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Using elemental chemostratigraphy forhigh-resolution correlation and improvedgeosteering in Mid-Continent gas shales
Mike DixHalliburton – Sperry Drilling Services
Oklahoma Gas Shales ConferenceOctober 22, 2008
Mineralogy
Lithology
Depositional Facies
DiageneticFacies
ReservoirQuality
Stratigraphy
Rare EarthElements
Elemental Applications for E&P
Wellbore Positioning: Critical picks for casing point, coring point, TD, and Chemosteering®
Reservoir Development: Improved correlation, delineation, fairway recognition, and model input
Frac Design (in development): Prediction of critical mechanical properties in gas shales
Formation Evaluation: Prediction of lithology, mineralogy, and potentially reservoir quality
Elemental Applications for E&P
Elemental Chemostratigraphy
A proven correlation technique that utilizes changes in the inorganic geochemical composition of siliciclastic and carbonate sediments.
- Fossils are sparse or absent- High sedimentation rates reduce biostratigraphic resolution- Petrophysical log signatures are ambiguous
Data for up to 50 elements are determined in the laboratory using ICP-OES/MS and XRF instruments, allowing the “fingerprinting” of sedimentary rock units.
Particularly useful where:
Highly successful for correlation on scales ranging from individual reservoirs within a field to thick sequences across a region.
Problem: Poor Field-Scale CorrelationCarboniferous Shallow-Marine Gas Sands in Algeria
Gas sands within black shale sequence are difficult to correlate
Seismic, wireline, and biostratigraphic data lack resolution
Key Elemental Ratio ProfilesChemostratigraphic Zonation Based on Shales
Binary & Ternary Plots AllowDiscrimination of Chemostratigraphic Units
Two-Well CorrelationChemostratigraphic Zonation Based on Shales
Solution: Greatly Improved CorrelationUtilizing Chemostratigraphy
11 chemostratigraphic units give better correlation of reservoir sands
Correlation is valid for almost 700 meters of section over a distance of 17 kilometers
ED-XRF
Wellsite Analytical Instrumentation
LIBS
Data in20-30 minutesfrom cuttings
Improved Geosteering Results Devonian Limestone Reservoir in Canada
Gas flow was doubled from 1.2 to 2.5 MMCFD
Only one extra day of rig time required in a time-critical situation
200 meters of additional wellbore exposure to the reservoir was achieved
Improved Geosteering Results Devonian Limestone Reservoir in Canada
Shales Contain Highest Amount ofChemostratigraphic Information!
From Jürgen Schieber Website
Devonian Shale Study in Western New YorkCore Locations & Stratigraphic Intervals
WVAN
From Sagemon et al. 2003
Ti/Al10-pt MA
CaCO3wt%
13Corg
‰ vs. PDB
TOCwt% Lithofacies
Sageman et al. (2003)
9 elements
TOC
CaCO3
StandardChemostratigraphicStudy on Shale
50-55 elements
TOC
Marcellus Interval12 meters = 39 feet
Geochemical ProfilesMarcellus Shale in Western New York
From Sagemon et al. 2003
Chemostratigraphic ZonationMarcellus Shale in Western New York
S1
M1
M5
M7
M3M2
M4
M8
M6
S2
Modified from Sagemon et al. 2003
Differentiation of Chemostratigraphic UnitsMarcellus Shale in Western New York
200
250
300
350
400
450
500
0 50 100 150 200 250 300 350 400 450
Mo (ppm)
V +
Cr (
ppm
)
M4
M5 + M6
Data from Sagemon et al. 2003
0
50
100
150
200
250
300
350
400
450
0 2 4 6 8 10 12 14 16 18
TOC (wt%)
Mo
(ppm
)
Mo & TOC RelationshipMarcellus Shale in Western New York
Data from Sagemon et al. 2003
Chemostratigraphic ZonationOhio Shale in Eastern Kentucky (Algeo 2004)
Mo & TOC RelationshipsOhio Shale in Eastern Kentucky (Rimmer 2004)
STFM
LPFM
NNEM
Elemental Composition
Mineralogical Composition
Organic Composition
Flow Properties
Geomechanical Properties
Construct Predictive Elemental Modelfrom Comprehensive Gas Shale Data Set
LIBSCalibration
Elemental Analysis While DrillingImmediate Input for Improved Frac Design
LIBSMeasurement
Chemosteering®
Mineralogy
Geomechanical Parameters
Late carbonate fracture-filling will likely have relatively high Fe2 O3 + MgO + MnO, and may be recognizable
Need large contrast in mineralogy and elemental composition between carbonate fracture-filling and host rock
Most black shales have high Al2 O3 and TOC, low CaO + MgO + MnO – good chance?
Quartzose tight gas sandstones have very high SiO2 , very low CaO + MgO + MnO – good chance for Travis Peak
Recognition of Carbonate-Filled Fractures in Gas Shales Based on Elemental Data?
Calibrate against petrographic data based on technique of Laubach (2003)
Microfractures and remnant pores in quartzose sandstone are sealed by
late ankerite cement.High degradation - Poor fracture
quality predicted.
Scanned Cathodoluminescence (CL) ImagesFrom Rob Reed’s CL Web SiteBureau of Economic GeologyAustin, Texas, United States
Microfractures and remnant pores in quartzose sandstone are partially
open, no late ankerite cement.Low degradation - Good fracture
quality predicted.
Petrographic Fracture Degradation DataCretaceous Travis Peak Sandstone in Texas
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80 90 100
Ankerite Fracture Degradation Dg (%)
Ank
erite
Cem
ent
(vol
%)
Ankerite Threshold= 2.3 vol%
Above Threshold Average Dg =80.6 ± 21.0 %
Below Threshold Average Dg =23.1 ± 30.6 %
High Average Degradation
Poor Fracture QualityProbably Not Productive
Low Average Degradation
Good Fracture QualityProbably Productive
Petrographic data courtesy of Steve Laubach & Julia Gale
Calibrated Elemental Data for Fracture PredictionCretaceous Travis Peak Sandstone in Texas
0
1
2
3
4
5
6
7
0 10 20 30 40 50 60 70 80 90 100
Ankerite Fracture Degradation Dg (%)
MnO
+ M
gO +
CaO
(w
t%)
Above Threshold Average Dg =74.6 ± 28.6 %
MnO + MgO + CaOThreshold = 1.30 wt%
Below Threshold Average Dg =29.4 ± 35.0 %
High Degradation
Poor Fracture QualityProbably Not Productive
Low Degradation
Good Fracture QualityProbably Productive
Petrographic data courtesy of Steve Laubach & Julia Gale
Rare EarthElements
Wellbore Placement
Formation Evaluation
Elemental Applications for E&P
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