From Resources and Reserves to Carbon Isotope Anomalies · 2015. 12. 16. · Traditional Coalbed Gas Total Pot. Region’s Resources Resources Resources Proportion PGC Area (Mean,

U.S. Shale GasFrom Resources and Reserves to Carbon Isotope Anomalies

John B. CurtisPotential Gas AgencyColorado School of Mines

Major U.S. Basins and Shale Plays c. 2007(Where are the Haynesville and Marcellus???)

Shale Gas Annual Production and Energy Information Administration (EIA) Forecast

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CUMEIA Projection

EnCana

U.S. Shale Gas Annual Production from Five Classic Plays to 2007

Modified and updated from Hill and Nelson, 2000

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New AlbanyLewisBarnettAntrimOhio

Expiration ofSection 29 Tax Credit

EnCana

Targeted Research – $150 Million

http://www.nap.edu/?isbn=0309074487�

http://images.google.ca/imgres?imgurl=http://www.gepllc.com/images/epri/products/Process/CPNG/flame.jpg&imgrefurl=http://www.gepllc.com/epri_retail_targets_process_CPNG.php&h=170&w=143&sz=4&hl=en&start=11&tbnid=-83WvpcR4RZYdM:&tbnh=99&tbnw=83&prev=/images%3Fq%3D%22gas%2Bresearch%2Binstitute%22%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Dactive%26sa%3DN�

http://www.energy.gov/index.htm�

Acquisitions – >$8 Billion

Source: Trollart.com – Ray Troll

Resource Development – >$15 Billion

Source:devonenergy.com

Source:devonenergy.com

Source:AAPG

Source:AAPG

Source:chiefoiland gas.com

Hydrocarbons From Shale – Never Say Die

Growth in Barnett Shale - Ft. Worth Basin

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ucin

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ells

Gas Production Well Count

Presenter

Presentation Notes

Low-magnification view exhibits darker, more carbonaceous mudstone texture. Thinly laminated siliceous/argillaceous matrix hosts a mix of organic material, microcrystalline clay, silica, angular to subrounded silt, micromicas, phosphatic debris, and microfossil fragments. White, patchy chert is primarily recrystallized biotic components, especially forams and radiolarians (arrows). Magenta epoxy highlights an induced, layer-parallel microfracture. (Plane-polarized light. Scale bar = 0.5 mm)

Exploration Considerations

• Natural fractures - Friend or Foe?• Facies changes - greater permeability• Kerogen type - I,II,IIS,III• Microbial or thermogenic gas?• Thermal maturation history• MWD - especially w/ gas isotopes

Geochemical Properties of Gas Shales

Modified from Hill and Nelson, 2000

Modified from original work by Ira Pasternack

Evolution of Antrim Shale Gas

Some Elements of a Successful Shale Gas Play

Productivity

Gas-In-PlaceThickness

Organic Richness Maturation

Brittleness

Mineralogy Permeability

Pore Pressure

Potential Supply of Natural Gas in the United States

Report of thePotential Gas Committee(December 31, 2008)

Presenter

Presentation Notes

The PGC consists of 145 volunteer geologists and engineers who assess the amount of remaining U.S. natural gas resources every two years. The Committee has been completing these assessments since 1964. The (December 31, 2008) refers to the last data collected, i.e., drilling, production, geologic and geophysical data were used that were available up to that date. The analyses are then completed and the report is published the following year. The members that complete the assessment use public and private data and appropriate methodologies to provide a geological look at our natural gas endowment. They are selected for their expertise in working the appropriate geological basins.

Proved Reserves vs Resources

• Known gas reservoirs

• Existing economic conditions

• Existing operating conditions

• Discovered

• Undiscovered

• Effects of technology

• Effects of economics

POTENTIAL GAS AGENCY

COLORADO SCHOOL OF MINES

Presenter

Presentation Notes

The Potential Gas Committee reports technically recoverable resources - a geological look at our remaining natural gas endowment. We assume neither a time schedule nor a specific market price for the discovery and production of future gas supply. Our assessment is separate from and does not include Proved Reserves, which are reported annually by the EIA of US DOE.

Regional Resource Assessment

Data source: Potential Gas Committee (2009)

Traditional 1,673.4 TcfCoalbed 163.0 TcfTotal U.S. 1,836.4 Tcf

353.517.3

455.23.4

24.016.6

193.857.0

51.32.6

274.97.5

374.451.9

PGC Resource Assessments, 1990-2008


Total Potential Gas Resources (mean values)

Possible Constraints on Future Gas Supply

Sufficient Supply toMeet Demand

TechnologyResourceBase

EnvironmentalConcerns

Skilled Workforce

Regulatory &Land Issues

Gas Price PipelineCapacity

Rig Availability

Gas Character Anomalies Found in Highly Productive Shale Gas Wells

John E. Zumberge1

Kevin A. Ferworn1

John B. Curtis2

1GeoMark Research Ltd., Houston, Texas USA2Colorado School of Mines, Golden, Colorado USA

Pres enta tion Outline

• Background: carbon isotope fractionation; gas wetness and wellsite sample collection during drilling;

• I. Ethane isotope “rollover,” suggestive of in situ gas cracking and more productive wells;

• II. Mud gas isotope “reversals,” indicative of overpressured shales;

• III. Permeability markers from differences in methane isotopic composition between mud (free) and cuttings (adsorbed) gases.

