gas shale primer - east west petroleum€¦ · gas and oil producing shale and nonconventional oil...

Gas and Oil Producing Shale

and Nonconventional Oil

Opportunity with Knowledge

and Technology

r. marc bustin

DEFINITION OF

UNCONVENTIONAL RESOURCES

• hydrocarbon distribution controlled not necessarily by

buoyancy – no obvious reservoir seal– Low Matrix Permeabilities (<0.1 md) or high viscosity fluids

– Adsorption Mechanisms and diffusion maybe important

– Pressures maybe abnormal

• economic recovery require non-standard exploration and

operating practices– Geomechanics and geochemistry disproportionally important in delineating

sweet spots

– Wellbore and Completion Designs

– Well and Formation Testing Procedures

– Development Strategies

UNCONVENTIONAL GAS AND

RESOURCE PLAYS

TIGHT GAS SANDS

• Continuous Deposition

• Low Permeability

• Both Traditional and “Basin-Center” Settings

COALBED METHANE

• Self-Sourcing Reservoir

• Gas Adsorbed in Coal

• Requires Depressuring and Usually Dewatering

GAS and Oil Prod. SHALES

• Self-Sourcing Plus Traditional Porosity Reservoirs

• Gas Adsorbed in Organic Matter

• Requires Pervasive Natural Fract. Network or K pathways

RESOURCEPLAYS

Kuuskraa, 2006

METHANE

HYDRATES

UNCONVENTIONAL GAS AND

RESOURCE PLAYS

TIGHT GAS SANDS

• Continuous Deposition

• Low Permeability

• Both Traditional and “Basin-Center” Settings

COALBED METHANE

• Self-Sourcing Reservoir

• Gas Adsorbed in Coal

• Requires Depressuring and Usually Dewatering

GAS and Oil Prod. SHALES

• Self-Sourcing Plus Traditional Porosity Reservoirs

• Gas Adsorbed in Organic Matter

• Requires Pervasive Natural Fract. Network or K pathways

RESOURCEPLAYS

Kuuskraa, 2006

METHANE

HYDRATES

opportunity

unconventional

reservoir rock

conventional

reservoir rock

UNCONVENTIONAL OIL PLAYS

modified form Russum, 2010

Conventional Oil in Unconventional Rocks

Unconventional Oil in Conventional Rocks

Russum, 2010

0

opportunity

opportunityopportunity

opportunity - understanding and

evaluating rock systems and application of

appropriate technologies can result in

commercial exploitation of hydrocarbon

resources previously considered sub

economic

assess to opportunity- network of

contacts and companies who want to do

business and savvy to make it work

East-West Competitive Advantage

• experienced technical professionals –

access to ideas, technology and innovation

• strong committed board of directors

• business savvy

• strong and very very aggressive financial

support

• access to opportunity- strong land position

and access to much more

GAS SHALES- source rocks with retained HCs

Cap Rock

Source Rock

Reservoir Rock

Gas

Oil

Gas and Oil

Burial ofOrganic Rocks

Kerogen

Biogenic Gas

ThermogenicGas and Oil

Wet Gas

Dry Gas

background

Oil & Gas Shales- source rocks with retained HCs


Cap Rock

Source Rock

Reservoir Rock

Gas

Oil

Gas and Oil


Kerogen

Biogenic Gas


Wet Gas

Dry Gas

Antrim

Eagleford

Haynesv.


background

Green

River



heavy oilreservoir access

tight rock


Cap Rock

Source Rock

Reservoir Rock

Gas

Oil

Gas and Oil


Kerogen

Biogenic Gas


Wet Gas

Dry Gas

Antrim

Eagleford

Haynesv.

