Technology of Production from Shale - Fossil Fuel … · Permeability §Require Hydraulic ......

European Unconventional Resources

Technology of Production from Shale

Doug Bentley, European Unconventional, Schlumberger

May 29th, 2012Johannesburg, South Africa


What are Unconventional Reservoirs

– Shale both Gas & Oil– Coal Bed Methane - CBM– Tight Gas– Gas Hydrates


§ Organic Rich Shale§ Source Rocks§ Surrounding poor quality rock

ignored as non economic in the past.§ Porosity sources are mostly

unconventional§ Matrix Rock has Very Low

Permeability§ Require Hydraulic Stimulation to

make productive

What are Shale Reservoirs


Shale Exploration - Starting Point

Petroleum Systems Modeling

Mosca et al. (2010) 3D Petroleum Systems modeling applied to unconventional shale gas play: prediction of sweet spots based on areal and depth distribution of sorption capacity in shale gas. Abstract AAPG Annual Convention and Exhibition, New Orleans, April, 2010.

Devon Energy have used Petroleum Systems Modeling to build their acreage position in a North American shale gas play:

•“Modeled variability of the gas adsorption and saturation thresholds as a function of temperature, maturity, and kinetic scheme through space and time by means of a 3D numerical simulation of hydrocarbon generation and expulsion”

•“Based on these results it was possible to select sweet spot locations to be leased for this project, consequently minimizing the lease and exploration costs”


Reservoir Quality§ Maturity§ Organic Content§ Porosity§ Permeability§ Water Saturation§ Pressure§ Gas in Place

Completion Quality§ Stress Anisotropy § Fracture Containment§ Near & Far Field Stress§ Clay Content & Type§ Fabric Pattern§ Mineral Sensitivity§ Wellbore Placement

Understanding Reservoir & Completion Quality


Shale Gas Reservoir Quality - Maturity Control – Petrology Tectonic subsidence (burial depth timing)Diagenesis (cements, clay, organics)

European Unconventional Resources7

Shale Gas Reservoir Quality – Organic Content & Porosity

Conventional sandstone

700 µm Pore system

Mineral framework Gas shale

100 µmFree gas in pore space Free gas in pore space

Adsorbed gas on kerogen

Kerogen

European Unconventional Resources0 6000 8000 10000

0

200

400

600

800

1000

0

200000

400000

600000

800000

1E+006

1.2E+006

1.4E+006

1.6E+006

1.8E+006

2E+006

Cumulative Time

Wel

l GA

S P

rodu

ctio

n R

ate,

Msc

f/d

Wel

l GA

S C

umul

ativ

eP

rodu

ctio

n, M

scf

Km = 0.0001 md

Km = 0.0005 md

Shale Gas Reservoir Quality – Permeability


R² = 0.7254

0

100

200

300

400

500

600

0 10 20 30 40 50 60

Perm

(nD)

Sw

Shale Gas Reservoir Quality – Saturation


Shale Gas Reservoir – Parameter RangesA-R Bulk Density

A-R Grain Density

Dry Grain Density Porosity Water

SaturationGas

SaturationMobile Oil Saturation

Gas-Filled

Porosity

Bound Hydrocarbon

Saturation

Bound Clay

Water

Pressure Decay Perm

TOC

(g/cm3) (g/cm3) (g/cm3) (% of BV) (% of PV) (% of PV) (% of PV) (% of BV) (% of BV) (% of BV) (md) (wt %)1 2.48 2.622 2.645 6.65 15.16 81.4 3.43 5.42 0.5 6.21 0.00027 3.772 2.436 2.559 2.584 6.26 18.5 76.44 5.05 4.79 1.29 7.03 0.00023 6.753 2.48 2.633 2.652 6.87 15.43 83.9 0.66 5.77 0.5 6.8 0.00027 3.364 2.327 2.487 2.509 7.74 13.09 83.02 3.87 6.43 0.73 6.67 0.000347 7.415 2.373 2.539 2.558 7.58 11.17 85.92 2.9 6.52 0.34 2.63 0.000359 5.956 2.461 2.605 2.63 6.87 16.26 80.42 3.32 5.53 0.99 7.19 0.000298 5.047 2.75 2.812 2.818 2.48 7.41 88.89 3.69 2.21 0.29 1.87 0.000044 0.988 2.341 2.511 2.527 7.66 7.67 88.39 3.93 6.77 0.82 4.9 0.000463 7.849 2.428 2.573 2.599 7.11 17.77 79.06 3.16 5.62 0.75 7.01 0.000292 4.12

