PE

zohra KAlgeria,

Keywor

Recoveprior to knowledunconvetechnololow matresultedcarbonastimulatinducinghas achconceptthese reand geothis papsolution Tight saas havpermeamatrix cannot rates nnatural a largeproduce Increascombinetechnolointervenlow-per

ETROLEU

Kerboub azib phone: 00

rds: Uncon

erable reser1970. Com

dge of the pentional Pogies effecttrix permead in porosityate, and pytion to increg new oneshieved excet and justifyesources reomechanicsper is to o

ns. The Ordo

INTROD

and reservoving less

ability and porosity (Fbe produ

nor recovergas unless

e hydrauliced by a hori

ing demaed with newogies dening years, meability re

UM POTE

bi, Sr. Petro213 21549

nventional

rves in Algemplex and spetroleum saleozoic rtively. Thesbility. Pore y reductionritic cemenease the ms, typically tellent resultsy ongoing i

equires a thos to determoptimize theovician rese

DUCTION

oirs are genethan 0.

less than Fig.1). Succed at ecr economicthe well is

c fracture izontal wellb

and for nw drilling aneveloped

pushed deesources.

ENTIEL O

ophysicist , 301, fax: 00

Tight Sand

A

eria fields asubtle playssystem, highreservoirs e reservoirsmorpholog by predomts. Some re

matrix permethrough hyds that confirnvestigationorough und

mine the bese well formervoirs, loca

erally define1mD matten perce

ch reservoconomic floc volumes stimulated treatment bore.

natural gand completio

during thevelopment

OF TIGHT

SONATRA0 213 21 54

d Reservo

ABSTRACT

are mainly s were not h costs andwhich cous are compy is domina

minantly silieservoirs aeability by cdraulic fractrm the hydrn efforts in erstanding st drilling a

mation evalated in Illizi

ed rix

ent irs ow of by or

as, on he of

T(Eev

T SAND

ACH DCGA47180, zohr

ir, Illizi bas

T

from convepursued a

d risks. Impould be acclex and ofteated by the ca cementare naturallyconnecting turing. Recerocarbon int

this domaiof the geolo

and completuation, redbasin repre

hese reseE&P) stratevaluation te

IN ALGE

AST, Djenara.kerboub@

sin

entional rest that time ortant resoucessed byen difficult toextensive d

ation but aly fractured b

existing naent intense terest assocn. Successogy, stratigrtion methoduce uncert

esent our ca

rvoir typesegies and aechniques.

Fig.1 Cross-Pl

ERIA BAS

ane El Malik@sonatrach

servoirs, disbecause o

urces still rey using ado produce wdiagenesis lso with sombut require atural fractu

explorationciated with sful developraphy, petrods. The putainties andase study.

s require adequate fo

lot PHI/K

SIN

k Hydra h.dz

scovered of limited emain in dvanced with very that has me clay, artificial

ures and n activity this new

pment of ophysics rpose of d advice

specific ormation

I The Illizbroad inis bouMessaoTihemb

Fig. 2: Illi

It is shato a coperiod othe estMesozo

LLIZI BAS

zi basin wntra-cratoniunded by

oud ridge oka arch fa

zi Basin on the P

allow marinontinental of intense tablishment

oic sedimen

Fig.3: Illizi Basi

IN CASE S

which correic Paleozoiy the Ato the W

arther to the

East South flanPlatform

ne deposit lmargin suerosion that of a Patary column

in Stratigraphic

TUDY

sponds to c depressio

Amguid-Hasest and thEast Fig.2.

nk of the Sahara

located closbjected to at resulted aleozoic ann Fig.3.

column

a on ssi he .

an

se a in

nd

 

TcoinTtositoisseTafbyimofTthTrepe

W

TarotEoba ba TchGanacco Devofin Tavta

he Ordoonstitutes a

n Illizi basin,he Hamra

o coarse igmoidal cro massive ss interpretequence whe upper ffected by y several s

mmersion prf the Ouarghe Hamra

he best prohe flow rate

elation to ermeability

WELL FORU

hree Wells re considerthers to illuach well reqbjectives ancomprehen

ased on log

he Hamrharacterized

GR less thand low pccuracy in ontact.

