Techniques and Technology in the Evaluation of Unconventional

Shale Gas Resources

Robert S. KuchinskiWeatherford Oil Tool Middle East

3rd India Unconventional Gas Forum (IUGF) - 2013

Mumbai, IndiaJanuary 18, 2013

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• I would like to express my gratitude to the following organizations for making this presentation possible:– The organizers of the 3rd India Unconventional Gas

Forum (IUGF) - 2013 – Weatherford India

Acknowledgements

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• Not all shale reservoirs are alike• Must understand core area of shale play• Completion costs consume 50 to 60% of well

costs…and rising• Continuous learning thru data acquisition at

every phase of well life is essential to maximize recovery from these reservoirs

Key Learning’s from North America

Unconventional: Satisfaction Survey

TOTAL SAMPLE

BARNETT SHALE

MID-CONTINENT

GULF COAST

ROCKIES

WILLISTON/ BAKKEN

MARCELLUS/ UTICA SHALE

PERMIAN BASIN

EAGLE FORD SHALE

HAYNESVILLE + FAYETTEVILLE

CANADA

INTERNATIONAL

0% 10% 20% 30% 40% 50%

24%

47%

35%

33%

32%

30%

25%

22%

21%

21%

19%

19%

Source: Welling & Company

SHARE OF FRAC JOBS NOT MEETING PERFORMANCE EXPECTATIONS

Root Cause to Challenges in Unconventional Exploitation

FAILURE TO UNDERSTAND SUBSURFACE

POOR FRAC DESIGN

DOWNHOLE EQUIPMENT/ TOOLS

INEXPERIENCED CREWS / HUMAN ERROR

SURFACE EQUIPMENT

GEL NOT BROKEN UP

0% 20% 40% 60% 80%

73%

18%

14%

13%

12%

1%

ROOT CAUSE OF FRAC JOBS NOT MEETING PERFORMANCE EXPECTATIONS

Source: Welling & Company

Shale Fabric Analysis

Ultra-Thin Sections

2D Nano-Scale ImagingElemental Fabric Mapping

“Shale Reservoirs have large variation”

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Evaluation of Unconventional Resources

Gus Archie 1907-1978

Increasing Gamma Ray

Increasing Intragranular Porosity

Intergranular Porosity and disassociation between rock and fluid

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Evaluation of Unconventional ResourcesClean Gas Sandstone Minimal Clay Higher Energy Depositional

Environment Coarse grained -Well Sorted Favorable Porosity and

Permeability Diagenesis can limit K Log evaluation based on the

disassociation between fluid and rock

Unconventional Clastic Gas Variable Clay Content Log evaluation not useful for fluid

determination Rocks required to complete

analysis Rocks and fluid associated

Shaley Gas Sandstone Finer grain size and

presence of clay reduce K Clay content disrupts Sw

Calculation Sw equations modified to

cope with clay Logs required for

mechanical properties Hydraulic fracturing

becomes be necessary Diagenesis can limit K and

mineralogy

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• Critical to Understand the Resource Quality and to be able to grade it.– What is extent of the Core Area?

• The Arial sweet spot• Highest concentration of gas• Most productive• Lowest cost to develop• Most valuable

– What other areas are productive?• Gas concentration and Productivity vs. Core Area?

– What is the extent of the fringe area?• What is Gas concentration and Productivity?

The Core Area

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2011 Shale AFE Breakdown

10,500’ TVD14,100’ MD

3,600’ Lateral 12 Stages

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10,500’ TVD15,500’ MD

5,000’ Lateral 16 Stages

2012 Shale AFE Breakdown

Resource Play Formation Evaluation

Uranium content TOC

Elemental analysis Brittleness evaluation

Detailed gas composition Delineates top and bottom of reservoir

DTS and DTC Geomechanical Attributes

Borehole image Natural fracture network

Rock Properties Organic richness and Gas in place

Hydraulic Frac extent Productivity index

Extensive core in labs and cutting evaluation in labs at wellsite while drilling

Key Parameters

Key downhole logging measurements

• TOC Measures the present day organic richness of a rock• Empirical relationship to Uranium content• Maturation parameters are indicative of the maximum paleo-

temperature that a source rock has reached• The standard for maturity reporting is Vitrinite Reflectance (% Ro)

Quality TOC (wt%)Poor <0.5Fair 0.5 to 1Good 1 to 2Very good 2 to 4Excellent >4

Vitrinite Reflectance (Ro)

Immature <0.6%Oil Window 0.6-1.1%Wet Gas Window 1.1-1.4%Dry Gas Window 1.4-~3.2%Gas Destruction >~3.2%

Shale As a Reservoir Rock

Ro > 1.5%: This level avoids unfavorable relative permeability effects caused by oil blocking small pore throats and permeability

TOC > 2.0%: This level allows for the generation of abundant gas

GRI Devonian Study: Uranium vs. Kerogen (TOC)

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Characteristics of Shale Units in Different Basins

Cambay K G Cauvery AssamArakan

Vindhyan Gondwana

TOC %1.5-4.0 1.2-

23.00.31-4.76 2.5-6.2 0.60-6.04 4.00->10

Vro%0.53-0.85 0.35-

1.300.34-1.15 0.57-1.94 No data 0.40-1.20

Thickness in Meters 400-

>1500500-1800

200-1100 800-1200 75-320 150-900

K erogenType II & I I I I I & I I I I I & I I I I I & I I I I I I I I I

Prognosticated Resource Potential (Tcf)

217 280 80 55 Not known

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The Shale’s of India

Source Oil & Maritine Journal by Dr. V.K. Rao

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• In addition to Knowledge of TOC and RO….favorable Reservoir Properties must be present:– Porosity > 3%– High reservoir pressure

• Pack in more gas• Keep fractures open

– Favorable In Situ Stress• Influences the permeability and the response to

hydraulic fracturing• Understanding the mineralogy is essential to understand

brittleness

Shale As a Reservoir Rock

Identification of Ductile Zones from Mineralogy

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Initiation of a frac proved unsuccessful in this zone with >50% claysClays

1 sample per 20’

MINERALOGYQuartzCarbonatesClaysOthers

TPH / TOC (0-10)S1S2TOC

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Events located by horizontal and vertical arrays.

Treatment Well 8-12

Treatment and Observation Well 1-12

Treatment Well 16-1

Microseismic

…….to Improve Frac Program Design

Understanding Fracture Growth…..

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• Second most important item next to establishing core area

• Need relentless pursuit of efficiencies and cost reductions

• Shale plays will require thousands of wells drilled over decades

• Must first establish the most efficient manufacturing design

• Early attention to best practices, appropriate to the specific shale play and emphasis on continuous learning are key

• Development of effective multidisciplinary teams

Continuous Learning

Summary• Variability of shale is a fundamental controlling

factor on weather a shale deposit will produce economic quantities of natural gas.

• Variations within a shale deposit will determine the core area of a shale play and thus the value assigned to different locations within a shale play.

• Following a process of “Good Science” allows for “Good Engineering” throughout the various stages of a shale project.

• Continuous learning and refinement is a must in order to maintain economic viability.

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Questions

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