0.38 nm

background


Complexities and Predictions

ANTRIM SHALELEWIS SHALEOHIO SHALE

facies controlled permeability

fracture or fraced controlled permeability

haynesville barnett fayetville woodford ohio lewis

montney eagle ford

background

Definition: Gas/Oil Shale

• Shale gas/oil is defined as a fine grained reservoir in which gas/oil is self sourced and some of the gas is stored in the sorbed state

• Sorbed gas is predominately stored in the organic fraction– so organics present

• Not just ‘shale’Bustin, 2005, AAPG

Background

Clay <2 um

Silt <62.6>2 um

limestone ie. Eagle Ford, Muskwa

dolomite ie. Montney

chert ie Woodford

mudstone ie.Marcellus, Muskwa

siltstone/vfg sandsone ie. Lewis

shale ie. Anrtrim

Classify Petroleum Systems as

Conventional …

USGS 2003

…or Continuous

USGS 2003

Characteristics of ‘Continuous’

Accumulations• Regional in extent

• Diffuse boundaries

• Low matrix permeabilities

• No obvious seals or traps

• No hydrocarbon/water contacts

• Close to or are source rocks with non expelled hydrocarbons

• Low recovery factors

• Includes tight sandstones, coalbed gas, oil and gas in shale and chalk

NATURAL GAS PYRAMID

HighQuality

Medium Quality

Low Quality

Tight Gas Sands

CBM Gas Shale

Low Btu Gas Hydrates / Other

1000 md

100 md

1 md

0.00001 mdProduced

Reserves

Undiscovered Resources

New Fields CBM

Tight Gas Gas Shales Low Btu

Emerging / Future ResourcesSub-Volcanic New Gas Shale New Tight Gas

Deep CBM Basin-Center

Gas Hydrates / Other

technology price

0.5 mm

Eagle Ford Shale

Wet Barnett

Wet Marcellus

Duvernay

Implications of the New Gas Shale World

What are the World Gas Shale

Resources and Reserves?

estimates based on source rock studies with

assumptions about how much gas retained in source

rocks

-Rogner 1997 estimate Resource Endowment at 16,119

TCF

-US NPC estimates total unconventional at about 32 000

TCF

-IEA World Energy Endowment assumes 40% of

endowment is recoverable – 6350 TCF

-so we are pretty much making intelligent guesses.....

US NPC SPE 68755

Region Coalbed

Methane (TCF)

Shale Gas

(TCF)

Tight Gas

(TCF)

Total

(TCF)

North America 3017 3842 1371 8228

Latin America 39 2117 1293 3448

Western Europe 157 510 353 1019

Central and East

Europe

118 39 78 235

Former Soviet Union 3957 627 901 5485

Mid East & North

Africa

0 2548 823 3370

Sub-Saharan Africa 39 274 784 1097

Centrally planned Asia

and China

1215 3528 353 5094

Pacific (OECD) 471 2313 705 3487

Other Asia Pacific 0 314 549 862

South Asia 39 0 196 235

World 9051 16112 7406 32560

Estimates of World Wide Distribution of Unconventional Gas Resources

Source: "Tight Gas Sands", Journal of Petroleum Technology, June 2006, Page 86-93.

Table 1 - Distribution of Worldwide Unconventional-gas resources (After Rogner 1996, Taken from Kawata and Fujita 2001)

North American Gas Production Forcast

EnCana, 2010, IP

Producing Shale

Plays

Horn River100-150 Bcf/sect.

Montney100 Bcf/sect.

Barnett140-160

Bcf/sect.

Fayetteville25-65 Bcf/sect.

Haynesville150-200 Bcf/sect.

Marcellus45 Bcf/sect.

Woodford100 Bcf/sect.

Antrim6-15 Bcf/sect.

Utica45 Bcf/sect.

Lewis40 Bcf/sect.

Ohio5-10Bcf/sect.

New Albany7-10Bcf/sect.

Eagle Ford50-150 Bcf/sect.

Duvernay? Bcf/sect.