Despite of tvaluation of an importa

n three wells

he petrophyvailable lo

able1.

ovician Ha major Hyd, objective oQuartzite isquartzitic sross beddinsandstone ted as ith a lower part of Hearly diagetage of dissrior to the mla sandstonQuartzite

olific reserve from this r

the fractuless than 1

MATION EVUNCERTAI

A, B and Cred in this pustrate Tighquires a carnd local consive well egs, cores an

ra Quartzd by a veran 15 °APIporosity ca

all poros

he poor ref logs suggant hydrocas Fig.4, 5 &

ysical resulgs are su

Hamra Qdrocarbon rof our studys made of sandstone ng grading rich in Skoa progra

r erosive boHamra Quaenesis matsolution sug

major floodinne. represents

voirs in Illizreservoir is ure intensmD.

VALUATIOINTIES

C within a sapaper amonht Sand resreful analysnditions to evaluation nd testing.

zite reservry low radioI, a high reausing a sity logs a

eservoir qugests the parbon beari 6

lts derived fummarized

Quartzite reservoir y.

medium rich in upward

olithos. It adational oundary.

artzite is erialized ggesting ng event

one of zi basin. in close

ity with

ON AND

ame field ng many servoirs. sis of the develop program

voir is oactivity, esistivity lack of nd fluid

ality the presence ng zone

from the in the

Fig.4 ELAN Well A

Floprasmin

ormation eogging androblematic.ssociated

measuremennterpretation

Well Availa

A Drilled 1979

GR/CANPH

B

Drilled 2009

GR/cal-Densit -No formpressurmeasur -No borimages

C

Drilled 2010

-GR /H- GR/LD- HNGS- GR/C- Sonic-BorehoimagesUBI/OB

Table.1

Fig.5 ELAN W

evaluation interpretaUncertainwith p

nts, signaln methods.

able Logs

ALI/ILD/DT

I/RHOB

Sed&Frchastud

iper/sonic ty

mation re rement

rehole s

-LaRoctest-1Dgeostud

DIL DT/CNL S

CBL/VDL scanner ole

s BMI

-1Dgeostud-Prointesonbore

1

Well B

with convation methonties are gphysics ol processi

Studies

dimentological racture aracterization dy.

boratory ck mechanical ts

D MEM omecanical dy

D MEM omecanical dy. ocessing and

erpretation of nic scanner & ehole images

ventional ods are generally of tool ng and

Results

pay interval =26Phie=5% , Sw=1Barefoot tested mwith gas & oiL sh Pay interval= 34Phie=4% , Sw=1DST-1: 212m3/h gas 0.54m3/h oil Flowed postfrac 2572 m3/h of ga7.23m3/h of oilBSW= 5-10% Pay interval=37mPhie=4.5% , Sw= Flowed during 6h40’after barefoDST-1 738m3/h of gas3.2 m3/h of oil 3of water on BSW10%

m 10% mud hows

4m 15%

test. as

m=25%

oot

350l/h

W=

EffectiveRw pardetermibecausedeflectiowater-bplot cawater sa The cedecreaswater sa The poto matrand clay Shale myield co Archie eporositie

To bepropertiin the e

ely, the forrameter is dned from Pe there is on. Often earing leven tend to aturation Sw

ementation sing porositaturation.

rosity deterrix changey presence.

models areorrect answe

equation bres.

Fig.6

etter defines and to r

estimation o

rmation wadifficult to ePS is not

no develothere is a

el for calibroverestim

w.

factor decy and leads

rmination ises, incompl.

e complex aers.

reaks down

ELAN Well C

ne the reduce the of hydrocar

ater resistivestimate. Reven reliabopment of bsence of ation. Pickeate Rw an

creases ws to lower th

s difficult dulete invasio

and may n

n at very lo

petrophysicuncertaintie

rbon in plac

vity Rw ble

a a

ett nd

ith he

ue on

not

ow

cal es ce

anexpa Sre-sahi-been-dipoun-boev-manstsh

Tthsulitinmde

Tmhoqu

nd fluid coxtensive laarameters i

ome advaneliable form

In low andstones igh requires Acceleratoetter signanvironmentMagnetic

irect measorosity wncertainty.Wellbore imoth depositivaluation stThe Sonic

measuremennd aids in etress distribhears wave

SEDIM

he sedimehe log to ubdivision thofacies ancluding a middle shore

eposit.

