoic inthe Turonian The long-term rise during middle tolate Albian is consistent with the aggradationalstacking pattern of carbonate platforms and mini-mal influx of siliciclastic sediment into the basinthroughout theGOM(McFarlan andMenes 1991)Lehmann et al (1998) completed a detailed se-quence framework of theAlbian section in anAlbianplatform time equivalent to the Golden Lane plat-form in the Coahuila block and recognized threecomposite sequences (Figure 2) Similarly the Co-manche ShelfndashStuart City system in south Texasis the northward extension of the Albian carbon-ate systems of Mexico (Bebout and Loucks 1977Wilson and Ward 1993 Yurewicz et al 1993Lehmann et al 1998) Loucks et al (in press) syn-thesized stratigraphic data for the 1200 m (3937 ft)of section time equivalent to the Golden Laneplatform on theComanche shelf on the basis of theliterature and original investigations (Figure 2) Theyrecognized four composite sequences (1) latestAptian to early Albian (AptianndashAlbian 1) (2)mid-Albian (Albian 2) (3) mid to late Albian (Albian 3)and (4) latest Albian (Albian 4)

Comparisons between the largerGOMsequenceframeworkandstratigraphyof theTamabraFormation

Janson et al 111

at Poza Rica defined byLoucks et al (in press) as wellas the informal subdivision used by Pemex (F ABC D and ab units) are shown in Figure 2

Lithofacies and Stratigraphic Architecture ofthe El Abra and Tamabra Formations

The Tamabra Formation deep-water deposits con-tain five general lithofacies groups (1) carbonatebreccia (2) coarse-grained carbonate packstone andgrainstone (3) very fine grained lime grainstone(4) lime mudstone or wackestone and (5) terrige-nous mudstone Individual lithofacies groups com-monly stack to form thick amalgamated depositstens of meters thick and they are also interbeddedwith one another Each lithofacies type possesses arange of characteristics as described in Table 1 Theinterpreted depositional mechanism follows Mulder

112 Seismic Architecture Santa Agueda and Poza Rica Fields M

and Alexander (2001) terminology Facies of the ElAbra Formation consist mostly of rudist rudstoneand boundstone and miliolid packstone to wacke-stone as well as karst breccia (Viniegra and Castillo-Tejero 1970 R G Loucks 2004 personal com-munication) For amore extensive description of theGolden Lane platform margin facies see Viniegraand Castillo-Tejero (1970) Enos (1977) and Chenet al (2001) Vertical stacking of facies in theTamabra Formation in Poza Rica field is illustratedin core description of well A (Figures 3 4)

On the basis of modern examples (eg Crevelloand Schlager 1980 Grammer et al 1993) and an-cient examples (Brown and Loucks 1993 Enos andStephens 1993 Playton and Kerans 2002 Jansonet al 2007 Playton 2008 Playton et al in press)we have found a predictive relationship betweenposition within the sequence framework and the

Figure 3 Layout of seismicdata sets available for this studyTwo gray rectangles show loca-tion and extent of the two 3-Dseismic data sets used in thisstudy Thin black lines indicate thelocation of two 2-D seismic linesused to build regional seismicsections of Figures 7 8 Red lines =location of various seismic sec-tions discussed in this article Blueline = location of two regionalsections of Figures 8 9 whereastwo green lines = location of seis-mic sections used for comparisonwith core-based cross sectionsof Figures 21 22 Circle = wellsshown in Figures 4 6 21 22

exico

style of carbonate slope to basin-floor depositionDuring late transgressive systems tract (TST) andearly highstand systems tract (HST) depositionplatforms build steepmargins that becomeunstableand shed the bulk of material that formed themegabreccia complexes In addition platformndash

margin failure at this time sets up a corrugatedplatform margin and tends to channelize debris inthe basin yielding a highly laterally heterogeneousreservoir stratigraphy During the remainder ofhighstand deposition decreased accommodationleads to rapid shedding of carbonate sands along the

Figure 4 Core description of well A From Loucks et al in press

Janson et al 113

length of the margin producing a more homoge-neous strike-continuous blanket of grain-dominatedturbidites Given this simple model the overall strat-igraphic architecture of Poza Rica deposits can besubdivided into four sequences that fit remarkablywell with the stratigraphic architecture recognizedelsewhere in Mexico and south Texas for time-equivalent carbonate deposits described in detailby Loucks et al (in press) (Figure 2)

Loucks et al (in press) interpreted the part ofthe Tamaulipas that occurs at the base of the Ta-mabra Formation as time equivalent with gulfwidetransgression during deposition of the Aptian LaPena Formation elsewhere and deposition of retro-grading carbonate ramps such as the Cupido innorthern Mexico and the Aptian Cow Creek andPearsall Formation in Texas (Goldhammer 1999)It therefore must correspond to the maximumflooding surface (MFS) of their AptianndashAlbian 1sequence

The early Albian was a period dominated re-gionally by vertical aggradation of carbonate plat-forms of the Golden Lane Valles Coahuila andStuart CityndashComanche The vertical aggradationinterval is most prone to development of over-steepened margins and most likely was synchro-nous with deposition of abundant megabreccias inthe basal interval of the Tamabra Formation at PozaRica (Figure 4) Loucks et al (in press) equated thisepisode of platform development with the latestTST to HST of the AptianndashAlbian 1 sequence Thesecond composite sequence Albian 2 is representedby an initial lowstand systems tract (LST) phase ofslow sedimentation followed by transgression TheAlbian upper Glen Rose in Texas and part of themiddle Albian Acatita in the Coahuila area reflectsa period of strong progradation (HST) in the AlbianStuart City margin which is likely to be coevalwith the first period of major grainstone-dominatedhyperconcentrated to concentrated and turbiditedeposition in the Tamabra (Figure 4)

The next widespread event in northern Mex-ico and Texas is the Albian 3 composite sequencewhich reflects a regional change in the style of theStuart City margin from prograding to aggradingand corresponds to the Lehmann et al (1998) Co3sequence in northern Mexico The next debris-


flow interval that overlies the first Albian 2 HSTgrainstone interval (Figure 4) was interpreted byLoucks et al (in press) to represent early TST de-position associated with shelf and shelf-marginaggradation The following grain-dominated hy-perconcentrated to concentrated deposits and tur-bidite deposits are then interpreted as the Albian 3HST The terminal Albian sequence (Albian 4)has a green-gray deep-water shale (at a depth of2012 m [6601 ft] in Figure 4) at the base that is in-terpreted as an LST corresponding to a GOM-wideevent (McFarlan and Menes 1991 Goldhammer1999 Kerans and Loucks 2002) The upper partof the Albian 4 sequence represents a period of ret-rogradation that carries through into the Cenoma-nian Across Texas intrashelf basins form abovethe shallow-water platform top of the Albian 3 se-quence In the Poza Rica area this sequence equateswith deposition of an interval that records con-tracted deposition of reefal breccias and rudist de-bris in an apron close to the shelf margin (Louckset al in press)

DATA AND METHODS

Data Used

Seismic analysis is based on 425 km2 (164 mi2) of3-D seismic data and 50 km (31mi) of 2-D seismicdata Two 3-D seismic surveys (Figures 1 3) coverthe deep-water Poza Rica field and the adjacentGolden Lane platform as well as Santa Agueda fieldIn addition two 2-D seismic lines that connect thetwo 3-D blocks were used to build regional seismicsections (Figure 3)

Seismic data quality is overall fairly good in thePoza Rica data set In the Santa Agueda data setrugged topography at the top of the platform hasinduced severe diffractions of the incoming seis-mic wave energy that have not been entirely re-moved by the migration process In addition be-cause of the strong impedance contrast betweenthe mostly siliciclastic Tertiary formations and theunderlying Cretaceous carbonate platform mostof the incoming acoustic energy has been reflectedback to the surface and only a small part of this

exico

Figure 5 Examples of seismic character across westward margin of the Golden Lane platform in the Santa Agueda field area (A B)Faint steeply inclined reflection suggests a steep-sided margin with bypass slope In C some of the slope reflections are interfingeringwith the platform interior For each of the three seismic sections the dashed line indicates the interpreted top of the carbonate intervalTWT = two-way traveltime

Figure 6 Vertical seismic profile (VSP) data at well X overlain on seismic data Match between VSP and seismic data is generally goodexcept within the reservoir interval where VSP data show one additional reflection compared with that of 3-D seismic data See Figure 3for location of seismic lines and well X MFS = maximum flooding surface TWT = two-way traveltime

Janson et al 115

acoustic energy has been refracted into the under-lying platform As a result only the low-frequencyhigh-energy part of the platform interior seismicresponse is visible in the seismic profile The higherfrequency part of the seismic signal is so contam-inated by destructive diffraction that it is indistin-guishable from noise and therefore unavailable forthe interpretation process In addition seismic ex-pression of the westward slope of the Golden Laneplatform is not constant throughout the data setIn some lines the edge of the platform consists of asteeply inclined faint low-amplitude reflection thatseparates the platform interior from onlapping re-flections against the slope (Figure 5) In other linesupper slope reflections appear to interfinger withplatform interior reflections Given the classic in-terpretation that the Golden Lane platform is anisolated platform (Galicia 2000 Chen et al 2001)a steep platform margin with erosional and bypassslope should be expected Consequently the plat-


form edge is also sometimes difficult to interpret onthe seismic profile

Well-to-Seismic Calibration

Well-to-seismic calibration was performed usingone vertical seismic profile (Figure 6) and addi-tional checkshots in several wells and by gener-ating a limited set of synthetic seismic profiles ofwells with density and sonic well logs Howeverseismicndashwell ties are not optimal because relativelyfew wells with time-depth conversion informationare available as compared with the total numberof wells in the field (gt800) In addition a concen-tration of wells with reliable depth-time conversionlocated on top of the structural high exists wherethe main hydrocarbon production in Poza Ricafield is located As a result a good tie is presentbetween the well-logndashpicked top and the seismic

Figure 7 Vertical seismic section illustrating a good match between well-log-based formation tops and corresponding seismic horizonsin the distal part of Poza Rica field MFS = maximum flooding surface TWT = two-way traveltime

exico

Ta e 2 Seismic Facies

Jansonetal

117

bl

data in thewest part of the field that lie in the higherpart of the structure (Figure 6)

Mapped Horizons

The following horizons were mapped throughoutthe 3-D seismic data in the basin area (eg PozaRica field) (Figure 7) top Albian 4 sequence (topTamabra) top Albian 2 sequence (top BC) and topAlbian 2 MFS (top F) In addition a reflection in-terpreted as the top of the upper Tamaulipas waspicked with moderate confidence The changebetween the Tamabra Formation and the upperTamaulipas Formation is a lateral facies change fromgravity-flow dominated to pelagic dominated anddoes not correspond to a time line It does howevercorrespond to a clear impedance contrast creating amappable diachronous seismic reflection through-out Poza Rica 3-D seismic data According to Enos(1977) regional cross section lateral pinch-out oflimestone-dominated redeposited sediment of theTamabra Formation into pelagic sediment of theupper Tamaulipas is outside the area covered by3-D seismic surveys Loucks et al (in press) showedthat the Tamabra is still more than 130 m (492 ft)thick in awell only 15 km (09mi) landward of thedistal edge of the 3-D seismic data The topAlbian1 sequence (top Tamabra) is a well-marked positivereflection that can bemapped over the entire PozaRica 3-D data set The top Albian 2 MFS (top F)and the top Albian 2 sequence (top BC) are bothmapped at a zero crossing Top Albian 2 (top BC)is a positive-to-negative zero crossing whereas topAlbian 2 MFS (top F) corresponds to a negative-to-positive zero crossing This relationship appearsto be relatively consistent throughout the stud-ied area The upper Tamaulipas horizon is also anegative-to-positive zero-crossing reflection It hasbeen mapped throughout the Poza Rica 3-D seis-mic data set although some difficulty in mappingwith confidence is present in the northeastern partof the data set close to the platform toe of slopewhere seismic reflections become more and morecontorted and discontinuous affecting continuityof top Tamabra Formation reflections The topAlbian 3 surface (top D) and the MFS of the Al-bian 4 sequence were not mapped because se-


quence4 is too thin to be separated from sequence3on seismic data

Definitions of Seismic Facies

Seismic facies are distinguished on the basis of thefollowing seismic reflection characters (1) reflectionconfiguration (2) reflection continuity (3) reflec-tion amplitude and frequency (4) bounding re-lationships that is types(s) of reflection termina-tion or lateral change and (5) external geometryof the reflection package (Mitchum et al 1977Brown and Fisher 1980 Fontaine et al 1987) Inthe Cretaceous interval of interest seven seismicfacies were identified (Table 2) and mapped on re-gional sections (Figures 8 9) Seismic facies inter-pretation in terms of depositional environment isdifficult with seismic alone because sedimentarysuccession deposits in very different depositionalenvironments can lead to similar seismic facies(Fontaine et al 1987 Macurda 1997 Eberli et al2004) However combined with the general mor-phology of the system and regional knowledge ofthe geology cores and well logs a good correlationbetween seismic reflection character and facies orlithology can be achieved