? Oil

green denotes

liquids production

based map

modified from

EnCana IP. 2009

TransCanada Pipeline (June 2010, Investor Presentation)

Projected Gas Supply –TransCanada Pipeline

EnCana Investor Presentation, 2010

Range Resources, April 2010

Trend to fewer wells with longer lateral lengths

with more frac stages

Southwest Energy, March 2010

the learning curve

continues

to flatten

The costs of shale gas

Source: Chesapeake Energy:

January 2010 Investor Presentation

Source: Vello Kuuskraa, President of ARI Inc, in presentation to the Copenhagen summit, 12

December 2009

Horsfield and Schulz, 2010 AAPG

Conventional Gas Distribution

Source: Oil and Gas Journal

unconventional opportunities exist where ever

conventional production exists

and many other areas

Geological Characteristics Common to

Producing Gas and Oil Producing Shales

• Organic rich

• Marine to transitional marine

• Interbedded source and seal

• Comparatively thick

• Permeability enhanced by fracturing

or interbedded facies with higher

perm.

What gas/oil shale properties are

important?

• gas/liquid composition

• gas and liquid capacity and content-sorbed and free gas

• permeability- fracture or facies controlled

• thickness

• lateral extent

• ease of completion, reservoir access

gas and oil producing shales

• producing shales range from organic rich,

fine grained rocks such as the Antrim or

Ohio Shale to variable facies rocks such

as the Lewis Shale

Background

Ohio

Lewis

Background

New Albany

SOME EXAMPLES

Barnett

Antrim

TEM

50 000 nm

SEM

Background

Shales are heterogeneous rocks

200 000 nm

Outcrop

Hand

Spec.

Light

FESEM

200 nm

http://ccm.geoscienceworld.org/content/vol52/issue5/images/large/08-08.jpeg

4500

Background

Pressure and Temperature Space of

Producing Shales

0 20 40 60 80 140

0

1500

3000

Temperature ºC

Barnett

LewisOhio

New AlbanyAntrim

Pre

ss

ure

(PS

IA) Woodford

Caney

Fayetteville

Eagle Ford

Muskwa

Haynesville

Utica

Marcellus

Maturity and Organic Matter Content

Background

1.6

Antrim

New Albany

Barnett

BIOGENIC GAS

OIL WINDOWRom

ax

( %)

0

0.4

0.8

1.2

TOC (%)

0 4 8 12 16 20 24

THERMOGENIC GAS

Woodford

Caney

Fayetteville

Muskwa

2.0

Haynes-ville

Eagle Ford

Utica

Marcellus

Ohio

Lewis


ANTRIM SHALE

LEWIS SHALEOHIO SHALE

facies controlled permeability

fracture or fraced controlled permeability

Mu

skw

a/O

tte

r P

ark

/Evie

No

rdeg

g

Bu

ckin

gh

ors

e

Sh

aft

sb

ury

Mo

ntn

ey


ANTRIM SHALE

LEWIS SHALEOHIO SHALE

Tight SSTrue Shale/Porcellanite

What We Know!

