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Bakken and Three Forks Logging Acquisition for Reservoir Characterization and Completion Optimization

Ernest Gomez (egomez@denver.oilfield.slb.com), Peter Hook, Peter S. Kaufman and Stephen D. Sturm

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Acknowledgements

• Bakken Consortium Members

– XTO (Headington)– Brigham– Continental – Encore– Hess– Petro-Hunt– Whiting

• Schlumberger

• North Dakota Oil and Gas Research Council

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Outline

• Takeaways

• Target Identification– Fractures

– Lithology

– Porosity and permeability

• Stimulation Optimization– Rock properties

• Recommendations/Summary

Qtz

Ls

Dol

Illite

Fld

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Takeaways• Bakken and Three Forks

properties are variable:– Lithology

– Fractures

– Matrix

– 3-D rock mechanical

• Measurement of these properties is important and can be used for:

– Target identification

– Model and optimize completions

XTONesson State 42-36X

(Three Forks)

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Role of Core

• Serves as calibration for logging suites

– Lithology (XRD)

– Petrophysical properties (Ф, k and Sw)

– Anisotropic mechanical rock properties (YM, PR, UCS, stress)

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Target Identification

• Fractures

• Lithology

• Matrix– Porosity

– Permeability Qtz

Ls

Dol

Illite

Fld

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FMI (Fullbore Formation MicroImager)Fracture CharacterizationHorizontal Well• Fracture orientation, density, aperture

and spacing • Identification of fracture swarms for

completion design• Multi-axis caliper for swell packer

design• Identify lateral lithology variations

• Stratigraphic, structure and stress azimuth information

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FMI - Nesson State 44X-36

Fractures• Natural fractures sparse• Occur In limestones (ELAN –

ECS) and zones of higher curvature

• Fracture permeability: microdarcy - nanodarcy

• Fracture porosity: 0.004% net phi

• Induced fractures

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ECS (Elemental Capture Spectroscopy Sonde)Lithology

Vertical and Horizontal Well• Lateral target selection – used

in ELAN for pay evaluation• Carbonate/Clastic lithology

identification

• Clay volume

• Improved lithology - better mechanical properties and improved frac design

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ECS – Nesson State 42X-36

UpperBakken

MiddleBakken

LowerBakken

Al Si Ca SFe

GR

ThreeForks

Clay

Clastic Carbonate

Pyrite

Lithology

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CMR (Combinable Magnetic Resonance)Porosity and Permeability

Vertical Well• Lithology independent porosity

and permeability• Horizontal placement - used with

ELAN for complete pay evaluation

• Combinable with other logging tools – lower rig costs

• Good resolution of laminated sediments (Three Forks)

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CMR - Porosity Definitions

T2 Distribution - Main output of CMRT20.3ms 3.0ms 33ms

CMFF (%)CMRP_3MS (%)

TCMR (%)

LOG_T2CUTOFF

3000ms

T2 Distribution0.3ms 3000ms

Three porosity measurements give an indication of the

types of porosity which are present.

CapillaryBound

Porosity

Small PorePorosity

Free FluidPorosity (Producible

Fluids)Total Porosity Area

under Distribution

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CMR – Nesson State 42X-36 (Vertical)

LowerBakken

UpperBakken

MiddleBakken

ThreeForks

GRФ k10% 1 mD

Middle Bakken• Best Ф and k

developed in dolomitic sediments

• Decrease in Ф and k toward base

Three Forks• Best Ф and k developed

in laminated sediments (dolomite and mudstone) at top

• In general better Ф and k than Bakken; more dolomite

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Lithology and Matrix Results - Nesson State 42X-36Ф k

FldQtz

Ls

Dol

Illite

Dol

LowerBakken

UpperBakken

MiddleBakken

ThreeForks

• Detailed lithology (ELAN) tied to core and ECS• Porosity and permeability tied to core and CMR

Lithology(Dry Weight %) 30%

10 mD0.010%

Pyr

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• Provides low cost way of acquiring information in laterals

• Pumped down inside drill pipe

• When calibrated to core and vertical logs from pilot well can be used to determine:

– Lithology

– Porosity (reserves)

• Used in hydraulic fracture stage selection or swell packer placement

Clay

Quartz Porosity

Calcite

Reservoir Saturation Tool (RST)(Reservoir Characterization)

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Stimulation Optimization

• Mechanical Rock Properties– Containment

– Planning

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Sonic Scanner(3-D Rock Mechanical Properties)

• Stress orientation (SH)

• Stress magnitude

• Anisotropic mechanical rock properties

– Young’s Modulus

– Poisson’s Ratio

• Input for hydraulic fracture modeling and optimization

TOC

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Sonic Scanner - 3-D Rock Mechanics

Large stress difference due

to shale layering

Young’s Modulus and PR differ by

80%

In this well hydraulicfracture containment

provided byBakken Shales

0.73/0.81

0.73/0.73

0.73/0.89

Upper Bakken

MiddleBakken

LowerBakken

ThreeForks

Young’sModulus PR

AnisoStress

GR

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Multi Stage – Nesson State 44X-3610

900

1150

0

1315

0

Fractures

TXSP Aniso

% Carbonate

GR

1125

0

1220

0

1250

0

1345

0

1380

0

Stage 1Stage 6 Stage 5 Stage 4 Stage 3 Stage 2

PackerIn Target Perforations

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Recommended Logging Suite - Vertical

• Vertical Pilot (first 1 to 2 wells in an area)

– PEx (Resistivity and Porosity)

– ECS (Lithology)

– CMR (Porosity and Permeability)

– RST (Reservoir Characterization)

– Sonic Scanner (SH and Vertical Hydraulic Fracture Containment)

– Core

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Recommended Logging Suite - Laterals

• Lateral (first 1 to 2 wells in an area)

– FMI (Fracture Characterization)

– ECS – Sonic Scanner– RST

• Lateral (Development)– RST

MD

TVD

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Summary• Core calibrated log measurements in the Bakken

and Three Forks can lead to a better understanding of :

– Fractures– Porosity– Permeability– Lithology– Anisotropic mechanical rock properties and

stress profile • These log measurements can be used to model

and optimize stimulations