REGIONAL SEISMIC ARCHITECTUREPLATFORM-TO-BASIN CORRELATIONS

Two regional seismic sections from the Santa Aguedaarea (Golden Lane platform) to the Poza Rica ba-sinal area were constructed using a small part of two2-D seismic profiles to connect the two 3-D seismicsurveys (Figures 8 9) These two regional profilesshow the architecture of the Golden Lane platformand slope and Poza Rica toe-of-slope and basin de-posits Several prominent seismic reflections can betraced from the platform area down to the toe-of-slope and basinal area On the basis of well-log cor-relation these reflections are interpreted to corre-spond to the following formation tops (bottom up)(1) top of the substratum (2) top of the PimientaFormation (3) topof theTamabra Formation (4) topof the El Abra Formation (5) top of the MendezFormation and (6) top of the Chicontepec Forma-

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Figure 8 Co es = horizons that correspond to selected formation tops Inclined yellow lines = interpreted small faults Redboxes = locat

mposite regional cross section showing regional stratigraphic organization from the Santa Agueda platform down to the Poza Rica toe-of-slope area Colored thick linion of enlargements shown in Figure 17C D Location of cross section shown in Figure 3 TWT = two-way traveltime

Figur d thick lines = horizons that correspond to selected formation tops Inclined yellow lines = interpreted small faultsLocatio

e 9 Composite regional cross section showing regional stratigraphic organization from the Santa Agueda platform down to the Poza Rica toe-of-slope area Coloren of cross section shown in Figure 3 TWT = two-way traveltime

Figure 10 Three-dimensional perspective view of top Tamabra and top El Abra horizons (light blue) top Pimienta horizon (purple) and top basement horizon (red) Views illustrategeometry of Albian deposits The Albian Tamabra Formation consists of redeposited carbonate debris shed from the Golden Lane platform (right) which stood approximately 1200 m(3937 ft) above the basin floor at the end of the Albian The positive structure affecting the basinal area is due to Tertiary reactivation and uplift TWT = two-way traveltime

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tion These horizons except for the top Tamabraand top El Abra formations have beenmapped onlyon these composite sections These composite re-gional seismic sections show platform-to-basin ar-chitecture through the Santa Agueda field on theGolden Lane platform margin and Poza Rica fieldin the basinal area The most prominent feature onthese two seismic sections is the Golden Laneplatform to the east and its associated wedge ex-tending to the west

The Golden Lane platform accumulated dur-ing most of the Albian mostly by vertical aggrada-tion (Viniegra and Castillo-Tejero 1970 Galicia2000 Chen et al 2001) The platform-to-basinrelief at the end of the Albian is estimated to be upto 1200 m (3937 ft) (given the 600-ms two-waytraveltime [TWT] of relief using a 4000-ms av-erage velocity with no correction for compaction)Figure 10 shows a 3-D view of the El Abra For-mation horizon and the time-equivalent TamabraFormation top horizon (light-blue surface) overly-ing the top Pimienta Formation horizon (purplesurface) and the basement horst block (red sur-face) The Golden Lane platform consists of a thicksuccession of mostly chaotic contorted reflectionscapped by several discontinuous mounded high-amplitude reflections The base of the Cretaceousplatform is represented by a semicontinuous high-amplitude reflection that is interpreted to correlatewith the top of the Jurassic Pimienta Formation inthe basinal area Inclined high-amplitude semicon-tinuous reflections dipping toward the northeastrepresent the transition between the topographicrim of the Golden Lane platform into the platforminterior The relief between the Golden Lane rimand the platform interior is more than 50 msequating to 75m (246 ft) ormore depending on theacoustic velocity of these carbonate sediments Givencurrent data whether this relief represents a truetransition from an elevated carbonate margin to adeeper platform interior or whether it is simply theresult of differential compaction between the ce-mented margin and the muddier platform interioris unknown

The westward slope of the platform into theMislantandashChicontepec Basin is represented on seis-mic data by (1) onlapping reflections (2) discon-


tinuous inclined reflections or (3) (occasionally)continuous inclined high-amplitude reflectionsThese reflections which can be mapped using thePozaRica 3-D survey correspond to the topTamabraFormation which was interpreted from the well tieThe interval between the Pimienta and top ElAbrandashTamabra horizon comprises the Albian section thatin the basin includes both the Tamabra Formation(redeposited carbonate sediment) and the upperTamaulipas Formation (pelagic sediment)

The basement horst under Poza Rica field isseismically imaged by a chaotic low-amplitude re-flection cappedby a semicontinuous high-amplitudereflection that becomes difficult to trace accuratelybelow2s (TWT)Viniegra andCastillo-Tejero (1970)located another basement horst below the GoldenLane platform on the basis of a single core but itcannot be clearly seen on available seismic dataBetween the basement high under Poza Rica fieldand the one underlying the Golden Lane platformthe topographic low is filled with Jurassic sedi-ment (Salas 1949 Viniegra and Castillo-Tejero1970 Enos 1977) that corresponds to semicontin-uous moderate- to high-amplitude reflections inregional composite seismic sections (below the bluehorizon in Figures 8 9) These reflections seem toonlap on the basement high

Overlying the Albian interval several high-amplitude continuous reflections in the basinalarea represent the Upper Cretaceous AguaNuevaSan Felipe andMendez formations which consist ofpelagic chalk and shaly deposits A series of eastward-inclined semicontinuous low-amplitude reflec-tions with numerous truncation geometries rep-resent the eastward progradation of Tertiary silici-clastic sediments associatedwith the foreland basinfill of the Sierra Madre Oriental (Soegaard et al2003) The high-amplitude continuous reflectioneasily recognized on seismic data (yellow horizonin Figures 8 9) correlates to the top of the Chicon-tepec Formation inwell-log and core data (Figure 6)These Tertiary reflections onlap and drape over re-lief of the Golden Lane platform

Detailed seismic architecture of the GoldenLane platform in the Santa Agueda field area andtoe-of-slope and basin deposits in the Poza Ricafield area will be described in the next sections

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DETAILED SEISMIC ARCHITECTURE

Santa Agueda Platform

Platform TopBecause of the high-impedance contrast betweenplatform carbonates and overlying Tertiary silici-clastic deposits few if any reflections can be carriedfrom the platform interior to the slope The plat-form top shows high-amplitude mounded semi-continuous reflections with abundant diffractionhyperbolas (seismic facies 7 inTable 2) (Figure 11)The rugged topography imaged by the 3-D seis-

mic surveys is most likely produced by intensivekarstification of the Golden Lane platform topKarstification of the top of the Golden Lane plat-form has been known about since discovery ofthe Golden Lane margin reservoirs (Salas 1949)In addition core observations in Santa Aguedafield by the authors reveal a range of karst-relateddeposits such as laminated terrigenous sedimentinterpreted as cave fill and a range of carbonatebreccia from crackle to mosaic to chaotic inter-preted as cave breccia (Viniegra and Castillo-Tejero 1970 Coogan et al 1972 Janson et al2004)

Figure 11 (Top) Uninter-preted seismic section throughthe Golden Lane platform (Mid-dle) Interpreted seismic sectionPurple line = top of El Abra For-mation Blue line = top of Pi-mienta Formation Dashed greenline = intersection with amplitudetime slice displayed in Figures 1315 The yellow dashed linesrepresent the interpreted top ofthe platform below the El Abrahorizon Red box = location ofenlargement presented below(Bottom) Enlarged view of seis-mic expression of the top of theEl Abra Formation This irregularsurface shows relief up to 200 m(656 ft) (using a 400-ms seis-mic velocity) which is interpretedas a post-Albian karst featureon the platform top TWT = two-way traveltime

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The platform interior area is dominated by cha-otic seismic facies (seismic facies 6 in Table 2)Within the platform interior chaotic one other in-terval of high-amplitude mounded reflections canbe observed On the basis of the interpretation ofsimilar seismic facies on top of the platform thisother interval could indicate an older phase of plat-form karstification (see Figures 8 9 11 Figure 12shows a 3-D view of the top of the El Abra For-mation horizon) This very irregular topography isinterpreted as having resulted from a major karst


event at the end of theAlbian (Viniegra andCastillo-Tejero 1970 Coogan et al 1972 Janson et al2004) Seismic reflection geometries indicatepossible large-scale erosion and dissolution of theplatform top and margin (Figure 13) Several deepdepressions in the surface are interpreted as sink-holes related to karstification of the platform top

The edge of the Golden Lane platform in theSanta Agueda 3-D seismic survey is not well de-fined everywhere but it wasmapped at the changefrom high-amplitude continuous reflections of the

Figure 12 Perspective view ofthe time structure map of the topEl Abra Formation horizon Coloron horizon represents two-waytraveltime

Figure 13 Amplitude time slice overGolden Lane platform Yellow line =interpreted platform margin Greendashed line = location of Figure 11High-amplitude chaotic response (bluecircle) is interpreted as karstified topof the platform Large reentrants thatscallop the platform margin might havebeen created by large-scale collapse ormay result from post-Albian erosionof the platform

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overlying onlapping Tertiary siliciclastic sedimentand highly discontinuous reflections of the platformtop This change in reflection character as seen ontime slices shows that the margin is not rectilinear

but sinuous (Figure 13) with several large reen-trants These reentrants can be interpreted as large-scale margin-collapse features (Mullins et al 1986Bosellini 2001) that have scalloped the slope could

Figure 14 (A) Seismic section along strike of Golden Lane platform Yellow green and blue horizons = top of Mendez top of El Abraand top of Pimienta formations respectively Red and yellow boxes = location of enlargements shown in panels B and C (B) Enlargedview showing two large erosive channels that cut through upper Albian slope (C) In enlarged view blue arrows point to reflectiongeometries interpreted to be older erosive channels on the slope of the Golden Lane platform TWT = two-way traveltime

Figure 15 Amplitude timeslice over Golden Lane platformYellow line = interpreted plat-form margin Green dashed line =location of Figure 11 High-amplitude chaotic response (bluecircle) is interpreted as karstifiedtop of the platform Orange ar-rows point to possible large can-yons on the Golden Lane plat-form slope

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Figure 16 Three strike-parallel sections across the Poza Rica data set For eachsection the seismic section with horizons is shown (top) along with the line drawing(bottom) of the Tamabra interval to illustrate reflection geometries Panel A isthe most landward section near the toe of slope of the Golden Lane platform Panel Bis located in the middle of the Poza Rica field Panel C is the most distal sectionRed arrow = location of regional dip-parallel cross section of Figures 8 9 Yellowbox = position of enlargement shown in Figure 17A B TWT = two-way traveltime


