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