he Hamra qmarker Fig.

omogeneouuartz sand

Fig.7

ontact in tiaboratory as needed.

nced wireliation evalua

porosity the resistiv

s resistivity or neutron pal-to-noise al effects resonance

sure of ewith no

maging logional envirotudies. c Scanner nts of fast fevaluating

butions from anisotropy

ENTOLOG

ntological ccore calibrof the Ordand genetvariety of

eface and g

quartzite co7 and is

us facies dcemented t

Seismic sectio

ight reservanalysis for

ine loggingation as folland perm

vity contrastmodeling.

porosity logratio and

e logging oeffective an

matrix re

gs are esseonment and

tool offerformation vopen fractu

m both Stoney analysis.

GICAL STUD

core analysration leaddovician in tic paraseq

progradingglacio-fluvia

onstitutes a character

dominated bto quartzite.

n NE-SW/W-E

voirs, an r Archie

g allows low: meability t is very

s offer a smaller

offers a nd total esponse

ential for fracture

s better velocities ures and eley and

DY

ses and d to the

several quences g lower-al/marine

regional ized by by clean .

The coallowed

- QS

- w

The uppdominatsandstograins sorted a

The Ordseveral transforcomposmain sigaffect thpervasivand Illitquartz quartz o

The seqQuartzit

-Dissolu-Quartz-Growth-Dissolu-Growthpore-fillChlorite-Fractursedimencementa

ore descrip identifying

Quartzitic Sigmoidal cMassive with Skolitoper part of ted by

one rich inare mediu

and frequen

dovician resdiagenetic

rmation osition and thgnificant diahe petrophyve precipitate as wellat grain

overgrowths

quence of dte is as follo

ution of feldovergrowth

h of auution of h of pore-bing Illite;-I

e and ring occunt had beation and g

Fig.8 Th

ption of stwo distinc

Sandstcross beddi

Quartziticos bedding 

the Hamramassive

n Skolitos. um to finently cemente

servoirs wec events leof both he interstitiaagenetic altysical propeation of qu as the dcontacts fas Fig.8.

diagenesis ows:

dspar and ro; uthigenic

authigenibridging annsignificant

Kaolinter after

een lithifiedrain-contac

in section well A

several wet facies: 

one wng 

c Sandston

a Quartzite quartzi

The quar, moderateed by silica.

ere subjecteading to thmineralogical space. Theration whicerties are thartz cemen

dissolution avourable

in the Ham

ock fragmen feldspa

c feldspand pervasivt carbonat

e cementhe Ham

d by quarct dissolution

A

ells

ith

ne

is tic rtz ely .

to he cal he ch he nts of to

mra

nt; ar; ar; ve te, nt;

mra rtz n.

It octerepepo

DQdideisprasPupatsura

Perm

ability

(mD)

seems likccurred

emperatureseservoir ermeability orosity aver

Despite its pQuartzite wa

issolution evelopment

s some evidreservation ssociated orosity tenpper layersttribute of tubaerially eainfall condi

0,01

0,1

1

10

0

Perm

ability (mD)

kely that dto burieds up to degradationmainly less

raging 5%

Fig.9 Cross-Pl

poor reservoas subjected

event t of seconddence for th

of sewith fel

nds to be s of this rethis reservoexposed undtions.Fig.10

Fig.10 Thin sec

5 10

Porosit

diagenetic cd reserv

100°C n resultis than 1mD Fig.9.

lot PHI/K

oir quality thd to an earlyleading

dary porosithe developecondary ldspar dibetter tow

eservoir. A oir is that tder warm a0, 11.

ction well A

0 15

ty (%)

changes voir at

causing ng in and low

he Hamra y and late to the

ty. There ment and

porosity ssolution.

wards the common

they were and heavy

20

ELAS

TABA

ELA‐

BCA

S‐

A

1

Tight rfracturinexploratFrom frhigher N20°) aSW fauopened cement the prefracturehydroca

Two fadistinguThe fracementeor silica

The unumerosystem mainly maximuSE.