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have sourced some of the debris accumulation ob-served in Poza Rica field and could also have servedas preferential paths for sediment shedding fromthe platform top

Platform SlopeStrike-parallel vertical seismic sections through theslope reveal numerous concave features that trun-cate underlying reflections (Figure 14) On timeslices these features form indentations on the upperbasin-facing slope but are absent in the platforminterior-facing slope (Figure 15) These erosionalfeatures are interpreted as erosional channels thatcut the slope The size of these channels ranges from300 to 600 m (984ndash1969 ft) in width and between30 and 80 ms TWT in depth This traveltime cor-responds to a depth of 60 to 160 m (196ndash525 ft)using a seismic velocity of 4000 ms for time-to-depth conversion These channels are sometimesvertically stacked and their dimensions resemblethose of published carbonate slope channels (Mullinsand Cook 1986 Eberli et al 2004 Phelps andKerans 2007) and siliciclastic slope channels (Floodand Damuth 1987 Clark et al 1992 Waltham2008 Wood and Mize-Spansky 2009)

None of these canyons has the depth or widthrequired to be the single major submarine canyonfeeding the entire Tamabra interval A regionalline-source-feeding mechanism for platform-to-basin sediment is therefore probably associatedwith a local point-source feed such as in themodernBahamas slope (Mullins et al 1984)

Poza Rica Toe-of-Slope and Basin Deposits

Reflection Geometries

Toe of Slope and Basin Poza Rica Field AreaRegional dip-oriented cross sections (Figures 8 9)show a change in reflection character from the plat-form toe of slope to the basinal area Figure 16 il-lustrates the reflection character of three strike sec-tions in various positions away from the slope intothe basin In the proximal part of the Poza Rica area(Figure 16A) reflections show wide mounded fea-tures associated withmultiple small-scale faults Thetoe of slope of the Golden Lane platform is char-


acterized by wavy contorted to chaotic reflectionsFarther basinward seismic facieswithin theTamabrainterval consist of contorted and mounded low-amplitude reflections (seismic facies 3 in Table 1)Internal reflection geometries within this seismicfacies are complex Themost distal part of the PozaRica area (Figure 16C) shows more continuousundulating high-amplitude reflections whereasin the central part (Figure 16B) reflections are oflower amplitude and have more mounded wavyand shingled geometries

Figure 17 shows enlarged displays of the Tamabrainterval illustrating complex reflection geometriesin both strike (Figure 17AndashC) and dip directions(Figure 17D) Reflection terminations consist ofdownlap onlap toplap and truncation The shapeof reflections ranges from horizontal inclinedand shingling to mounded and channel shapedIn the proximal part of the dip-oriented section(Figure 17D) near the toe of slope of the GoldenLane platform reflections are short and discontin-uous The base of the Tamabra interval shows nu-merous short discontinuous concave and convexreflections whereas the upper part of the Tamabrainterval shows more continuous higher amplitudeconvex reflections Farther downdip reflections aremore continuous and higher amplitude on the dip-parallel section Shorter reflections onlap ontomorecontinuous concave reflections An apparent gen-eral shingle to the northeast is mainly caused bytectonic uplift of the underlying basement (seefollowing paragraph)

Figure 17A B shows an enlargement of reflec-tion geometries seen on the larger strike-parallelcross section in Figure 16 Similar to the dip-parallelsection the base of the Tamabra shows numerousshort discontinuous concave reflections whereasthe upper third of the interval shows more con-tinuous higher amplitude reflections A few lobate(concave-upward) packages of reflection can be dis-tinguished but overall the reflections are difficultto follow more than 500 m (1640 ft) laterally Themore distal strike-parallel section (Figure 17B) hasoverall higher amplitudes and more continuousreflections are seen Figure 17B also shows two clearconcave-upward reflections with lateral shingling(green and yellow arrows) that are approximately 1

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Figure 17 Enlargement of part of the strike-parallel (AndashC) and dip-parallel (D) seismic sections shown in Figures 8 16 Reflection terminations and reflection geometries within theTamabra interval are also shown Note lack of lateral continuity and complex relationship between reflections Purple orange and blue lines correspond to the top of the Tamabraupper Tamaulipas and Pimienta formations respectively Thin orange lines = positive amplitude reflections whereas green lines = negative amplitude reflections Green and yellowarrows in panel B show concave-upward reflections with lateral shingling The blue arrows indicate a convex-upward reflection TWT = two-way traveltime

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127

Figure 18 Flattened seismic sections Yellow green orange blue and red horizons = top of Chicontepec Tamabra (top Albian 4sequence) upper Tamaulipas Pimienta formations and the basement respectively (A) Regional seismic section of Figure 8 is flattenedon the Pimienta Formation horizon (B C) Flattened dip-parallel seismic section (D) Flattened strike-parallel section Bold dashed lineshighlight restored reflection geometries forming shingling mounded and lobate reflection geometry TWT = two-way traveltime


Janson et al 129


and 17 km (sim062 and 106 mi) wide respectivelyIn the eastern part of the section shorter reflectionsonlap onto a continuous high-amplitude faintlyconvex reflection (blue arrows on Figure 17B)

Reconstructed GeometriesSo that predeformation and tilting of the Creta-ceous depositional system can be reconstructedseismic data need to be flattened on a chronostrati-graphically consistent surface that has as little pa-leotopography as possible The base of the TamabraFormation is a lithostratigraphic change from gravity-flowdeposits anddeep-water carbonatemuddepositsof the upper Tamaulipas Formation This lithostrati-graphic surface cannot be used for flattening Thedata set was flattened on the Pimienta Formationhorizon which corresponds to the top of an argil-laceous and deep-water mudstone that is inter-preted to be a consistent chronostratigraphic surfacewith no significant topography

The flattened seismic section which displaysreflection geometries that are interpreted to rep-resent overall original geometries at the time ofdeposition (Figure 18) shows westward thinningof the Tamabra interval In all three dip-orientedsections (Figure 18AndashC) proximal parts of the sec-tions showmore discontinuous mounded reflectionthan do the distal parts The strike-oriented section(Figure 18D) shows convex-upward reflection ge-ometries associated with a few shingling reflectionsOverall the flattening data show more lobate re-flection with onlap of shorter reflection onto thelobate reflections

Some of the shingling of the basement hightopography has previously been interpreted as evi-dence of shallow-water carbonates (Horbury et al2004) On the flattened regional cross section(Figure 18A) their reconstructed geometry couldalternatively be interpreted as shingling reflections

created by lateral compensation of lobate gravity-flow deposits

Interpretation of Reflection GeometriesThe blocky discontinuous short reflections ob-served at the toe of slope of the Golden Lane plat-form are interpreted as toe-of-slope slumps andcoarse debris-flow deposits with large blocks (Mullinset al 1986 Grammer et al 1993 Lomando et al1995 Janson 2002) Similar reflection character isalso observed at the base of the Tamabra Forma-tion which consists dominantly of thick carbonatebreccia interpreted in core and well-log interpre-tation as massive debris-flow deposits (Figure 4)(Loucks et al in press)More continuous moundedto lensoid convex-upward reflections associatedwith lateral shingling in both dip and strike sectionsare interpreted as large fan deposits of concen-trated density flows and turbidites In strike sec-tion obliquely shingled reflections are interpretedas lateral accretion of stacked and amalgamateddebris-flow deposits andor concentrated gravity-flow deposits (Eberli et al 2004) In dip-parallelsections shingled reflections associated with fandeposits have been interpreted as channel-backfilling (Betzler et al 1999 Eberli et al 2004Savary and Ferry 2004)

Isochore Map

Albian 1 to Albian 4 Sequence (Tamabra to Upper TamaulipasFormations) MapFigure 19A shows a seismic-based isochore mapand a well-log-based isochore map between the topTamabra horizon and the top upper TamaulipashorizonThe twomaps showoverall southwestwardthinning of the entire Tamabra section The thickestinterval is located in the northeast corner of the3-D data set close to the Golden Lane platform

Figure 19 Isochore maps for different intervals within the Tamabra Formation based on core data (left) and seismic data (right)(A) Two maps illustrating southwestward thinning of the entire Albian Tamabra Formation interval Panels B and C show intra-Tamabra interval thickness variation (B) Isochore map between top of Albian 2 sequence (top BC) and maximum flooding surface (MFS)of Albian 2 sequence (top F) This interval shows thickness variations interpreted as dip-elongated aprons superimposed on a generalsouthwestern thinning trend (C) Isochore map of Albian 3 and Albian 4 sequences (between top of Tamabra horizon and Albian 2 top BChorizon) Two top sequences could not be separated on seismic data Well-log-based maps on the left show only the Albian 3 sequenceWhite dashed line on seismic isochore maps = area of well-log-based map on left

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Figure 20 Seismic attribute slices of the 3-D seismic data set flattened on the top Tamabra Formation (top Albian 4) horizon Slicelocations are progressively deeper left to right The uppermost slice (left) is located 12 ms below the Tamabra horizon and correspondsapproximately to the Albian 3 and Albian 4 sequences The middle slice is located 44 ms below the Tamabra horizon corresponds ap-proximately to the Albian 2 sequence The deepest slice (right) is located 68 ms below the Tamabra horizon and corresponds ap-proximately to the Albian 1 sequence (A interval) The orange area corresponds to the intersection between the time slice and the upperTamaulipas Formation horizon The Albian interval is located on the right side of the orange area (A) Slice through the seismic amplitudevolume Yellow dashed lines = lobate shape (BndashD) Slices through inverted acoustic impedance volume instantaneous frequency volumeand coherence volume respectively Thick dashed line = lobate shapes identified on each slice whereas thin dashed line = shape identifiedon the seismic amplitude slice for reference


Figure 20 Continued

In themore proximal position where the Tamabrais the thickest a significant along-strike thicknessvariability could indicate that some preferentialpath exists for off-platform sediment shedding andgravity-flow deposits

Albian 2 Isochore (Top FndashTop BC) MapThis interval encompasses the Albian 2 TST andAlbian 2 HST As identified on the well-log-basedisochore map (Figure 19B left) this interval is char-acterized by southward thinning The basal interval

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shows significant thickness variation interpreted asdepositional geometries dominated by lobate de-posits In addition the northwest corner shows thickintervals that are elongated along the northeast-southwest This pattern is interpreted as large de-bris aprons partly located outside the study areaseparated by deeper channels at the toe of slope ofthe Golden Lane platform

Albian 3 and Albian 4 Isochore (Top TamabrandashTop BC) MapThis interval includes both Albian 3 and Albian 4sequences Because of the seismic resolution of thedata set where the Albian 4 sequence is repre-sented by one reflection this isochore map repre-sents combined thickness variations of the Albian 3and Albian 4 sequences (Figure 19C) The isochoremap shows a more complex thickness distributionthan the underlying interval and the isochore mapshows a heterogeneous thickness variation similar tothat seen on the regional seismic section (Figures 89) Southwestward thinning is still present but it issubtler The rapid lateral thickness variations canbe interpreted as evidence of juxtaposition of dif-ferent depositional environments such as channeland lobes The thicker interval in this case is lo-cated in the northeast corner of the data set andis isolated from the platform toe of slope Thisisolated thick could be interpreted as a large fancomplex suggesting a change in the source of debrisand in transport direction

Seismic Attribute AnalysesThe 3-D seismic data set was flattened using thetop Tamabra horizon to investigate the horizontaldistribution of various seismic attributes in horizon-parallel seismic slices For each flattened cube andfor each attribute three time slices were presentedthat intersect Albian 3 and Albian 4 (shallowest)Albian 2 and Albian 1 (deepest) sequences respec-tively (Figure 20)

