“We saw immediate improvement in the quality of our solids control. MONGOOSE PT shaker performance easily justified replacing the remaining shakers; combined performance reduced our waste disposal costs by more than 40%. Moreover, our mud costs were reduced by more than 25%.

The Situation
The operator was drilling a steam assisted gravity drainage (SAGD) program in Canada’s Athabasca Tar Sands using
M-I SWACO SAGDRIL* fluid. These wells are shallow, extended-reach horizontal wells (< 500 m true vertical depth, ~1500 m measured depth) drilled through fine-grained unconsolidated sands laden with highly viscous bitumen. Typical drilling parameters include large-diameter wellbores (up to 375 mm (141⁄4-in.) Intermediate/build, 270 mm (105⁄8-in.) Main/lateral), high penetration rates (40 to 50 m/hr [130 to 165 ft/hr]) and high pump rates (2.5 to 3.0 m3/min [660 to 790 gal/min]). The shakers and screens have to not only handle extreme solids loading, but also are subjected to a viscous, sticky tar that readily coats and plugs the screen mesh.

The rig was equipped with competitor high G-force linear motion shale shakers on the Primary complex and two shakers on the Secondary complex. M-I SWACO personnel were requested to perform a shaker evaluation that included analysis with its patented VSA* software. This analysis indicated that the shakers on the rig were not performing at an acceptable level. G-forces were lower than expected and there was an unacceptable amount of solids by-passing the shakers, accumulating in the mud tanks, and contaminating the SAGDRIL fluid.

Normal drilling operations using the original shaker configuration were plagued by a number of problems, including:

  • Continual tar accretion causing excessive screen blinding
  • Excessively wet cuttings
  • Increased mud dilution and subsequent increased cost caused by high surface losses
  • Excessive drilling waste
  • Poor screen life caused by high solids loading

The Solution
M-I SWACO initially replaced the two competitor shakers on the Secondary complex with two MONGOOSE PT Dual Motion shakers. These shakers showed immediate improvement in fluid handling and solids capacity. Screens were upgraded from 84 mesh (generic screens) to 110 XR* and 150 XR Mesh on the MONGOOSE PT shakers. The cuttings were noticeably dryer; one shaker was able to handle the full fluid flow of 2.5 m3/min (660 gal/min).

Once the operator identified how efficiently the MONGOOSE PT shakers functioned, he ordered two more to replace the other three competitor shakers on the Primary complex.

The Results
Installation of the M-I SWACO MONGOOSE PT Dual Motion shakers immediately improved overall solids-control efficiency and had a significant impact on the project cost. Drilling fluid costs were substantially reduced by as much as 25% while waste disposal volumes and costs were also reduced by as much as 40%. This helped reduce the final project costs to approximately 25% below estimates. The improved shaker with its unique dual motion capability and shaker screen performance also resulted in a marked decrease in screen blinding caused by bitumen accretion. The improved shaker screen life also freed up at least one crew member who had previously been tasked with shaker screen maintenance, reducing personal exposure to the drilling fluid and improving the HSE situation.

Summary
M-I SWACO MONGOOSE PT Dual Motion shakers outperformed the original competitor high G-force shale shakers by a significant margin, resulting in increased performance and reduced cost. The customer was “extremely satisfied” with the results.

By M-I SWACO Operator Senior Drilling Engineer

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