• rocks referred to as gas/oil shales

range from true shales to tight sands

• individual formations, members or

units within a shale unit may be

extremely heterogeneous in

mineralogy and fabric and hence pore

system and flow characteristics

Shale

Mapping TOC

ThicknessTOC

Geochemistry

Gas CapacitiesAdsorbed Gas

Free Gas Solution Gas

Producibility

Moisture

Maturity

Al2O3 fraction

Fracturing

Temperature

Pressure

Area

PorositySedimentology

Diagenesis Silica contentsCoarser horizons

Gas/Oil Shale Model

So, Sg, Sw,

Permeability

Wireline logs

fabrics/fracturesthickness

effective stress

permeabilitydiffusivity

Reservoir exploration and

development

TOCPorosity

gas in place

gas in place deliverability

fabrics/fractures

effective stress

permeabilitydiffusivity


development

TOCPorosity

thickness

gas in place


Outline

Factors Governing OOIP & GIP in Shale

• Area

• Thickness

• Pressure

• Temperature

• Porosity

• Gas Saturation

• Area

• Thickness

• Pressure

• Temperature

• Total Organic

Content

• Maturity

Free Gas in Pores

and FracturesAdsorbed Gas

Total Gas = Free Gas + Adsorbed Gas+

Solution Gas

Solution Gas

• Area

• Thickness

• Pressure

• Temperature

• Total Bitumen/

Liptinite content

• Maturity

BACKGROUND

OGIP Workflow• Isopach Net and Gross Pay

• Frac barriers

• Structure Map

• Vertical Depth

• Temperature Gradient

• Pore pressure Gradient

• Bulk density

Adsorbed

Gas

Free

Gas +

Liquids

Solutio

n

Gas

Adsorption

Isotherms on

samples of

varying TOC

Measurement

TOC on

representative

samples

Calibration

well logs

to TOC

Interpolation

adsorbed gas

through pay

interval via

calibrated logs

Measurement

of pore

compressibility

Measurement

total porosity,

Sw, So

representative

samples

Calibration

porosity, Sw

and So to

well logs

Interpolation

free gas + HC

liquids in

net pay via

calibrated logs

Measurement

or calculation

gas solubility

reservoir P & T

& salinity

Measurement

total

mobile water

Interpolation

of solution gas

through pay

interval via

calibrated logs

Calibration

porosity, Sw

and So to

well logs

TOTAL OGIP = adsorbed + free + solution gas + liquid HCs

Gas

Compositio

n

Canister Desorption

gas sampling f(t)Gas Chromatography± isotopic analyses

Accessible OGIP = Total OGIP/m3 ∙ Stimulated Reservoir Volume

sample basedlog based

• type curves are decline curves that are anticipated to (or do) reflect the

production profile of a well with a particular completion (ie lateral

length, number of stages etc.) and represents the P50 case

• at exploratory stage type curves of what are considered to be

analogous reservoir are used– with early production IPs are

manipulated and later ‘b’

• typically operational changes and more stages result in higher IPs with

typcally similar curve shapes

Applying Type Curves

number of stages

EnCana, 2009 IP

fabrics/fractures

effective stress

permeabilitydiffusion


development

TOCPorosity

thickness

gas in place


whether a rock is currently fractured and its ability tobe fractured are dependent on mechanical properties–which vary with mineralogy, fabric and diagenesis andhence stratigraphy

goal is to develop a geomechanical model of thepotential reservoir to assist in drilling, completions,and development

Geomechanics- Rock Mechanics

the future is mechanical stratigraphy

required for:• predicting orientation of frac (SRV)• density, width and orientation of natural fractures • optimal direction for horizontal wells– for stability

and for intersecting fractures that are open• borehole stability• change in reservoir permeability during production

requires knowledge of:

• in situ stress orientation and magnitude

• pore pressure

• pre existing rock fabric and moduli

• thermal and chemical state of reservoir and fluid

system

0

00

0

• appears most thermogenic gas and oil shales have FEW pre-

existing fractures or those that exist are healed

• object then is to shatter the rock during fracing to increase the

surface area available for drainage

• maximize the stimulated reservoir volume

• not to connect to a pre-existing fracture network

• many shales do not have a pre-existing k network

0

00

0

• appears most thermogenic gas shales have FEW pre-existing

fractures or those that exist are healed

• object then is to shatter the rock during fracing to increase the

surface area available for drainage

• maximize the stimulated reservoir volume

• not to connect to a pre-existing fracture network

• many shales do not have a pre-existing k network

0

20

40

60

80

100

0 20 40 60 80 100 120 140 160

Effective Normal Stress (Residual), s , MPa

Sh

era

Str

ess

,t,

MP

a

Mohr's circle at 14 MPa Mohr's circle 31 MPa Coulomb failure Envelope

Friction Angle = 44.19°

Linear Cohesion = 7 MPa

Stimulated Rock Volume (SRV) and shape of

SRV is a function of the in situ stress field,

mechanical properties of the rocks and frac

design and execution

Mayerhofer et al SPE 102103

Strong correlation between SRV

and production (excellent

correlation between number of

stages at IP)

σHmin=σHmax

σHmin>>σHmax

SRV estimated from microseismic

SRV function of completion

completion function of in situ

stress, rock properties and design

and implementation of frac

a farming operation- you don't frac it you

don't get the gas

http://www.ashdown.org.uk/spps/images/Carol_Talbot/BA2008_CarTal_Tractor%20ploughing%20field.j

pg

high density horizontal well pad

designed to ‘harvest gas’