Flattened AmplitudeFigure 20A shows three time slices of the flattenedseismic amplitude 3-D data set The proximal partof the shallowest slice (Albian 3 and Albian 4 se-quences) showsmostly chaotic reflections whereasthe more distal part shows large lobate shapes cut


by rectilinear features that could be interpreted asfans and channels The middle slice (Albian 2 se-quence) shows a similar reflection character dis-tribution but with a much narrower proximal zonewith chaotic reflections

The lobate amplitude features seen on the twoupper slices are approximately 15 to 4 km (sim09ndash25 mi) wide Their fanlike shape is coherent withsediment coming from the adjacent Golden LaneThe uppermost slice (Albian 3 and Albian 4 se-quences) shows lobes smaller than those of themiddle slice (Albian 2)

The Albian slice shows more continuous re-flection with fewer lobate features and a more cha-otic amplitude distribution than seen in the twoshallower slices Small fanlike seismic geometriescan be observed in the northern area

Acoustic Impedance InversionThe inverted acoustic impedance data (Figure 20B)were flattened on the top Pimienta horizon Timeslices of this flattened data set show lobate featuressimilar to those seen on amplitude slices The in-verted acoustic impedance cube is a proxy for po-rosity The shallowest seismic slice shows large lo-bate areas of low impedance that correspondroughly to the lobate area on the amplitude sliceLowest impedance values are mostly within the lo-bate shape identified on the amplitude slice Thelower slice shows less low-impedance area Thenorthern areas that were showing lobate shapeson the amplitude display consist mostly of high-impedance values showing a faint lobate shape Ageneral increase in overall impedance values and adecrease in lateral heterogeneities in impedanceseem to be occurring in the Albian 2 slice

FrequencyThe frequency seismic attribute (Figure 20C) is agood indicator of complex reflector geometriesthat are below seismic resolution (Robertson andNogami 1984Taner et al 1994Chen andSydney1997 Taner 2001) All slices show rapidly chang-ing frequencies in the northeast at the toe of slopeof the Golden Lane platform Such frequency tun-ingmay indicate complex reflector geometries suchas slumps large blocks and coarse debris flows

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Figure 21 Comparison of dip-parallel core-based cross sections (A B) with seismic amplitude (C) and inverted acoustic impedance (D)sections Core-based cross section taken from Loucks et al (in press) Cross section in panel B was scaled to have a dimensioncomparable to that of the seismic section shown in panels C and D Both cross section data are flattened on the maximum floodingsurface (MFS) of the Albian 2 sequence (top F) Green yellow and blue horizons on both cross sections and seismic sections = top ofAlbian 4 (top Tamabra Formation) top of Albian 2 (top BC) and MFS of Albian 2 (top F) respectively For location of the cored well andseismic section see Figure 3 TWT = two-way traveltime

Janson et al 135

More distally the frequency display shows severallobate and arched shapes of relatively constant fre-quency that correspond to the lobes identified onthe amplitude slices The rectilinear feature cuttingone of the southern lobes is particularly clear withits frequency values higher than those of the ad-jacent lobate area The deepest slice displays amorechaotic distribution of frequency indicating com-plex reflector distribution

CoherenceThe coherence attribute indicates the amount ofsimilarity between adjacent traces It is a good in-dicator of the complexities of reflection geome-tries and enhances small-scale and subtle features(Bahorich and Farmer 1995 Chen and Sydney1997 Taner 2001 Massaferro et al 2004) Sev-eral linear features visible on coherence slices(Figure 20D) are interpreted as faults In all threeslices the area close to the Golden Lane platformhas a low coherence indicating complex reflectiongeometries whereas the distal part shows morelaterally continuous reflections (lighter color in thecoherency display) Several lobate features thatmatch the one observed in the other attribute mapcan be observed in the Albian 2 Albian 3 andAlbian 4 slices

Interpretation of Seismic SlicesSeismic slices from various seismic attributes showa common pattern

bull The proximal area close to the Golden Laneplatformhas discontinuous complex reflectionswhereas the more distal area shows more con-tinuous higher amplitude reflections

bull In theAlbian2Albian3 andAlbian4 slicesmorecontinuous reflections form large lobate shapes

bull The Albian 1 slice has consistently more chaoticdiscontinuous complex reflection geometries

Given the toe-of-slope and basinal settings ofthe Poza Rica area (Enos 1977) we interpreted lo-bate shapes with more continuous reflections aslarge probably basin-floor-fan deposits of hyper-concentrated density flows and turbidites Recti-linear features associated with the lobate shape


are interpreted as channels that feed or erode lo-bate deposits These lobate shapes are 1 to 5 km(06ndash31 mi) wide and their geometries are con-sistent with a platform source to the east

The more discontinuous complex reflectionarea is interpreted as slumps with large blocks andcoarse debris-flow deposits that create a complexdistribution of impedance and diffraction of seis-mic waves resulting in complex discontinuousreflection geometries This reflection character isseen mostly in the proximal area near the GoldenLane platform and in the Albian 1 sequence whichis dominated by debris-flow deposits (Figure 4)(Loucks et al in press)

Comparison of Seismic and Lithofacies Core-Based SectionFigure 21 compares a seismic cross section with acore-based geologic cross section along the generaldip direction of Poza Rica field of Loucks et al(in press) (Figure 21A B) The seismic amplitudesection (Figure 21C) the inverted acoustic imped-ance section (Figure 21D) and the core section areflattened on the top Albian 2 sequence (top BC)horizon

Characteristics and distribution of the seismicfacies can be compared with those of the litho-faciesmapped on the core-based cross section Theupper Albian sequence 4 which consists of a thinstack of hyperconcentrated density flows concen-trated density flows and turbidite deposits (Mulderand Alexander 2001) and underlying lime mudand suspension deposits is containedwithin the topTamabra Formation strong positive reflection (be-low the green horizon) The Albian 3 sequencecorresponds to the reflection above the top of theAlbian 2 sequence (yellow horizon) These reflec-tions are relatively continuous and almost parallelthe top of the Tamabra Formation The two inter-vals show a similar acoustic-impedance signatureAlbian 2 sequences TST and HST are located be-tween the Albian 2 sequence (yellow horizon) andthe MFS of the Albian 2 sequence (blue horizon)This interval is characterized by an upper part witha higher amplitude semicontinuous reflection thanits base Similarly acoustic impedance is lower atthe top of this interval than near the base althoughthe difference is more pronounced in the proximal

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part of the section than in the distal part This seismicreflection seems to correspond to the difference be-tween a hyperconcentrated density flowndashdominatedHST and a tighter debris-flowndashdominated TST TheAlbian 1 sequence and the Albian 2 LST correspond

to seismic reflections between the upper TamaulipasFormation horizon (orange) and the MFS of theAlbian 2 sequence (blue horizon) In core this in-terval is dominated by stacked debris-flow depositsThe reflections are more continuous and have a

Figure 22 Comparison of strike-parallel core-based cross sections (A B) with seismic amplitude (C) and inverted acoustic impedance (D)sections The core-based cross section taken from Loucks et al (in press) The cross section in panel B was scaled to have a dimensioncomparable to that of seismic section shown in panels C and D Both cross section data are flattened on the maximum flooding surface (MFS)of Albian 2 sequence (top F) Green yellow and blue horizons on both cross section and seismic sections = top of Albian 4 (top TamabraFormation) top of Albian 2 (top BC) and MFS of Albian 2 (top F) respectively For location of the cored well and seismic section see Figure 3

Janson et al 137

higher amplitude in the central part of the sectionthan in themore distal and proximal parts In strike-oriented sections (Figure 22) the northwestern partof the cross section shows the same seismic signa-ture as the one described for the dip-oriented sectionHowever the upper part of the Tamabra Formation(Albian 2 through Albian 4 sequences) shows a de-crease in acoustic impedance toward the southeastthat cannot be explained by the geologic informa-tion depicted on the core-based cross section

RESULTS AND DISCUSSION

Results

The Golden Lane platform top in Santa Aguedafield shows indications of pervasive and maturekarst The upper slope shows numerous reentrantsthat can be interpreted as margin collapse whereasthe lower slope shows numerous channels prob-ably created by the continuous export of sedimentfrom the platform top to the basinal area Becausethe toe-of-slope area consistently shows a chaoticseismic facies it is interpreted as slump and coarsedebris-flow deposits In the distal area the base ofthe Tamabra Formation shows similar seismic fa-cies whereas the upper part has more continuouslobate to lensoid reflections that have a vague fan-like distribution on the seismic slice The isochoremap of the two upper sequences also shows irreg-ular thickness distribution associated with increas-ing amounts of hyperconcentrated density flow de-posits Seismic reflection architecture matches coreand well-log interpretation relatively well Albian 1and Albian 2 sequences are dominated by massivedebris-flow deposits and show low-amplitude dis-continuous reflections whereas the Albian 3 andAlbian 4 sequences display frequent thinner hyper-concentrated density flow deposits as well as loweramplitude more continuous reflections

Discussion

Poza Rica Toe of Slope Versus Lowstand Isolated PlatformsThe depositional environment of the Tamabra For-mation has historically been the topic of discussion


on the shallow- or deep-water depositional settingof the Tamabra Formation (Barnetche and Illing1956 Bebout et al 1969 Viniegra and Castillo-Tejero 1970Cooganet al 1972Enos 1977WilsonandWard 1993) Since theEnos (1977) study and itsinterpretation as deep-water deposits the TamabraFormation is commonly regarded as the classic deep-water redeposited carbonate system However re-cently the shallow-water origin of the Tamabra For-mation was reintroduced by Horbury et al (2004)on the basis of core observation and analysis of 3-Dseismic data over Poza Rica field Seismic data areunambiguous in showing the low structural positionof Poza Rica field some 700 to 1200 m (2297ndash3937 ft) below the top of the Golden Lane platform(Rockwell and Garcia Rojas 1953) No indicationexists on the seismic data of major prendashTamabraFormation or synndashTamabra Formation uplift of thebasement block underlying Poza Rica field with amagnitude required for bringing these deposits in theshallowwater A second unambiguous relationshipis the formation of the Albian carbonate westward-tapering wedge which is thickest adjacent to theplatform margin gradually becoming 025 timesthe thickness at the crest of the field (Figures 7 818) This trend in thickness supports an interpre-tation of an easterly source of sediments at PozaRica Such a thickness trend could be created bybackstepping the shallow-water carbonate platformonto the underlying basement high although itwould then conflict with the Horbury et al (2004)interpretation of shingling reflection as platformprogradation Moreover if a shallow-water carbon-ate platform had initiated on the basement highand was backstepping andor drowning thereshould be a symmetrical geometry on both sidesof the basement high In addition circular seismicanomalies that are interpreted as karst by Horburyet al (2004) are numerous on the coherence mapthroughout the Poza RicandashTamabra interval How-ever these anomalies are concentrated near the toeof slope of the Golden Lane platform (Figure 20)and not on the basement high where shallowwaterhas been invoked in the Horbury et al (2004)model We interpret these anomalies as the resultof seismic diffraction instead of karst features Inaddition the fan-shaped feature identified on the

exico

Table 3 Carbonate Slope and Basin Attribute Table

Authors LocationAge

(system series stage)

ApproximateSlope

Height (m)

ApproximateSlope

Angle (deg)Distal DebrisPosition

Distal DebrisExtent (km)

Channels(width)

Fan (width [W]and length [L])

Enos 1977 this study Golden Lane Mexico Lower CretaceousAlbian

1500 30 Toe of slopebasin 30 sim100ndash400 m 1ndash4 km(W and L)

Ineson and Surlik 1995 Greenland Cambrian 1000 30 Toe of slopebasin 70 NoSurlik and Ineson 1992 Greenland Silurian 1000 45 Toe of slopebasin 50 NoCook et al 1972 Srivastavaet al 1972 Whalen et al2000

