Case Study - FlexFirm™

February 2007

$80,000 savings with FlexFirmTM in Rainbow Lake
FlexFirmTM reduces disposal costs and drills Ft. Simpson shale.

Challenge

Rainbow Lake is well known for its drilling challenges. Previously Husky has utilized various drilling fluid alternatives which included PHPA / Amine combinations, KCL polymer, K2SO4 polymer etc. in an attempt to stabilize the Ft. Simpson and set intermediate casing. The most successful application has been KCL polymer to date.

While it has an admirable inhibitive feature, KCL polymer has far less than acceptable environmental features. Disposal of “enhanced bentonite based fluids” requires an intermediate Microtox toxicity test to evaluate the fluids and drill cuttings prior to any land application. Unfortunately the result of the Microtox test on the KCL fluids and drill cuttings prior to disposal is a fail. This has resulted in exorbitant disposal costs averaging $80,000 for disposal to landfill. Husky’s objective is to find a suitable replacement to drill the intermediate hole containing the Ft. Simpson while meeting the G50 guidelines for disposal of the fluid and drill waste on land to eliminate the extra costs of hauling to landfill.

Recommendation/Plan

Utilize FlexFirmTM – environmentally accepted silicate drilling fluid.

      • Drill 222 mm OH from surface shoe at 361 meters with 1% FlexFirmTM
         water to 950 meters.
      • Mud up with 1% FlexFirmTM polymer from 950 meters to intermediate
         casing point at 1836 meters in the Sharky formation.
      • KOP planned for 950 meters and build angle to 25 degrees through
         the Ft. Simpson shale and hold to intermediate casing depth.
      • Microtox fluid and cuttings to confirm both Pump Off and Mix Bury Cover (MBC).
      • Drill 156 mm OH from intermediate shoe to Total Depth at 1931
         meters with water.

Execution

Drilled out surface shoe with 1% FlexFirmTM water to 950 meters and mudded up
with XC polymer and continued to 1337 meters at an angle of 20 degrees at a ROP
of 14.6 meters / hour.

      • Minor slivers noted from 1200-1400 meters. Unsure of whether it
         was over-pressure causing the slivers or minor shale hydration.
      • Substantial depletion was noticed in the Ft. Simpson shale interval.
      • Drilled to 1776 meters with 1% FlexFirmTM at a ROP of 10.3 meters / hour.
      • Drilled through the Muskeg anhydrite to intermediate casing point at
         1836 meters at an ROP of 2.3 meters / hour. The bit underperformed.
      • Cuttings were segregated on location from fluids. Fluid waste
         was temporarily placed in a remote sump.

Results

The drilling program was on budget. Extra days were spent fishing a test plug in the surface
casing prior to drilling 222 mm intermediate hole. Time was lost drilling with an unsuitable bit in the Muskeg anhydrite.

FlexFirmTM performed very well through the 222 mm intermediate hole. The FlexFirmTM floc water section drilled on budget and the water was maintained clean. FlexFirmTM polymer maintained wellbore stability while drilling directionally. Depletion of FlexFirmTM through the Ft. Simpson shale was noticed as anticipated. There was no noticeable effect of the Muskeg anhydrite on the fluid properties which simplified the potential challenge.

Samples of fluid and cuttings were evaluated throughout the intermediate interval to perform preliminary chemical analysis for Electrical Conductivity (Ec) and Sodium Adsorption Rate (SAR) to evaluate potential disposal alternatives.

Fluid and drill waste remaining from the drilling activities were tested using the Microtox for toxicity and passed. Further chemical analysis resulted in approval for Pump Off of the fluids and Mix Bury Cover (MBC) of the drill waste at a ratio of 3:1.

operator benefits

Husky drilled the intermediate hole directionally through the Ft. Simpson shale with a total of 4 hours of reaming. FlexFirmTM was on budget and demonstrated approximately a 10% reduction in fluid costs compared to KCL polymer. Substantial environmental savings of $80,000 were realized by disposing of all FlexFirmTM waste (fluids & cuttings) on the land
rather than landfill.

Past projects have utilized landfills to dispose of the KCL fluid and cuttings as a result of
failed Microtox tests and unsuitable Mix Bury Cover (MBC) ratios.