Exposing formation to Hydraulic Pressure Technology Advancement for Horseshoe Canyon CBM Stimulation

Francois Cantaloube– Schlumberger Original Presentation by: Francois Cantaloube – Schlumberger Mike Yu – EnCana Corporation.

CSUG – Nov 2008.

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 Reservoir conditions require High N2 pump rates for an optimized stimulation Operational constraints limit high pumping rates

Effective Pressure at the Coal Face Efficiency loss in the system N2 Pumping rate @ 1200 scm / min

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

Changing The Game The inefficiency of the current approach has triggered the need to optimize the process of CBM stimulation 9 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)

Effective pressure at the coal face 100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 2 5/8" CT 2 7/8" CT 3 1/4" CT ThorFRAC N2 Pumping rate @ 1200 scm / min Frictional losses Pressure at coal face

High-Energy Release at Coalface (ThorFRAC) 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

Bottom-Hole Dynamics Tr Press Ann Press i-BHP i-BHT N2 Rate 60.0

50.0

40.0

Pressure loss in the system 30.0

20.0

10.0

0.0

10:43:41 10:44:24 10:45:07 10:45:50 10:46:34 600 400 200 10:47:17 10:48:00 10:48:43 10:49:26 10:50:10 0 10:50:53 1600 1400 1200 1000 800

Bottom-hole Dynamics

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

“Wet” Section

South Areas

Statistical Analysis Completion by Pad Belly River Completed

BLRV Contribution Poor gas production due to Wet Section

Statistical Analysis 40% Improvement

Field Production Comparison

Flow contribution post Conventional N2 Fracturing

24

Flow contribution post Conventional ThorFRAC Fracturing

25

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

CONTACT Reservoir Increase production rates Maximize Reserves Effective stimulation 27