Alberta Basin AlbertaCanada

Upper DevonianFrasnian

200 20 Toe of slope 3 No

Playford 1980 Playford et al1989 George et al 1995

Canning BasinNorthwest Australia


200 90 Basin 2 No

Collins et al 2006 Tengiz field Kazakhstan CarboniferousViseacutean-Serpukhovian

1200 35 Lower slopetoeof slope

5 sim200ndash500 m No

Rigby 1958 Lawson 1989Brown and Loucks 1993Playton 2008

Permian Basin westTexas

Permian GuadalupianCapitanian

700 70 Basin 15 200ndash3000 m 1ndash3 km(W and L)

Bosellini 1984 Harris 1994 Dolomites northern Italy Middle to Upper Triassic 750 35 Slope 2ndash4 Savary and Ferry 2004 Vocontian Basin France Lower Cretaceous

Barremian600 2ndash5 Basin 35 200ndash500 m 5 (W) times

20 (L) kmFernandez-Mendiola et al1993

Cantabrian Basin Spain Cretaceous Aptian toCenomanian

250 35 Toe of slopebasin 20 50ndash200 m

Bosellini et al 1993Borgomano 2000Bosellini 2001

Apulia platform Italy Cretaceous Aptian toCenomanian

450 30 Toe of slopebasin Up to 23 km

Van Konijnenburg et al1999 Morsilli et al 2000Eberli et al 2004

Maiella platform Italy Upper CretaceousCenomanian toMasstrichtian

1100 35 Toe of slopebasin 3ndash15 km 100ndash200 m Yes (dimensionunknown)

Bornhold and Pilkey 1971Crevello and Schlager1980 Eberli and Ginsburg 1989Mullins et al 1984

Bahamas Modern 700ndash1200 m 30ndash70 Upper slope tobasin

Up to 55 km 100ndash2000 m 10ndash40 km(W and L)

Jansonetal

139

seismic slice is more consistent with a deep-watergravity-flow-deposit interpretation than an isolatedshallow-water carbonate-platform interpretation

Core observation also (Enos 1977 Loucks et alin press) strongly favors a deep-water sediment-gravity-flow origin The Tamabra consists of fourtypes of breccias grainstones rare mud-rich wacke-stones and packstones and three key shalemudstoneintervals Shallow-water fauna as fragmental debrisis not an indicator of shallow-water deposition noris the presence of thick grainstone intervals Nu-merous well-documented studies such as from theJurassic of Italy (Bosellini et al 1981 Zempolichand Hardie 1997) the Permian of Texas (Kerans2001) and the HolocenendashPleistocene of the Baha-mas (Grammer et al 1993) have shown conclu-sively that thick reservoir-quality grainstones arecommonly shed from platform margins during eu-static highstandsOther excellent indicators of waterdepth are the fine-grained shalemudstone unitsthat blanket Poza Rica field at several intervals(Figure 4) These are characterized by deep-watermicrofauna such as globigerinid foraminifers

Stratigraphic Architecture of Toe-of-Slope ApronDespite the recent discussion by Horbury et al(2004) previously mentioned the Poza Rica oil fieldin the Tamabra Formation along the Golden Laneplatform remains commonly used as a classic exam-ple of a carbonate debris toe-of-slope apron (Mullinsand Cook 1986) The debris apron was depositednext to amostly aggrading carbonate platformwithan escarpment thatwas asmuch as 1200m (3937 ft)high This architecture is similar to that of othersteep carbonate escarpments such as the UpperCretaceous Maiella platform margin (Eberli et al1993 Van Konijnenburg et al 1999) the UpperCretaceous Apulia platform in Italy (Bosellini et al1999 Borgomano 2000 Bosellini 2001 BraccoGartner et al 2002) the Lower Cretaceous Bar-remian platform around the Vocontian Basin inFrance (Hunt and Tucker 1993 Savary and Ferry2004) the Cambrian and Silurian carbonate plat-form inGreenland (Surlyk and Ineson 1987 1992Ineson and Surlyk 1995) and theUpperDevonianFrasnian platform in the Canadian Rocky Moun-tains (McLean andMountjoy 1993Mountjoy and


Becker 2000 Whalen et al 2000) The Poza Ricatoe-of-slope apron has a large amount of redepos-ited debris that extendedmore than 25 km (16mi)away from the platform margin This is relativelylarge compared with most other carbonate plat-forms (Table 3) The Poza RicandashGolden Laneapron shows between 400 m (1312 ft) of carbon-ate gravity-flow sediment accumulation at the toeof the Golden Lane platform and 150m (492 ft) atthe edge of our data 15 km (9 mi) away from theplatform Thick debris apron deposits are docu-mented for the Cambrian and Silurian of Green-land (sim200m [sim650 ft]) (Surlyk and Ineson 19871992 Ineson and Surlyk 1995) the CarboniferousViseanndashSerpukhovian platform of the Pre caspianBasin (sim200 m [650 ft]) (Collins et al 2006) andpossibly around the Upper Cretaceous Apuliaplatform (gt300 m [gt984 ft]) In the Tamabra For-mation debris-flow deposits extend into the basinfarther than 15 km (93 mi) A few published ex-amples document such an extent away from theplatform such as the Cambrian and Silurian ofGreenlandwhich extends asmuch as 70 km(43mi)away from the platform margin the Apulia plat-form which may extend as much as 23 km (14 mi)(Bosellini et al 1999 Borgomano 2000 Bosellini2001 Bracco Gartner et al 2002) and the isolatedbasin-floor fan that is associated with the LowerCretaceous Barremian Vercors and Vivarais plat-forms in the Vocontian Basin in southeasternFrance which extend up to 35 km (22 mi) awayfrom the margin (Hunt and Tucker 1993 Savaryand Ferry 2004)

Fan-shaped geometries identified in the seismicdata have lateral dimensions between 2 and 5 km(12 and 31 mi) and similar longitudinal dimen-sions in the flow-parallel direction If these seismicfeatures represent a basin-floor fan they are thensmaller than the well-documented Lower Creta-ceous Barremian basin-floor fan in the southeast ofFrance (Savary and Ferry 2004) or the lobes iden-tified at the toe of slope in the Columbus Basin intheBahamas (Bornhold andPilkey 1971) althoughslightly bigger than the Permian toe-of-slope fan inthe Permian Basin in west Texas (Mazzullo 1994Montgomery 1996 Pacht et al 1996 MazzulloandMontgomery 1997 Playton and Kerans 2002

exico

Mazingue-Desailly 2004 Janson et al 2007)Thisfan would fall into the category of the small-sizecalcitic submarine fan of Payros and Pujalte (2008)Basin-floor fans are thought to have been createdby focused basinward export of platform-top andupper-slope deposits Sediment export from the plat-form top to the basinal area is focused through ex-isting channel on the slope amechanism commonlyobserved in carbonate slope (Mullins et al 1984Playton andKerans 2002) In the SantaAgueda dataset numerous small channels can be observed Theirdimensions are comparable to or slightly smallerthan those of typical channels observed in siliciclasticdeep-water systems (Clark and Pickering 1996) andin carbonates (Table 3) (Mullins et al 1984 Garcia-Mondejar andFernandezMendiola 1993Anselmettiet al 2000 Eberli et al 2004 Savary and Ferry2004)

Implications for Hydrocarbon Exploration and ProductionEvidence throughout the geologic record showsthat grainy porous sediments can accumulate onthe slope of carbonate platforms and in the basinas the result of gravity-flow deposits Only a fewexisting reservoirs are producing from carbonate-slope and basin deposits The Poza Rica field re-mains the most widely cited example (Guzman1967 Enos 1985) The other known deep-watercarbonate-producing reservoirs are from the Permianof west Texas (Mazzullo and Reid 1987 Mazzullo1989) Numerous small fields produce them fromcarbonate-redeposited sediment shed from surround-ing shelves into the Midland and Delaware basinsA volumetrically significant part of Tengiz fieldof Kazakhstan production comes from the slope(Weber et al 2003 Collins et al 2006) Howeverit is not really a genuine slope or basin reservoir be-cause the entire oil column extends from the plat-form top to the upper slope

The Poza Rica field is commonly seen as theresult of a pure stratigraphic trap created by lateralpinch-out of porous toe-of-slope apron deposits totight pelagic deposits (Guzman 1967) This studyshows that it is in fact a stratigraphic trap combinedwith a structural trap because of basement blockuplift Inwest Texas fields producing from the slope

and basin formation are typically found in strati-graphic traps or a combination trap

In the absence of a structural play the main re-quirement for a slope and basinal reservoir is isola-tion of these grainy porous deposits from the com-monly porous carbonate margin The toe-of-slopeapron has the potential to produce a margin parallelzone of porous rock that accumulates at the toe ofslope Unlike the slope apron model of Mullins andCook (1986) the toe-of-slope apron is detachedfrom the margin top and ideally could form a strat-igraphic trapThe toe-of-slope apron consists of amixbetween a continuous wedge of platform-derivedcoarse sediment along the platform margin and anamalgamation of channelized gravity flow that ac-cumulated at the toe of slope such as the one doc-umented for the Holocene of the Tongue of theOcean in the Bahamas This model of a toe-of-slopestratigraphic trap was proposed 20 yr ago (Mullinsand Cook 1986) but the only known producingexamples are Poza Rica field and the Zechstein Do-lomite in Poland where hydrocarbons are producedby detached accumulation of grainy rocks that aredeposited as a fanlike structure in a toe-of-slope apron(Barnetche and Illing 1956 Trela et al 2003) Theexisting field in west Texas developed in a channe-lized fan where accumulation of porous grainy rockoccurs in antecedent topography at the toe of slopeA true isolated basin-floor fan reservoir has not beendocumented yet except perhaps for the Wieclawslump or the Sulecin oil field in Poland which werecalled slumps byTrela et al (2003) but are describedas isolated accumulations of packstone and grain-stone at the toe-of-slope-to-basin transition

In the Poza Rica field the best reservoir-qualityrocks are found in grainy concentrated density flowsand debris flows with a grainy matrix Most of theporosity is primary porosity and burial dissolutionThe absence of significant terrestrial input has pre-vented extensive early burial precipitation (Louckset al in press)

In the Permian Basin deposits that are chargedwith hydrocarbon range from fractured tight ordolomitized debris flows in erosive channels to cleanoolithic sand in both toe-of-slope channel or basin-floor fan settings (Griffin and Breyer 1989 Salleret al 1989 Leary and Feeley 1991)

Janson et al 141

CONCLUSIONS

The integration of two 3-D seismic data sets allowsus to unravel the architecture of the Golden Laneplatform and its associated debris apron in the PozaRica field area The karstifiedGolden Lane platformtop and margin is bounded by a steep channelizedslope that grade into the toe-of-slope and basinalgravity-flow deposits The regional reconstructedarchitecture shows that the platform-to-basin reliefcould have been up to 1200 m (3937 ft) at the endof the Albian time The debris apron extends morethan 15 km (93 mi) away from the margin At theedge of our seismic data set 15 km (93 mi) awayfrom the margin the Tamabra Formation is stillmore than 100 m (328 ft) thick The gravity-flowdeposits that form the Tamabra Formation and thePoza Rica field consist of a complex stack ofdebris-flow deposits hyperconcentrated density-flow deposits and turbidites These Albian de-posits can be organized into four depositional se-quences The seismic reflection characters and thecore information consistently show that the lowertwo sequences are dominated by debris-flow de-posits whereas the upper two sequences have muchmore hyperconcentrated flow deposits that formlarge-scale lobate features up to 5 km (3mi) in sizeThis study confirms the deep-water origin of theTamabra Formation and shows the seismic ex-pression of this large debris apron associated withan aggrading Cretaceous carbonate platformThese debris aprons are common throughout thegeologic records and have the potential to hostsignificant volumes of hydrocarbon Besides PozaRica other existing basinal carbonate reservoirsinclude the Permian of west Texas and Poland andthe Carboniferous fields in the Caspian area

