SHALE PETROPHYSICAL CHARACTERISTICS

Kashy AminianPetroleum & Natural Gas EngineeringWest Virginia University

INFUSEFebruary 29, 2016

KEY RESERVOIR CHARACTERISTICS

Porosity

Permeability

The Reservoir Rock Contains a 3-D Network ofInterconnected Pores which allows for toStorage and Transmission of Fluids.

KEY RESERVOIR CHARACTERISTICS

THE OPEN SPACE CREATED BETWEENGRAINS DURING DEPOSITION IS REFERREDTO AS THE VOID, OR PORE, SPACE.

( )

p

b

b

p

V V

V Bulk Volume

V Pore Void Volume

φ =

=

=

KEY RESERVOIR CHARACTERISTICSPERMEABILITY IS DEFINED BASED ON AN EQUATION, DEVELOPEDBY HENRY DARCY:

( )1 2

q LkA p p

µ=

−

.

q Flow Rate through the Porous MediumA The Area across whic

Fluid Viscosith the flow occurs

L Length of the Mediumyµ

==

==

KEY RESERVOIR CHARACTERISTICS

( )1 2

kq LA p p

µ−

=

1 cp1 cc/sec

1 cm2

1 cm

1 darcy

1 atmOne darcy is a relatively high permeability and millidarcy(md) is commonly used as the permeability unit.

1 darcy = 1000 md

PERMEABILITY MEASUREMENT

Low Pressure High PressureGAS SLIPPAGE

UNCONVENTIONAL RESERVOIRS

SHALE GAS RESERVOIRS

GAS

STO

RAG

ECA

PACI

TY

PRESSURE

LANGMUIR ISOTHERM

=+L

SL

V pG

P pGs = Gas Storage CapacityVL = Langmuir Volume ConstantPL =Langmuir Pressure Constantp = Pressure, psia

MEASUREMENT OFSHALE PETROPHYSICAL PROPERTIES

PORE VOLUME

ADSORPTION

• Low-pressure gas pycnometry

• High-pressure mercury injection

• Low-temperature adsorption

• Gravimetric• Volumetric

• GRI Method• Pressure Pulse Decay

PERMEABILITY

PORE SIZE DISTRIBUTION• MICP• NMR• SEM/STEM• Low-temperature Adsorption

SHALE PERMEABILITY MEASUREMENT

• IT IS NOT PRACTICAL TO MEASURE THE PERMEABILITY OFSHALE BY CONVENTIONAL (STEADY-STATE) TECHNIQUESBECAUSE OF LOW PERMEABILITY.

• UNSTEADY-STATE METHODS

GRI METHOD (CRUSHED SAMPLE)

PRESSURE PULSE DECAY

CRUSHED SAMPLE PERMEABILITYDEVELOPED BY GAS RESEARCH INSTITUTE AND IS REFERRED TO AS "GRI" METHOD.

Particles in the 20-35 US mesh size range (0.85 to 0.5mm)

No Standard Protocol

Inconsistent Results

PRESSURE PLUS DECAY

DIFFERENT INTERPRETATIONS

COMPLEX AND TEDIOUS CALCULATIONS

CHALLENGES

• GAS SLIPPAGE CORRECTION

• IMPACT OF GAS ADSORPTION

• IMPACT OF STRESS

PRECISION PETROPHYSICAL

ANALYSIS LABORATORY (PPAL) AT WVU

MEASUREMENT CAPABILITIES

• PERMEABILITY (NANO-DARCY RANGE).• PORE VOLUME (0.1% ACCURACY).• ABSOLUTE PERMEABILITY (GAS PRESSURE CORRECTION)• IMPACT OF STRESS (RESERVOIR CONDITIONS).• IMPACT OF ADSORPTION

• PORE STRUCTURE CHARACTERIZATION

ACCURATE, CONSISTENT, AND REPEATABLE RESULTS

ABSOLUTE PERMEABILITY

Traditional Klinkenberg AnalysisGas Slippage Modified Klinkenberg Analysis

Gas Double Slippage

y = 90090x - 66.106R² = 0.9865

y = 57377x + 11.06R² = 0.9992

0

200

400

600

800

1000

0.0E+00 2.0E-03 4.0E-03 6.0E-03 8.0E-03 1.0E-02

Perm

eabi

lity,

nD

Inverse of Pressure, Psia-1

Helium

Nitrogen y = 8E+06x + 154.3R² = 0.9603

y = 5E+06x + 155.51R² = 0.9705

0

200

400

600

800

1000

0.0E+00 2.0E-05 4.0E-05 6.0E-05 8.0E-05 1.0E-04

Perm

eabi

lity,

nD

Inverse of Pressure Squared, Psia-2

ADSORPTION

ADSORPTION ISOTHERM

0

10

20

30

40

50

60

70

0 1000 2000 3000

Gs,

SFC

/ton

Pressure, psia

104 °F, TOC: 1.2% (Published Data)

79 °F, TOC: 0.8% (PPAL)

Crushed Sample (Commercial Lab)169 °F, TOC: 0.8%

IMPACT OF STRESS

( )1 3ok k

( )oln p p

SEQUENTIAL STRESS

90

110

130

150

170

190

210

230

250

500 2500 4500 6500 8500

Perm

eabi

lity,

nD

Net Stress, Psia

Series1Series2

90

140

190

240

290

340

500 2500 4500 6500 8500

Perm

eabi

lity,

nD

Net Stress, Psia

Series1Series2

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5

Series1Series2Series 4

( )oln p p

ADSORPTION ISOTHERMS

Multilayer Adsorption

Slit-like poresNitrogen Adsorption at Low Temperature

Micromeritics ASAP 2020