10 2.468 2.633 2.645 6.87 5.5 91.15 3.34 6.26 0.91 4.58 0.000305 4.0211 2.525 2.593 2.661 6.53 54.54 40.42 5.03 2.64 0.1 5.19 0.000112 2.2912 2.637 2.73 2.765 5.27 34.63 64.44 0.92 3.4 0.05 5.04 0.000149 613 2.451 2.543 2.599 6.97 47.77 51.58 0.64 3.6 0.28 9.45 0.000161 5.314 2.432 2.574 2.605 7.29 24.19 75.19 0.61 5.48 0.28 7.48 0.000333 5.7315 2.436 2.56 2.579 5.96 18.23 81.01 0.75 4.83 0.28 5.05 0.000346 6.5916 2.445 2.548 2.573 5.38 9.65 75.13 15.21 4.05 0.4 3.12 0.000243 5.1917 2.523 2.619 2.687 7.02 9.07 51.88 39.04 3.65 0.67 3.22 0.000176 5.6818 2.472 2.606 2.621 5.99 13.06 85.56 1.37 5.13 0.25 4.76 0.000325 6.26

Sample No

�Saturations: Sliquid < 45%�Permeability: > 100 nD� TOC: > 2 wt%

�Effective phi: 4 to ~12 pu


Shale Gas Reservoir – Pressure Measurement

Pumpout module

Packer

Wireline

Packer

Pressure gage

Flow control module

Sliding coupling

P

P

Inflate seal valve

Interval seal valve 1m

Sample chamber

P

3ft

0 60.0 120.0 180.0 240.0 300.0 360.0 420.0 480.0 540.0 600.00

1000

2000

3000

4000

5000

6000

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50Interval Pressure (psi)

Packer Pressure (psi)

Injection Rate (gal/min)

Time, min

Pres

sure

, psi R

ate, gpm


Shale Gas Reservoir – Pressure MeasurementEight Hour Shut-in

35 psi

§ Run Sensitivity during Closure§ Estimate pressure at 0.453 psi/ft§ Gradient used to estimate Gas in

Place, assuming Saturated System


Shale Gas Reservoir – Gas in Place

0

20

40

60

80

100

120

140

0 200 400 600 800 1,000 1,200Pressure, psia

Adso

rbed

Gas

Con

tent

, scf

/ton

Total Organic Carbon= 16 %

14 %

12 %

10 %

8 %

6 %

4 %

Methane Adsorption Isotherms(as a function of Total Organic Carbon)

§ Gas in Place Calculated from CBM Standard BCF per Sq Mile§ TOC is considered Saturated for

most cases as we are well over 1000 psi in most wells.§ Effective porosity is used with

estimated pore pressure.§ Gas in Place is Integrated over total

Shale bottom to top of interval.§ Examples:§ Core Barnett 139 BCF/ Sq Mile§ Marcellus 60 BCF/Sq Mile§ Haynesville 129 BCF/Sq Mile


ECS / XRDRHOBRHOM

SwPorosity

TOCPermPorosity

GIPGas-PhiELANResistivityGR

Shale Gas – Core Calibrated Reservoir Quality


Shale Gas Completion Quality – Mechanical Properties Shale can be very anisotropic due to laminations and bedding(especially expandable clays or organic)§ TIV – Transverse Isotropic with Vertical axis of

symmetry

Shale, laminated sands

Comp.VerticalVelocity

Comp.HorizontalVelocity

Not the Same!!