The peris extrefrom ldevelopsystem productthe cha20°, obopen orwith smreservoreservo

FRACTURCHARAC

reservoirs ng with a stion & produracture studfracture de

are observeults. Most and/or partFig.10. It h

esence of es seem arbon produ

amilies of uished: the acture maed or comp

a cement.

upper Haous stylolite

of low intenNS and N4

um horizont

rmeability omely low anlow to mpment of

this restive. Howevaracterizatiobserved in r partially ce

mall spacingir propertieir flow beha

RE NETWOCTERIZATI

are pronetrong impauction activdy of abouensity (N45ed in the pr

of these tially filled bhas been es

numerous to be

uction.

natural fraN°45 & N

y be opepletely cem

amra resees and a nnsity. These45° implyintal stress is

of the Hamnd the poromoderate.

open fracservoir wover, the inteon of the Ncores suggemented

g have a grs and they

aviour. Fig1

Fig.11

ORK ON

e to intensct on drillinities. t 122m cor5° & N10°roximity of N

fractures by silica or cstablished t

tensile Nsufficient

acture can N°10 fracturened, partimented by c

ervoir shoatural fracte fractures

ng that currs oriented N

mra rock maosity can ran

Without cture netwould be nerpretation aN45°, N10°gest that oN45° fractureat impact

will affect 1.

se ng,

res, ° to NE-are

clay that

N45° for

be res. ially clay

ows ture are

rent NW-

atrix nge the

work non and ° to only ures t on the

Minhycocothabpa

Awan

BstP

GEO

Most tight ren our case ydraulically ommercial gompletion ihe mechanibove, withinay intervals

F

A 1D mechworkflow wa

nd C. Fig.13

F

asic rock ptress fieldoisson’s rat

OMECANICA

servoirs arestudy (Figfracture tre

gas-flow ratt is necesscal propertin, and belo of Hamra q

Fig.12 Cross Se

hanical eas establish3

Fig.13 1D MEM

properties  sd, Young’stio, were de

AL STUDY

e thick, up g.12) that meated to protes. To optisary to undies of all th

ow the hydrquartzites.

ection E-W

arth model hed in both

WorkFlow

such as ths moduluetermined to

Y

to 200m must be oduce at mize the derstand he layers rocarbon

(MEM) wells B

e in-situ s, and o design

a fractuand wel

The shatheir hoin Hamstress im

The mrecommwell C excessitechnicafishing) to a con

This inOrdovicbasin evporoper

ure treatmell test data F

Fig.14

aly zones reomogeneity.mra quartzit

mbalance.

Fig.15 Rock

mechanical mended rais

to mitigateve back real constrainwere regis

nsiderable w

CON

ntegrated cian target iven thoughrm property

ent by usingFig.14 &15.

4 Stress Profil

emain stabl The breakes section

Properties Cali

earth msing the me breakout

eaming, sincnts (jammingstered in wewaste of tim

 

NCLUSIONS

study imps a promisi

h it has an ey.

g logs, core

e because kout observe

is due to

bration 

model studud weight ts and avoce numerog, break, anell B, leadin

me.

S

lies that ng play in

extremely p

res

of ed

a

dy in

oid us nd ng

the Illizi

poor

Tasremsiaswalpa

Tladisethprlacrpr

Gdececofr

ThiprrereBoiQ

Wbeaqdicosuanbatrun Inwgathen

he Hamra s a potentiaemarkable

medium-graiilica cemenspect. The

was subjelterations parameters.

he reservoiargely coniagenetic equence ihat partiallyrimary poro

ate dissolureating a ferecipitation

Generally thensity of faemented Nore, whilst actures are

he Hamra igh resisitivresence oeservoir is eservoir qua and C welil bearing

Quartzite.

Well C evearing intequifer preseifferent zonomprising uccessful and water fad candideatment  acncertainty.

n Well B thwas success

as and oil his reservonhanced pe

Quartzite wal reservoir thicknesned sandsttation givingupper part cted to presents t

r quality of ntrolled by

alteration. ncludes q

y and/or totosity but inution of tew vuggy pof clay cem

e Hamra Qulting and f45° fracture

mud loss conductive

Quartzite ivity related

of residualvery tight. ality, the evl logs sugge

in entire

valuated aerval with ence was tnes. Only

the entind a small lowed.  It wdate to ccording to

e hydraulicsful and imthirteen tim

oir is relaermeability.

which is conis characte

ss of cleantones with g to the rocof Hamra Q

many dthe best r

Hamra Quay fracturin

The diauartz overtally destronhibits comthe silica porosity andments.

