Development and Field Results of a Unique Drilling Fluid Designed for Heavy Oil Sands Drilling

Abstract

Drilling Heavy Oil Sands are traditionally fraught with many technical challenges. Stability of the wellbore, accretion of the tar on drill string and solids control equipment, torque-drag considerations, extreme temperature conditions, as well as the disposal of oily solids are just some of the challenges that need to be met. This paper describes the development and large project field success of a new drilling fluid designed to meet these challenges. The water-based fluid is based upon two guiding principles, the ability to incorporate the bitumen into the mud itself, and the capability to later break the bitumen from the mud system. Incorporation of the bitumen into the Heavy Oil Sands Mud (HOSM) is via a direct emulsification and results in zero accretion, virtually oil-free sand from the solids control equipment, fast drilling rates and good hole stability. Data from a 156 well (78 pair) horizontal Steam Assisted Gravity Drainage (SAGD) heavy oil program in Northeastern Alberta shows the robustness and effectiveness of the system. The new oil in water direct emulsion system drilled on average 1000 meter average horizontal wells in 6.1 days per (Injector/Producer) well pair. Lost time due to wellbore instability or accretion problems was virtually eliminated. Total project costs were 20% under budget, and the entire 156 wells were finished 5 months ahead of the drilling curve.

Laminar Bingham fluid flow between vertical parallel plates

“…This problem occurs because of too much heat being transferred from the production tubing to the surrounding casings. Gas hydrate, paraffin and asphaltene precipitation are the result of cooling the production fluid below critical temperatures, and these can lead to plugging of the well production conduit [1]. This problem also occurs because of too much heat being lost to the surroundings.…”