Shale Gas Completion Quality – Anisotropic Properties

16

FastStrong

Slow Weak


Shale Gas Completion Quality – Anisotropic Stress

Argillaceous Shale BedEh = 6 x 106 psiEv = 3 x 106 psi

νh = 0.26νv = 0.25

Overburden

Siliceous Shale Bed Eh = 8 x 106 psiEv = 6 x 106 psi

νh = 0.16νv = 0.13

Argillaceous Shale:Isotropic: σh = 0.66 psi/ft Anisotropic: σh = 0.87 psi/ft

Siliceous Shale:Isotropic: σh = 0.53 psi/ftAnisotropic: σh = 0.57 psi/ft

Anisotropic shale properties increases stress in argillaceous intervals


Shale Gas Completion Quality – Fracture Containment Mineralogy

Closure StressφD & φNRes.GR

Isotropic & Anisotropic

Closure Stress

Swelling Clays = High Closure Stress

High Silica Volume = Low Closure Stress

Carbonates my be High or Low Closure Stress

High Clay Volume = High Closure Stress


Shale Gas Completion Quality – Clay Volume

- Good relationship between theclay volume and the differencebetween the Anisotropic andIsotropic closure stress models

- Correlation is weakest at lowclay volumes where therocks are more isotropic

- Increasing the clay volumeincreases the error in theisotropic stress model

Tota

l Clay

Vol

ume

Difference in Anisotropic and Isotropic Stresses


Shale Gas Completion Quality – Clay Type

- Excellent relationship betweenthe volume of swelling clay and the difference between theAnisotropic and Isotropicclosure stress models

- Small amounts of swellingclays dramatically increaseclosure stress

- Not captured withIsotropic models

Swell

ing

Clay

Vol

ume

Difference in Anisotropic and Isotropic Stresses


Shale Gas Completion Quality – Role of Fabric• Rock fabric can be very complex • Fractures can be open, healed, drilling induced or reactivated• Clay is usually found in layers• Mud systems need to limit activation of healed systems• All planes of weakness need to be mapped• Regional stress needs to be understood


Shale Gas Completion Quality – Creating Surface Area

Complex Hydraulic Fracture Simulations

3D Stress Mapping

Creating Productive Surface Area


Shale Gas Completion Quality – Maintaining Surface Area 20/40 Resin Coated Sand Argillaceous Facies

20/40 Sand Siliceous Facies

Post-Conductivity Testing Fracture Face Image


Shale Gas Completion Quality – Maintaining Surface Area Results of Channel Fracturing•Reductions in water of 25% and proppant of 42% •Production: 20-50% increase

•Proppant placement rate: 99.96%

Key elements• Improved fracture clean-up

• Low risk of screenout

• Longer effective fracture half-lengths


Shale Gas Completion Quality – Well Placement 4100

4200

4300

4400

4500

4600

47003000 3500 4000 4500

TVD

- ft

Stress - ps i

-0.10 -0.05 0.00 0.05 0.10

Width at Wellbore - in @115.4 min

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Fracture Half Length - f t @115.4 min

Frac Half Length Propped Frac Half Length4100

4200

4300

4400

4500

4600

47003000 3500 4000 4500

TVD

- ft

Stress - ps i

-0.10 -0.05 0.00 0.05 0.10


0 200 400 600 800 1000 1200 1400 1600 1800 2000


Frac Half Length Propped Frac Half Length4100

4200

4300

4400

4500

4600

47003000 3500 4000 4500

TVD

- ft

Stress - ps i

-0.10 -0.05 0.00 0.05 0.10


0 200 400 600 800 1000 1200 1400 1600 1800 2000


Frac Half Length Propped Frac Half Length

Upper Shale

Lower Shale

Lower Boundary

Argillaceous Lower Shale


Shale is heterogeneous at all scalesReservoir Quality and Completion Quality can be defined.Data integration is used to define and exploit the reservoir.Production improvements come from many things

• Well placement where conductivity to the developed fracture system can be developed and maintained.• Large surface area contained in the reservoir.• Propprant concentrations placed to maintain surface area and minimize pinch points in the reservoir.• Water flowback program to minimize reservoir damage and fines production.• Stimulation fluids program to limit Chemo-mechanical weathering.

Reservoir & Completion Quality - Summary

Technology of Production from Shale - Fossil Fuel … · Permeability §Require Hydraulic ......

Documents

Transcript of Technology of Production from Shale - Fossil Fuel … · Permeability §Require Hydraulic ......