Background

Dry Gas and Wet Gas Compos itions

Wells ite Sampling for Gas Is o topes

mud gas sampling manifold

IsoTube for mud gases

IsoJar for cuttings gases

Mud Gas and Cuttings Sampling

Changes in Carbon Is o tope Ra tios with Thermal Matura tion (afte r M. Schoell)

After M. Schoell

I. Barne tt Sha le Ethane Is o tope “Rollover”

C2 isotope “rollover”

Normal increasing maturity trend

Ethane isotope reversals in

mature eastern Barnett gases

Barne tt Ethane Is o tope “Rollover”

Normal maturity trendEthane isotope reversal

Stabilized Produc tion vs Wetnes sStabilized Production vs. Gas Wetness

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C2 Isotope“Rollover”C2 Isotope“Rollover”

Wells without isotope “rollover”are never the best producers.

Poorly producing “rollover” wells are often earlier completions. Low TOC and rock properties are also important issues.

Summary - Ethane Is o tope “Rollover”

• Ethane (and propane) isotope “rollover” occurs in increasingly high-maturity shale-gas wells.

• Behavior is also observed in numerous other gas shales in other basins.

• These wells appear to be among the most productive shale-gas wells:• ? In situ cracking increases the number of smaller

molecules, increasing fluid pressure.• ? Organic material becomes more brittle, leading to

increased kerogen porosity and permeability.

II. Mud Gas Ethane Is o tope “Revers a ls ”

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Ethane Carbon Isotope, δ13C (‰ )

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epth

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Wetness, (C2 - nC5) / (C1 - nC5)

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epth

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Bossier / Cotton ValleyHaynesville top of overpressure

Haynesville Example

“normal” maturity isotopic trend

Barne tt Sha le S tra tigraphy

Haynesville

Eas t Texas /North La . Oil Dis tribu tion

Jurassic Carbonate SourceJurassic/Cretaceous Reservoirs

Cretaceous Shale SourceCretaceous Reservoirs

Tertiary Shale Source & Reservoir

East Texas Field

Haynes ville -Bos s ie r

III. Sha le Gas Is o topes asPermeability Markers

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epth

Headspace Gas - IsoJars

Mud Gas - IsoTubes

MoreFreeGas

More AdsorbedGas

Methane Carbon Isotope

A clear isotopic difference existsbetween methane from mud gases(black squares) and methane fromheadspace gases (red squares).

• Mud gas ~ Free / solution / lost gas

• Headspace gas ~ Adsorbed gas

Larger differences between IsoTube And IsoJar isotopes correlate with increased permeability.

Well Log Evidence for Poros ity/Permeability Detec tion from Sha le Gas Is o topes

1 2 3 4GR

dt

DEPTH(AT10_) ISOJARS

ISOTUBESAT20CHMN -20

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GAP0 150

Zones of maximum porosity /

permeability

Shale Gas Analys es as Permeability Markers – Poorer Permeability

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epth


Mud Gas - IsoTubes

MoreFreeGas

More AdsorbedGas


Poorer permeability:Gas eventually evolving off cuttings has more free gas, making methane isotopes more negative.

Headspace Gas

Mud Gas

Free Gas (more negative isotopes)

Adsorbed Gas (more positive isotopes)

Shale Gas Analys es as Permeability Markers – Bette r Permeability

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Mud Gas - IsoTubes

MoreFreeGas

More AdsorbedGas


Free Gas (more negative isotopes)

Adsorbed Gas (more positive isotopes)

Better permeability:Gas eventually evolving off cuttings is mostly adsorbed gas.

Headspace Gas

Mud Gas

Conclus ions

• Shale-gas well performance can be correlated to gas character anomalies seen in produced, mud and headspace gas isotopic analyses:– Ethane and propane isotope “rollovers”

indicate in situ cracking at high maturities. – Ethane isotope “reversals” within a single well

demonstrate overpressure/effective seals.– Mud (free) and headspace (adsorbed)

methane isotopic signatures can be used as permeability markers.

Potential Gas Agency

Traditional Coalbed Gas Total Pot. Region’sResources Resources Resources Proportion

PGC Area (Mean, Tcf) (M.L., Tcf) (Tcf) of Total L48

Regional Resource Assessment Summary

Gulf Coast 455.2 3.4 458.5 28.1%Rocky Mountain 374.4 51.9 426.3 26.1%Atlantic 353.5 17.3 370.8 22.7%Mid-Continent 274.9 7.5 282.4 17.3%Pacific 51.3 2.6 53.8 3.3%North Central 24.0 16.6 40.6 2.5%Total Lower 48* 1,484.9 99.2 1,632.5

Alaska 193.8 57.0 250.8Total U.S. (means)* 1,673.4 163.0 1,836.4

Data source: Potential Gas Committee (2009) * Separately aggregated total, not arithmetically additive.

Presenter

Presentation Notes

The next three slides summarize the information for the 89 geological provinces into seven areas. The individual province values may be found in the Advance Summary.

Regional Resource Comparison


PGC Resource Assessment 2008


ProbableResources Possible

Resources

SpeculativeResources

Probable (existing fields) 441.4 TcfPossible (new fields) 736.9 TcfSpeculative (frontier) 500.7 TcfTotal 1,673.4 Tcf

Total Traditional Resources (mean values) by category

PGC Resource Assessment 2008


ProbableResources

PossibleResources

SpeculativeResources

Probable (existing fields) 14.2 TcfPossible (new fields) 49.8 TcfSpeculative (frontier) 98.9 TcfTotal 163.0 Tcf

Total Coalbed Gas Resources (mean values) by category

Documents

From Resources and Reserves to Carbon Isotope Anomalies · 2015. 12. 16. · Traditional Coalbed Gas Total Pot. Region’s Resources Resources Resources Proportion PGC Area (Mean,