Quartzite hafractures; oes are obsses suggese.

is characted probablyl oil and Despite h

valuation ofest the pres

zone of

as a hydrno indica

tested four the first w

ire intervaamount of

was considhydraulic o the fluid

c fracture trmproved themes. The flated to

nsidered erized by n fine to a strong

ck a tight Quartzite digenetic reservoir

artzite is ng and agenetic rgrowths oyed the mpaction,

cement d finally,

as a low pen and erved in st some

rized by y to the d/or the his poor f well A, sence of

Hamra

rocarbon ation of times in

well test al was f gas, oil dered as

fracture contact

reatment e flow of ow from fracture-

Well A drilled in 1979 has similar hydrocarbon potential to well B and C but just shows of gas and oil were observed in the well test. The well was abandoned definitively that time.   The well formation evaluation of tight sand remains complex and full of uncertainties that can be reduced by using appropriate parameters, interpretation methodology and logging tools.

Production of such reservoirs involves in several cases horizontal drilling and/or induced fracture program which is strongly dependant on correct characterization of the natural fracture systems and in situ stress conditions.

Considerable efforts are undertaken to develop and produce tight gas reservoirs in different basins of Algeria. An intensified program is conducted to optimize completion and fracture treatment at economic rates.

Table 2 presents the largest successful tight gas fields in Algeria where appropriate process has been implemented.

Field & location

Reservoir Formation type

Reservoir Properties

Phi% KmD

Applied Technology

Tiguentour S-W of Algeria

Lower Devonian

Sandstone 20 <1 - Underbalance drilling. -Horizontal drilling & Fracturing. -Multi hydraulic frac stages.

Krechba S-W of Algeria

Lower Devonian

Sandstone 8.5 <1 -Horizontal drilling. -Geosteering. -Multi hydraulic frac stages.

InSalah S-W of Algeria

Lower Devonian

Sandstone 10 -3D multi-azimuth seismic survey. -Nuclear Magnetic Resonance. -Directional drilling. - Hydraulic fracturing. -Improved proppant

Table.2

REFERENCES

1. Eschard R., Abdallah H., Braik F., Desaubliaux G. (2005) - The Lower Paleozoic succession in the Tassili outcrops, Algeria: Sedimentology and sequence stratigraphy. EAGE, First Break V. 23.

2. B. Kennedy (2011) Shale and Tight Gas Reservoirs Global Overview, Baker Hughes.

3. Stephen A. Holditch (2006), Tight Gas Sands, SPE, Texas.

4. Bikash K. Sinha, SPE, Badarinadh Vissapragada, SPE, Schlumberger; Lasse Renlie and Eiliv Skomedal, SPE, Statoil, Horizontal Stress Magnitude Estimation using the Three Shear Moduli – A Norwegian Sea Case Study, SPE 103079

5. J. YiMing (2010), Sonic Scanner in Geomechanics Applications, Schlumberger.

6. R. Paramatikul, New application of Sonic Scanner in Gas reservoir evaluation, Schlumberger

7. F. Sekour, K. Kartobi (2011) Geomecanical study of well C, Sonatrach.

8. A. Bensari, S. Grelaud, J. YiMing, 1D MEM Geomecanical study of well B, Schlumberger.

9. S.Bentaalla, S. Meriem, M. Terki (2010) End of well report: well C Sonatrach.

10. D. Bahmed (2010) End of well B report

11. Algeria Well Evaluation Conference (2007), Sonatrach-Schlumberger.

12. Algeria Tight Gas Book (2009), Halliburton.

13. Sedimentological Study of the Ordovician Reservoirs (2006), Sonatrach-Numhyd

14. Overview of Tight Gas Field Development in the Middle East and North Africa Region, SPE 126181.

15. A. Ali (2010), Tight Sand Formation Testing, Schlumberger.

16. George E. (2009), Fracturing Basics, King Engineering.

17. R. Lamali, K. Russell (2010), Sonic Scanner Field Data – Advisor Report well C, Schlumberger DCS.