Exposing formation to Hydraulic Pressure-

Technology Advancement for Horseshoe Canyon CBM

Stimulation

Original Presentation by:Francois Cantaloube – SchlumbergerMike Yu – EnCana Corporation.CSUG – Nov 2008.

Francois Cantaloube– Schlumberger

Agenda

The Conventional Approach

The ThorFRAC Approach

Bottom-Hole Dynamics

Tool Capabilities

Case History and Results

The Conventional Approach

Coal Cleat Matrix ─ Natural path of least resistance

Preferential damage path Complex stimulation requirements

─ Low Young’s modulus

Stimulation fluid─ Low effective viscosity of N2─ Compressibility

Equipment limitation at surface─ Inefficiency due to friction

losses─ Bigger footprint─ Higher costs

Operational constraints limit high pumping rates

Reservoir conditions require High N2 pump rates for an optimized stimulation

Effective Pressure at the Coal Face

N2 Pumping rate @ 1200 scm / min

Efficiency loss in the system

Mechanisms at Coalface

Pressurizing BH

N2 leak-off into formation as BH is pressurized prior to break down

Mechanisms at Coalface

Break down

Mechanisms at Coalface

Remaining volume injection

Limitations on Current Practices

Significant fracture propagation is not likely to occur with low viscosity (N2)

Experimental approaches have shown that ultra high-rates deliver better stimulation results than high-volumes

Current “high pumping rates” are limited by friction losses

CBM economics limit major operational cost increases

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The inefficiency of the current approach has triggered the need to optimize the process of CBM stimulation

Develop a Multi-zone/high-rate system that effectively transfers energy/pressure to the formation*, optimizing the volume of N2 used.

* Patented process (#2 550 750)

Changing The Game

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2 5/8" CT 2 7/8" CT 3 1/4" CT ThorFRAC

Frictional losses

Pressure at coal face

Effective pressure at the coal face

N2 Pumping rate @ 1200 scm / min

Pressurizing BHA

High-Energy Release at Coalface(ThorFRAC)

Pressurizing BHA

No N2 leak-off into formation as BH is pressurized

N2 Volume optimization

High-Energy Release at Coalface

(ThorFRAC)

Pressure Released at highest rate possible in a N2 CoilFRAC treatment

High-Energy Release at Coalface

(ThorFRAC)

Incremental surface area exposed during subsequent pumping

High-Energy Release at Coalface

(ThorFRAC)

Bottom-Hole Dynamics

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Tr Press Ann Press i-BHP i-BHT N2 Rate

Pressure loss in the system

Bottom-hole Dynamics

Conventional - Pressure builds up as smaller open area is pressurized

ThorFRAC* - Pressure pulse opens up more coal area

Pressure Vs. Time

Conventional - Pressure builds up as smaller open area is pressurized

ThorFRAC* - Pressure pulse opens up more coal area

Pressure Vs. Time

Tool Capabilities

Operation:─ Actuate as many times as required.─ Actuate at any release pressure without POOH.─ Follow-up pumping after pressure release.─ 1 meter minimum interval straddle.

Real Time Depth control (CCL) and BHP & BHT enabled through fiber optics.

Fluids:─ Nitrogen: all current cases.─ Foam: no cases but no apparent restrictions─ Slurry: Will need to determine the effects on tool.

Depth: ~1,000 meters range. Casing: 114.3mm, current. 139.7mm, doable. Pressure Limitation: Tool (49,000 kPa), Cups (35,000 kPa).

Case History

Formation: Horse Shoe Canyon CBM(Belly River formation completed in some wells)

24 wells on six 4-well pads New completions- No re-fracs Perform 2 High Energy Release, and 2 Conventional

treatments per pad

Study Area Locations

Eight-Month Cumulative Production Comparison

North Areas

South Areas

“Wet” Section

Statistical Analysis

Belly River Completed

BLRV Contribution

Poor gas production due to Wet Section

Completion by Pad

Statistical Analysis

40% Improvement

Field Production Comparison

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Flow contribution post Conventional N2 Fracturing

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Flow contribution post Conventional ThorFRAC

Fracturing

Conclusions

Bottom-hole assembly function as per design

Pressure response indicates more surface area was opened

No complication of surface logistics

Horseshoe Canyon CBM production improvement >40%

Spinner logs run on each wells stimulated with the 2 different methods have shown a more consistent production contribution per zone

Full potential of high-energy release system yet to be realized

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CONTACT Reservoir Maximize Reserves

Effective stimulationIncrease production rates