REFERENCES CITED

Anselmetti F G P Eberli and Z-D Ding 2000 From theGreat Bahama Bank into the straits of Florida A marginarchitecture controlled by sea level fluctuations and oceancurrents Bulletin of the Geological Society of Americav 112 p 829ndash844 doi1011300016-7606(2000)112lt829FTGBBIgt20CO2

Bahorich M S and S L Farmer 1995 3-D seismic discon-tinuity for faults and stratigraphic features The coher-


ence cube Society of Exploration Geophysicists 65thAnnual International Meeting Technical Program Ex-panded Abstracts v 14 p 93ndash96

Barnetche A and L V Illing 1956 The Tamabra Lime-stone of the Poza Rica oil field Veracruz Mexico20th International Geological Congress p 38

Bebout D G A H Coogan andCMMaggio 1969GoldenLanendashPoza Rica trends Mexico An alternate interpreta-tion AAPG Bulletin v 53 p 706

Bebout D G and R G Loucks 1977 Stuart City trend(Lower Cretaceous) south Texas A carbonate shelf mar-gin model for hydrocarbon exploration The University ofTexas at Austin Bureau of Economic Geology Report ofInvestigations no 78 80 p

Betzler C J J G Reijmer K Bernet G P Eberli and F SAnselmetti 1999 Sedimentary patterns and geometriesof the Bahamian outer carbonate ramp (MiocenendashlowerPliocene Great Bahama Bank) Sedimentology v 46p 1127ndash1144 doi101046j1365-3091199900268x

Borgomano J R F 2000 The Upper Cretaceous carbonatesof the GarganondashMurge region southern Italy A modelof platform-to-basin transition AAPG Bulletin v 84p 1561ndash1588

Bornhold B D and O H Pilkey 1971 Bioclastic turbiditesedimentation in Columbus Basin Bahamas GeologicalSociety of America Bulletin v 82 p 1341ndash1354 doi1011300016-7606(1971)82[1341BTSICB]20CO2

Bosellini A 1984 Progradation geometries of carbonateplatforms Examples from the Triassic of the Dolomitesnorthern Italy Sedimentology v 31 p 1ndash24

Bosellini A 2001 Scalloped vs faulted carbonate platformmargins and the origin of basinal megabreccias (abs)Geological Society of America Annual Meeting p 409

Bosellini ADMasetti andM Sarti 1981A Jurassic ldquoTongueof the Oceanrdquo infilled with oolitic sands The BellunoTrough Venetian Alps Italy Marine Geology v 44p 59ndash95 doi1010160025-3227(81)90113-4

Bosellini A C Neri and V Luciani 1993 Platform margincollapses and sequence stratigraphic organization of car-bonate slope CretaceousndashEoceneGargano Promontorysouthern Italy Terra Nova v 5 p 282ndash297

Bosellini A M Morsilli and C Neri 1999 Long-termevent stratigraphy of the Apulia platformmargin (UpperJurassic to Eocene Gargano southern Italy) Journal ofSedimentary Research v 69 p 1241ndash1252

BraccoGartnerGLMMorsilliW Schlager andABosellini2002 Toe-of-slope of a Cretaceous carbonate platform inoutcrop seismicmodel and offshore seismic data (ApuliaItaly) International Journal of Earth Sciences v 91p 315ndash330 doi101007s005310100213

Brown Jr L F and W L Fisher 1980 Principles of seismicstratigraphic interpretation interpretation of depositionalsystems and lithofacies from seismic data in L F BrownJr and W L Fisher eds Seismic stratigraphy interpreta-tion and petroleum exploration AAPG Continuing Edu-cation Course Note Series v 16 p 1ndash125

Brown A A and R G Loucks 1993 Influence of sedimenttype and depositional processes on stratal patterns in thePermian basin-margin Lamar Limestone McKittrick Can-yon Texas in R G Loucks and R Sarg eds Carbonate

exico

sequence stratigraphy Recent advances and applicationsAAPG Memoir 57 p 133ndash156

Chen J C Acosta Aduna F Sanchez Lu J Patino and MOlivella 2001 Petrophysical characteristics depositionalsystems and model of geological evolution in the GoldenLane carbonate sequences Gulf Coast Association ofGeological Societies Transactions v 51 p 31ndash44

Chen Q and S Sydney 1997 Seismic attributes technol-ogy for reservoir forecasting and monitoring The Lead-ing Edge v 16 p 445ndash456 doi10119011437657

Clark J D and K T Pickering 1996 Architectural elementsand growth patterns of submarine channels Applica-tion to hydrocarbon exploration AAPG Bulletin v 80p 194ndash221

Clark J D N H Kenyon and K T Pickering 1992 Quanti-tative analysis of the geometry of submarine channels Im-plications for the classification of submarine fans Geol-ogy v 20 p 633ndash636 doi1011300091-7613(1992)020lt0633QAOTGOgt23CO2

Collins J F J A M Kenter P M Harris G KuanyshevaD J Fischer and K L Steffen 2006 Facies and reservoir-quality variations in the late Visean to Bashkirian outerplatform rim and flank of the Tengiz buildup Precas-pian Basin Kazakhstan in P M Harris and L J Webereds Giant hydrocarbon reservoirs of the world Fromrocks to reservoir characterization and modeling AAPGMemoir 88 p 55ndash95

Coogan A H D G Bebout and C Maggio 1972 Deposi-tional environments and geologic history of Golden Laneand Poza Rica trend Mexico An alternative view AAPGBulletin v 56 p 1419ndash1447

Cook H E P N McDaniel E W Mountjoy and L CPray 1972 Allochthonous carbonate debris flows at De-vonian bank (ldquoreef rdquo) margins Alberta Canada Bulletinof Canadian Petroleum Geology v 20 p 439ndash486

Crevello P D andW Schlager 1980 Carbonate debris sheetsand turbidites Exuma Sound Bahamas Journal of Sedi-mentary Petrology v 50 p 1121ndash1147

Eberli G P and R N Ginsburg 1989 Cenozoic prograda-tion of northwestern Great Bahama Banks a record oflateral platform growth and sea-level in P D CrevelloJ J Wilson J F Sarg and J F Read eds Controls oncarbonate platform and basin development SEPM Spe-cial Publication 44 p 339ndash351

Eberli G P D Bernoulli D Sanders and A Vecsei 1993From aggradation to progradation The Maiella platformAbruzzi Italy in J A T Simo R W Scott and J-PMasse eds Cretaceous carbonate platforms AAPGMemoir 56 p 213ndash232

EberliG P F SAnselmettiCBetzler J-H vanKonijnenburgandD Bernoulli 2004 Carbonate platform to basin tran-sitions on seismic data and in outcrops Great BahamaBank and theMaiella platformmargin Italy inG P EberliJ L Masaferro and J F R Sarg eds Seismic imagingof carbonate reservoirs and systems AAPGMemoir 81p 207ndash250

Enos P 1977 Tamabra Limestone of the Poza Rica trendCretaceousMexico Society of Economic Paleontologistsand Mineralogists Special Publication 25 p 273ndash314

Enos P 1985 Cretaceous debris reservoirs Poza Rica field

Veracruz Mexico in P O Roehl and P W Choquetteeds Carbonate petroleum reservoirs Casebooks in earthscience New York Springer-Verlag p 455ndash469

Enos P and B P Stephens 1993 Mid-Cretaceous basinmargin carbonates east-central Mexico Sedimentol-ogy v 40 p 539ndash556 doi101111j1365-30911993tb01349x

Fernaacutendez-Mendiola A I Goacutemez-Peacuterez and J Garciacutea-Mondeacutejar 1993 AptianndashAlbian carbonate platformsCentral Basque-Cantabrian Basin Northern Spain AAPGBulletin v 56 p 315ndash324

Flood RD and J E Damuth 1987Quantitative character-istics of sinuous distributary channels on the Amazondeep-sea fan Geological Society of America Bulletinv 98 p 728ndash738 doi1011300016-7606(1987)98lt728QCOSDCgt20CO2

Fontaine J M R Cussey J Lacaze R Lanaud and LYapaudjian 1987 Seismic interpretation of carbonate de-positional environments AAPG Bulletin v 71 p 281ndash297

George A D P E Playford and C M Powell 1995 Plat-form margin collapse during Famennian reef evolutionCanning BasinWestern Australia Geology v 23 p 691ndash694

Galicia J G 2000 The offshore Golden Lane New outlineof opportunities from intergration of geologic and geo-physical data Gulf Coast Association of Geological So-cieties Transactions v 50 p 11ndash15

Garcia-Mondejar J and P A Fernandez-Mendiola 1993Sequence stratigraphy and systems tracts of a mixed car-bonate and siliciclastic platform-basin setting The Albianof Lunada and Soba northern Spain AAPG Bulletinv 77 p 245ndash275

Goldhammer R K 1999 Mesozoic sequence stratigraphyand paleogeographic evolution of northeast Mexico inC Bartolini J L Wilson and T F Lawton Mesozoicsedimentary and tectonic history of north-central MexicoGeological Society of America Special Paper 340 p 1ndash58

Gradstein F M F P Agterberg J G Ogg J Ardenbol PVan Veen J Thierry and Z Huang 1994 A Mesozoictime scale Journal of Geophysical Research v 99p 24051ndash24074

Grammer G M R N Ginsburg and P M Harris 1993Timing of deposition diagenesis and failure of steep car-bonate slopes in response to a high-amplitudehigh-frequency fluctuation in sea level Tongue of the OceanBahamas in R G Loucks and J F Sarg eds Carbonatesequence stratigraphy Recent developments and appli-cations AAPG Memoir 57 p 107ndash131

Griffin A F and J A Breyer 1989 New exploration targetsin northern Midland Basin Depositional and diagenetichistory of theWest Smyer field Hockley County Texasin J E Flis R C Price and J F Sarg eds Search for thesubtle trap Hydrocarbon exploration in mature basinsMidland Texas West Texas Geological Society v 89-85 p 75ndash96

Guzman E J 1967 Reef type stratigraphic traps in MexicoOrigin of oil geology and geophysics 7th World Petro-leum Congress p 461ndash470

Janson et al 143

Haq B U J Hardenbol and P R Vail 1987 Chronology offluctuating sea levels since the Triassic Science v 235p 1156ndash1167

Harris M T 1994 The foreslope and toe-of-slope faciesof the Middle Triassic Latemar build-up (Dolomitesnorthern Italy) Journal of Sedimentary Research v B64p 132ndash145

Horbury A H Hernandez A Marhx A Ojeda G Ita andJ Estrada 2004 Revitalizing the Poza Rica field Newinsights into the Tamabra reservoir and a tale of a para-digm lost AAPG International Conference httpwwwsearchanddiscoverynetdocumentsabstracts2004intl_cancunindexhtm (accessed August 2010)

Hunt D and M E Tucker 1993 The middle CretaceousUrgonian platform of southeastern France in J A TSimo R W Scott and J-P Masse eds Cretaceous car-bonate platforms AAPG Memoir 56 p 409ndash453

Ineson J and F Surlyk 1995 Carbonate slope aprons in theCambrian of North Greenland Geometry stratal pat-terns and facies in K T Pickering R N Hiscott N HKenyon F Ricci Lucchi and R D Smith eds Atlas ofdeep-water environments Architectural style in turbiditesystems London Chapman Hall p 56ndash62

Janson X 2002 Architecture and seismic expression of Mio-cene carbonate barrierndashlagoon systems Ermenek platformTurkey and Zhujiang platform South China Sea PhDthesis University of Miami Miami Florida 298 p

Janson X R Loucks C Kerans A Marhx and C Reyes2004 Karstification of the Lower Cretaceous Tuxpandetached platform Golden Lane Mexico (abs) AAPGAnnual Meeting Expanded Abstracts v 13 p 71