Diffusion/

Mass

Flow

Matrix

Block

Darcy Flow

Coals- fracture (cleat)

spacing is so low that

matrix perm/diffusion is

not considered rate

limiting

Shales- fracture spacing

is commonly >5 cm and

matrix perm/diffusion

may be rate limiting

Geomechanics and

Permeability/Diffusion Rate

Permeability/Diffusion

• reservoir perm requires well tests

• matrix perm/diff can be measured in

lab

Diffusion/

Advection

5 nm

Desorption

controlling variables

fracture permeability

fracture fabric

effective stress

rock mechanics

matrix permeability/

diffusion

induced during fracs

existing fabric

depth

far field stress

moduli

mineralogyfabric

mineralog

yfabri

ceffective

stressrock

mechanicsgas

composition

deliverabilitypressure/temperature/fluid properties

fracture spacing

Integrated Optimization Process

Quirk, 2010

Integration Optimization

Process• 1. It helps answer the questions…How many

fracs do I need in my horizontal wellbore? How

big should my fracs be?

• 2. It integrates many types of data into one

reservoir package, maximizing value for your

information.

• 3. It provides a way to model fractures in the

complex fracturing we find in shale gas

reservoirs (i.e. Horn River/Barnett).

• The process can be used in any reservoir.

Quirk, 2010

Information that Collecting a Microseismic Dataset

Provides

• Fracture Azimuth

• Fracture Length

• Fracture Height

• Fracture Complexity

• Calculation of Stimulated Reservoir Volume

• Evaluation of the effectiveness of the

completion system

• Calibrated Fracture Modeling and Integration

of Microseismic into a Reservoir Simulator

Quirk, 2010

Trican fracing shale well in north eastern British Columbia

Horn River Basin

• 11 mapped slickwater stages

• Generally complex fracturing

• Long fracture half lengths

• NE-SW fracture azimuth

• Stimulated Reservoir Volume

(SRV) is crucial to production

– Portions of the horizontal are

under-stimulated

Apache Website

Horn River Basin from

http://www.apachecorp.com/Resources/Upload/PrevArticleFiles/files/

Apache_2008_Analyst_Review_08_Canada.pdf

Conclusions

• Low permeability reservoirs require large SRVs with

small fracture spacing and adequate frac conductivity

• Important to understand parameters in the reservoir that

will create complexity so fracture spacing in the SRV can

be understood

• Engineering measures to increase SRV and frac spacing

– Length and orientation of horizontal well

– Treatment size

– Number of stages, number of perf clusters

– More stages and clusters in a cased/cemented completion

increased likelihood of dense fracturing

– Zipper fracs, Simul-fracs

developing a strategy, ranking

prospects.....where do you start?vast resources of gas in tight rock either sorbed or free state– how do you explore?

screens:

1. thickness

2. lateral extent

3. toc

4. maturity

5. mineralogy

6. reservoir accessibility

7. rock mechanics

8. frac barriers

9. fluid sensitivity

10. reservoir pressure

11. cost

12. Poisson’s Ratio

13. Mud logs./shows

need to know at start if

there is enough gas in

place to warrant the cost

of exploring and

completion– what is the

size of the prize)

development risk

max. SRV; optimization of

drilling and completions

Attributes

Lithology fine grained, will indurated

Thickness > 40 m

Current TOC >1% (min. not known)

Effective Porosity to Gas >2.5%

Young Modulus > 4 mmpsia

Poisson's Ratio <0.25

Clay Content <30% (no water sensitive clay)

Pressure Gradient >.5 psi/foot

Mud Log Gas relative but evidence of gas

Gas Shale Target Parameters

Desired

Matrix

porosity

Matrix

Perm.Maturity In Situ

StressPressure E ν

PROSPECT WINDOW

Dep

th\D

iag

en

esis

Rock Mechanics

summary

Matrix

porosity

Matrix

Perm.

Total

Gas

Rock

Mechanics/Fractures

PROSPECT WINDOW

Dep

th\D

iag

en

esis

optimum zone

trade off between

many variables and

will be shale

specific

summary

gas shale primer - east west petroleum€¦ · gas and oil producing shale and nonconventional oil...

Documents