Janson X C Kerans J A Bellian and W Fitchen 2007Three-dimensional geological and synthetic seismicmodel of Early Permian redeposited basinal carbonatedeposits Victorio Canyon west Texas AAPG Bulletinv 91 p 1405ndash1436 doi10130605210705188

Kerans C 2001 Stratigraphy and reservoir facies develop-ment Slope-basin carbonate andmixed clasticndashCarbonatesystems Reservoir Characterization Research LaboratoryAnnual Field Trip Guidebook Bureau of Economic Ge-ology University of Texas at Austin Austin Texas p 22

Kerans C 2002 Styles of rudist buildup development alongthe northern margin of the Maverick Basin Pecos RiverCanyon southwest Texas in S P Dutton S C Ruppeland T F Hentz eds Gulf Coast Association of Geolog-ical Societies Transactions SEPM Gulf Coast Associa-tion of Geological Societies and Gulf Coast Section v 52p 501ndash516

Kerans K and R G Loucks 2002 Stratigraphic setting andcontrols on occurrence of high-energy carbonate beachdeposits Lower Cretaceous of the Gulf of MexicoTransactions of the Gulf Coast Association of GeologicalSocieties v 52 p 517ndash526

Lawson E C 1989 Subaqueous gravity flow and associateddeposits in the Rader Member Capitan reef complex(Permian) Delaware Mountains west Texas Masterrsquosthesis University of Wisconsin-Madison Madison Wis-consin 160 p

Leary D A andM H Feeley 1991 Seismic expression andsedimentologic characteristics of a Permian (Wolfcampian)


carbonate submarine fan Midland Basin west Texas in PWeimer and M H Link eds Seismic facies and sedimen-tary processes of submarine fans and turbidite systemsNew York Springer-Verlag p 303ndash315

Lehmann C D AOsleger and IMontantildeez 1998 Controlson cyclostratigraphy of Lower Cretaceous carbonatesand evaporites Cupido and Coahuila platforms north-eastern Mexico Journal of Sedimentary Research Stra-tigraphy and Global Studies v 68 p 1109ndash1130

Lomando A J P J Chimney and J Popek 1995 Trap andseal analysis in carbonate shelf margin stratigraphic trapexploration Example from the lowerMiocene ZhujiangFm Pearl River Mouth Basin Peoplersquos Republic of China(abs) AAPG1996 International Convention and Exposi-tion Meeting Nice France p 26

Loucks R C Kerans X Janson M A Marhx in pressLithofacies analysis and stratigraphic architecture of adeep-water carbonate debris apronLowerCretaceous (Al-bian) Tamabra Formation Poza Rica field area Mexi-co in C Shipp P Weimer and H Posamentier edsMass-transport deposits in deepwater settings SEPMSpecial Publication 95

Macurda D B 1997 Carbonate seismic facies analysis inI Palaz and K J Marfurt eds Carbonate seismologyGeophysical development series Tulsa Oklahoma So-ciety of Exploration Geophysicists v 6 p 95ndash119

Massaferro J L R Bourne and J C Jauffred 2004 Three-dimensional seismic volume visualization of carbonatereservoirs and structures inG P Eberli J L Masaferroand J F Sarg eds Seismic imaging of carbonate reser-voirs and systems AAPG Memoir 81 p 11ndash41

Mazingue-Desailly V P G 2004 Assessing the influence ofdiagenesis on reservoir quality Happy Spraberry fieldGarza County Texas Masterrsquos thesis Texas AampM Uni-versity College Station Texas 69 p

Mazzullo S J 1989 Subtle traps in Ordovician to Permiancarbonate petroleum reservoirs Permian Basin An over-view in J E Flis R C Price and J F Sarg eds Searchfor the subtle trap Hydrocarbon exploration in maturebasins West Texas Geological Society Midland TexasWest Texas Geological Society v 89ndash85 p 155ndash180

Mazzullo S J 1994 Dolomitization of periplatform carbon-ates (Lower Permian Leonardian)Midland Basin TexasCarbonates and Evaporites v 9 p 95ndash112 doi101007BF03175189

Mazzullo S J and S L Montgomery 1997 Permian ldquoWolf-camprdquo limestone reservoirs Powell Ranch field easternMidland Basin Discussion and reply AAPG Bulletinv 81 p 1750ndash1755

Mazzullo S J and A M Reid 1987 Basinal Lower Permianfacies PermianBasin Part II Depositional setting and res-ervoir facies of Wolfcampian Lower Leonardian basinalcarbonates West Texas Geological Society Bulletinv 26 p 5ndash10

McFarlan E and L S Menes 1991 Lower Cretaceous inthe Gulf of Mexico Basin in A Salvador ed The geol-ogy of North America Boulder Colorado GeologicalSociety of America v J p 181ndash204

McLean D J and E W Mountjoy 1993 Upper Devonianbuildup-margin and slope development in the southern

exico

Canadian Rocky Mountains Geological Society of Amer-ica Bulletin v 105 p 1263ndash1283 doi1011300016-7606(1993)105lt1263UDBMASgt23CO2

Mitchum R M J P R Vail and J B Sangree 1977 Seis-mic stratigraphy and global changes of sea level Part 6Stratigraphic interpretation of seismic reflection patternsin depositional sequences Section 2 Application of seis-mic reflection configuration to stratigraphic interpretationin C E Payton ed Seismic stratigraphy Applicationsto hydrocarbon exploration AAPG Memoir 26 p 117ndash133

Montgomery S L 1996 Permian ldquoWolfcamprdquo limestonereservoirs Powell Ranch field eastern Midland BasinAAPG Bulletin v 80 p 1349ndash1365

Morsilli M G Rusciadelli and A Bosellini 2002 Large-scale gravity-driven structures Control on margin archi-tecture and related deposits of a Creataceous carbonateplatform (Montagna della Maiella Central ApenninesItaly) in M Rinaldo Barchi S Cirilli and G Minellieds Geological and geodynamic evolution of the Apen-nines Societa Geologica Italiana Volume Speciale v 1Part II Rome Italy Societa Geologica Italiana p 619ndash628

Mountjoy EW and S Becker 2000 Frasnian to Famenniansea level changes and the Sassenach Formation JasperBasin Alberta Rocky Mountains in P W Homewoodand G P Eberli eds Genetic stratigraphy on the ex-ploration and production scales Case studies from thePennsylvanian of the Paradox Basin and the Upper De-vonian of Alberta Bulletin des Centres de RecherchesElf Exploration Production Memoir 24 Pau Elf E PEditions p 181ndash201

Mulder T and J Alexander 2001 The physical character ofsubaqueous sedimentary density flows and their depos-its Sedimentology v 48 p 269ndash299 doi101046j1365-3091200100360x

Mullins H T and H E Cook 1986 Carbonate apron mod-els Alternatives to the submarine fan model for paleoen-vironmental analysis and hydrocarbon exploration Sedi-mentaryGeology v 48 p 37ndash79 doi1010160037-0738(86)90080-1

Mullins H T K C Heath H M Van Buren and C RNewton 1984 Anatomy of a modern open-ocean car-bonate slope Northern Little Bahama Bank Sedimen-tology v 31 p 141ndash168 doi101111j1365-30911984tb01956x

Mullins H T A F Gardulski and A C Hine 1986 Cata-strophic collapse of the west Florida carbonate platformmargin Geology v 14 p 167ndash170 doi1011300091-7613(1986)14lt167CCOTWFgt20CO2

Pacht J A L Brooks and F Messa 1996 Stratigraphicanalysis of 3-D and 2-D seismic data to delineate porouscarbonate debris flows Northwestern Midland Basinwest Texas AAPG Bulletin v 80 p 1320ndash1321

Payros A and V Pujalte 2008 Calciclastic submarine fansAn integrated overview Earth-Science Reviews v 86p 203ndash246

Phelps R and C Kerans 2007 Architectural characteriza-tion and three-dimensional modeling of a carbonatechannel-levee complex Permian San Andres Formation

Last Chance Canyon New Mexico USA Journal ofSedimentary Research v 77 p 939ndash964 doi102110jsr2007085

Playford P E 1980 Devonian great barrier reef of CanningBasin western Australia AAPG Bulletin v 64 p 814ndash840

Playford P E N F Hurley C Kerans andM F Middleton1989 Reefal platform development Devonian of theCanning Basin western Australia in P D Crevello J IWilson J F Sarg and J F Read eds Controls on car-bonate platform and basin development SEPM SpecialPublication 44 p 187ndash202

Playton T E 2008 Characterization variations and con-trols of reef-rimmed carbonate foreslopes PhD thesisUniversity of Texas at Austin Austin Texas 302 p

Playton T E and C Kerans 2002 Slope and toe-of-slopedeposits shed from a late Wolfcampian tectonically activecarbonate rampmargin in S P Dutton S C Ruppel andT F Hentz eds Gulf Coast Association of GeologicalSocieties Transactions SEPM Gulf Coast Association ofGeological Societies and Gulf Coast Section v 52 p 811ndash820

Playton T E X Janson and C Kerans 2010 Carbonateslopes in N P James and R W Dalrymple eds Faciesmodel Geological Association of Canada St JohnsNewfoundland p 447ndash474

Robertson J D and H H Nogami 1984 Complex seismictrace analysis of thin beds Geophysics v 49 p 344ndash352 doi10119011441670

Rigby J K 1958 Mass movements in Permian rocks ofTrans-Pecos Texas Journal of Sedimentary Researchv 28 p 298ndash315

Rockwell D W and A Garcia Rojas 1953 Coordination ofseismic and geologic data in Poza RicandashGolden Lanearea Mexico AAPG Bulletin v 37 p 2551ndash2565

Salas G P 1949 Geology and development of Poza Rica oilfield Veracruz Mexico AAPG Bulletin v 33 p 1385ndash1409

Saller A H J W Barton and R E Barton 1989 Slopesedimentation associated with a vertically building shelfBone Spring Formation Mescalero Escarpe field south-eastern NewMexico in P D Crevello J L Wilson J FSarg and J F Read eds Controls on carbonate platformand basin development SEPM Special Publication 44p 275ndash288

Savary B and S Ferry 2004 Geometry and petrophysical pa-rameters of a calcarenitic turbidite lobe (Barremian-AptianPas-de-la-Cluse France) Sedimentary Geology v 168p 281ndash304 doi101016jsedgeo200404004

Soegaard K H Ye N Halik A T Daniels J Arney and SGarrick 2003 Stratigraphic evolution of latest Creta-ceous to early Tertiary Difunta foreland basin in north-east Mexico Influence of salt withdrawal on tectonicallyinduced subsidence by the Sierra Madre Oriental foldand thrust belt in C Bartolini R T Buffler and J FBlickwede eds The circum-Gulf of Mexico and theCaribbean Hydrocarbon habitats basin formation andplate tectonics AAPG Memoir 79 p 364ndash394

Srivastava P C W Stearn and E W Mountjoy 1972 ADevonian megabreccia at the margin of the ancient wall

Janson et al 145

carbonate complex Alberta Bulletin of Canadian Petro-leum Geology v 20 p 412ndash438

Surlyk F and J R Ineson 1987 Aspects of Franklinianshelf slope and trough evolution and stratigraphy inNorth Greenland Groslashnlands Geologiske UndersoslashgelseRapport v 133 p 41ndash58

Surlyk F and J R Ineson 1992 Carbonate gravity flow de-position along a platform margin scarp (Silurian NorthGreenland) Journal of Sedimentary Petrology v 62p 400ndash410

Taner M T 2001 Seismic attribute Canadian Society ofExploration Geophysicists Recorder v 26 p 48ndash56

Taner M T J S Schuelke R OrsquoDoherty and E Baysal1994 Seismic attributes revisited Society of ExplorationGeophysicists Annual Meeting Expanded TechnicalProgram Abstracts with Biographies p 1104ndash1106

TrelaMW Gorska and L Pikulski 2003 Prolific hydrocar-bon traps in the main dolomite porous carbonate slumpsin Zechstein Basin EAGE 65th Conference amp ExhibitionGeoscience and Its Role in Society Program with Ab-stract Stavanger Norway 2ndash 5 June 2003

Van Konijnenburg J H D Bernoulli and M Mutti 1999Stratigraphic architecture of a Lower CretaceousndashlowerTertiary carbonate base-of-slope succession Gran SassodrsquoItalia (central Appenines Italy) in P M Harris A HSaller and T Simo eds Advances in carbonate sequencestratigraphyApplication to reservoirs outcrops andmod-els SEPM Special Publication 63 p 291ndash315

Viniegra F and C Castillo-Tejero 1970 Golden LanefieldsVeracruzMexico inM THalbouty ed Geologyof giant petroleum fields AAPG Memoir 14 p 309ndash325

Waltham D 2008 Slope control on submarine channelwidths Journal of Sedimentary Research v 78 p 317ndash322 doi102110jsr2008036

Weber L J B P Francis P M Harris and M Clark 2003


Stratigraphy lithofacies and reservoir distribution Tengizfield Kazakhstan in W M Ahr P M Harris W AMorgan and I D Somerville eds PermondashCarboniferouscarbonate platforms and reefs SEPM Special Publica-tion 78 p 351ndash394

Whalen M T G P Eberli F S P Van Buchem and EMountjoy 2000 Facies models and architecture of uppercarbonate platforms RockyMountains Alberta Canadain P W Homewood and G P Eberli eds Genetic stra-tigraphy on the exploration and production scales Bulle-tin Des Centre De Recherches Exploration-ProductionMemoir Pau France Elf E P Editions v 24 p 139ndash175

Wilson J L 1990 Basement structural controls on Meso-zoic carbonate facies in northeastern Mexico A reviewInternational Association of Sedimentologists SpecialPublication 9 p 235ndash255

Wilson J L and W C Ward 1993 Early Cretaceous car-bonate platforms of northeastern and east-central Mex-ico AAPG Memoir 56 p 35ndash49

Wood L J and K LMize-Spansky 2009Quantitative seis-mic geomorphology of a Quaternary leveed-channel sys-tem offshore eastern Trinidad and Tobago northeasternSouth America AAPG Bulletin v 93 p 101ndash125 doi10130608140807094

Yurewickz D A T B Marler K A Meyerholtz and F XSiroky 1993 Early Cretaceous carbonate platform northrim of the Gulf of Mexico Mississippi and Louisiana inJ A T Simo R W Scott and J P Masse eds Creta-ceous carbonate platforms AAPGMemoir 56 p 81ndash96

Zempolich W G and L A Hardie 1997 Geometry of do-lomite bodies within deep-water resedimented oolite ofthe Middle Jurassic Vajont Limestone Venetian AlpsItaly Analogs for hydrocarbon reservoirs created throughburial dolomitization in J A Kupecz J G Gluyas andS Bloch eds Reservoir quality prediction in sandstonesand carbonates AAPG Memoir 69 p 127ndash162

exico

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January

Award from AAPG for best article in the AAPGBulletin in 1994 (first author) and in 2005(second author)

Robert Loucks Bureau of Economic Ge-ology University of Texas at Austin UniversityStation Box X Austin Texas 78713-8924

Robert G Loucks is a senior research scientist atthe Bureau of Economic Geology He receivedhis BA degree from the State University of NewYork at Binghamton in 1967 and his PhD fromthe University of Texas at Austin in 1976 Hisgeneral research interests include carbonateand siliciclastic sequence stratigraphy depo-sitional systems diagenesis and reservoircharacterization

M Alfredo Marhx Pemex Exploracion yProduccion Poza Rica Mexico

Alfredo Marhx-Rojano received his MI degreefrom the National University of Mexico (UNAM)in 2010 where he studied energetic subsurfaceresources he received his bachelorrsquos from Na-tional Polytechnic Institute in 1981 with anemphasis on surface geological studies fromSanta Catarina SLP Mexico He joined PetroacuteleosMexicanos (PEMEX) in 1983 His professionaldevelopment includes surface and subsurfacegeology sedimentology and stratigraphicstudies and reservoir development studies

Carlos Reyes Pemex Exploracion y Pro-duccion Poza Rica Mexico

Carlos A Reyes Loacutepez studied his MI degreefrom the National University of Mexico (UNAM)between 1986 and 1989 where he was a stu-dent of physics of reservoirs received his bach-elors from UNAM in 1982 with the ldquoAir andFoam Drillingrdquo He joined Petroacuteleos Mexicanos(PEMEX) in 1983 His professional developmentincludes surface and subsurface reservoir en-gineering studies and he has been team leaderseveral times in onshore and offshore projects

Francisco Murguia Pemex Exploracion yProduccion Poza Rica Mexico

Francisco Murguia is a seismic interpreter and iscurrently in charge of the representation of infor-mation technologies in the Poza RicandashAltamiraAsset of PEMEX Exploration and Production Heis certified in Landmark interactive interpretationsystems with great experience in the use of In-ternet and intranet technologies for access ofdata in the database and the application for the

106 Seismic Architecture Santa Agueda and Po

and turbidites in theupper twoAlbian sequences (Albian 3 andAlbian 4) Seismic data used in this study combined with coreobservations do not support the interpretation of the AlbianTamabra Formation being of shallow-water origin Seismic fea-tures identified as basin-floor fan channel and debris-flow de-posits have a shape and size that are similar to those of otherredeposited basinal carbonate deposits elsewhere The seismicarchitecture shows that the Poza Rica field is a typical exampleof thick accumulation of grainy porous carbonate deposits in abasinal setting This example shows the potential of a large hy-drocarbon accumulation in a tectonically modified stratigraphictrap around shallow-water carbonate platforms

INTRODUCTION

The eastern Golden Lane platform in Central Mexico and itsassociated thick basinal debris apron have been identified sinceits early oil discovery in the 1930s (Barnetche and Illing 1956Viniegra and Castillo-Tejero 1970 Coogan et al 1972 Enos1977Wilson 1990 McFarlan andMenes 1991 Goldhammer1999) Poza Rica field which produces from theAlbian TamabraFormation (Salas 1949) is considered a classic example of athick accumulation of redeposited carbonate sediment adja-cent to a high-relief shallow-water carbonate platform Becauseof the Poza Rica oil field three-dimensional (3-D) and 2-D seis-mic well logs and core are available for detailed study of thearchitecture of the linked platform slope and basinal deposi-tional environment Because little oil or gas production is presentoutside theAlbian ofMexico or the Permian of west Texas fromredeposited deep-water carbonate deposits they have receivedlesser attention than their siliciclastic counterparts

Combining 3-D seismic data over the Golden Lane plat-form and time-equivalent basinal deposits of Poza Rica field aswell as integrating well and core data has allowed us to analyzethe seismic architecture of a shallow-water carbonate-platformtop the platformmargin and the associated steep bypass slopealong with the time-equivalent toe-of-slope basinal apron ofredeposited carbonate The 3-D seismic data reveal not onlythe stratigraphic architecture of various redeposited sedimen-tary bodies but also their relative positions along the deposi-tional profile their dimensions and their morphology

Following a brief regional geologic introduction as well asa short description of the data and methods used in this studythis article discusses first the seismic architecture of a platformslope and basin observed in a composite regional seismic profile

za Rica Fields Mexico


ACKNOWLEDGEMENTS




REGIONAL SETTING



Janson et al 107




Jansonetal

109
















110Seism

icArchitectureSanta

Aguedaand

PozaRica

FieldsMexico

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among


depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy


intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm


The


bywisp

ytocontorted

beddingandthey


ofterrigenousmud

matrixG

rain

typesinclu


lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy


intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto



ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto


composedmainlyof

clayandsomevery



nesrepresenta

cessationof



was

shut

down

ontheadjacent

platform

allowingthem


eing

dilutedby

carbonatedebris





Janson et al 111








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











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Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











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Janson et al 135













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Janson et al 137



Results


Discussion




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Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















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HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January


ACKNOWLEDGEMENTS




REGIONAL SETTING



Janson et al 107




Jansonetal

109
















110Seism

icArchitectureSanta

Aguedaand

PozaRica

FieldsMexico

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among


depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy


intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm


The


bywisp

ytocontorted

beddingandthey


ofterrigenousmud

matrixG

rain

typesinclu


lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy


intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto



ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto


composedmainlyof

clayandsomevery



nesrepresenta

cessationof



was

shut

down

ontheadjacent

platform

allowingthem


eing

dilutedby

carbonatedebris





Janson et al 111








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January




Jansonetal

109
















110Seism

icArchitectureSanta

Aguedaand

PozaRica

FieldsMexico

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among


depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy


intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm


The


bywisp

ytocontorted

beddingandthey


ofterrigenousmud

matrixG

rain

typesinclu


lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy


intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto



ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto


composedmainlyof

clayandsomevery



nesrepresenta

cessationof



was

shut

down

ontheadjacent

platform

allowingthem


eing

dilutedby

carbonatedebris





Janson et al 111








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January
















110Seism

icArchitectureSanta

Aguedaand

PozaRica

FieldsMexico

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among


depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy


intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm


The


bywisp

ytocontorted

beddingandthey


ofterrigenousmud

matrixG

rain

typesinclu


lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy


intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto



ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto


composedmainlyof

clayandsomevery



nesrepresenta

cessationof



was

shut

down

ontheadjacent

platform

allowingthem


eing

dilutedby

carbonatedebris





Janson et al 111








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January

Limemudsto

newackesto

neSuspensio

ndepositsof

limeskeletalmud

asmuchas

5m

(15ft)

thickinterbedded

among


depositsof

theTamabra

Form

ation(Figures

56)indicateperiods

ofdominationby

lower

energy


intervalsof

thesedepositsare

also

themainrock

typesof

theAgua

NuevaFm

above

andtheTamaulipas

SuperiorFm


The


bywisp

ytocontorted

beddingandthey


ofterrigenousmud

matrixG

rain

typesinclu


lesradiolariansand

echinoidand

mollusk

fragm

ents

Mosto

fthe

limemudsto

nesarelow-energy


intervalsof

limemudsto

newackesto

nemay

befine-grainedplum

eassociated

with

gravity-flow

deposition

Terrigenousmudsto



ithintheTamabra

Form

ationThetexture

ranges

from

burrow

edterrigenousmudsto

nesto


composedmainlyof

clayandsomevery



nesrepresenta

cessationof



was

shut

down

ontheadjacent

platform

allowingthem


eing

dilutedby

carbonatedebris





Janson et al 111








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January








exico




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January




Janson et al 113







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















Jansonetal

139







exico








Janson et al 141

CONCLUSIONS


REFERENCES CITED



















exico




























Janson et al 143




























exico



























Janson et al 145



















exico

HOME

NEXT

PREVIOUS

START

CONTENTS

SEARCH

January







DATA AND METHODS

Data Used



exico



Janson et al 115







exico


Jansonetal

117

bl


Mapped Horizons








exico






Jansonetal

119









exico






Janson et al 121







exico





Janson et al 123



Janson et al 125











exico


Jansonetal

127



Janson et al 129








Isochore Map



Janson et al 131



Figure 20 Continued



Janson et al 133











exico


Janson et al 135













exico




Janson et al 137



Results


Discussion




exico


Authors LocationAge


ApproximateSlope

Height (m)

ApproximateSlope



Channels(width)











200 90 Basin 2 No






















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CONCLUSIONS


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CONCLUSIONS


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CONCLUSIONS


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January

bltn09107

Documents

hyperconcentrated density flows

poza rica fields

poza rica field

gray triangles pointing

maximum flooding surface

joined petrleos mexicanos

concentrated density flows

golden lane platform