The production of methane from wet coalbeds is often associated with the production of significant amounts of water. While producing water is necessary to desorb the methane from the coal, the damage from the drilling fluids used is difficult to assess, because the gas production follows weeks to months after the well is drilled. Commonly asked questions include the following:• What are the important parameters for drilling an organic reservoir rock that is both the source and the trap for the methane?• Has the drilling fluid affected the gas production?• Are the cleats plugged? • Does the "filtercake" have an impact on the flow of water and gas?• Are stimulation techniques compatible with the drilling fluids used?This paper describes the development of a unique drilling fluid to drill coalbed methane wells with a special emphasis on horizontal applications. The fluid design incorporates products to match the delicate surface chemistry on the coal, a matting system to provide both borehole stability and minimize fluid losses to the cleats, and a breaker method of removing the matting system once drilling is completed. This paper also discusses how coal geology impacts drilling planning, drilling practices, the choice of drilling fluid, and completion/stimulation techniques for Upper Cretaceous Mannville-type coals drilled within the Western Canadian Sedimentary Basin. A focus on horizontal coalbed methane (CBM) wells is presented.Field results from three horizontal wells are discussed, two of which were drilled with the new drilling fluid system. The wells demonstrated exceptional stability in coal for lengths to 1000 m, controlled drilling rates and ease of running slotted liners. Methods for, and results of, placing the breaker in the horizontal wells are covered in depth.
TX 75083-3836, U.S.A., fax 1.972.952.9435. AbstractThe production of methane from wet coalbeds is often associated with the production of significant amounts of water. While producing water is necessary in order to desorb the methane from the coal itself, the damage from the drilling fluids used is difficult to assess because the gas production follows weeks to months after the well is drilled. Commonly asked questions include: What are the important parameters for drilling an organic reservoir rock that is both the source and the trap for the methane? Has the drilling fluid affected the gas production? Are the cleats plugged? Does the "filtercake" have an impact on the flow of water and gas? Are stimulation techniques compatible with the drilling fluids used?This paper describes the development of a unique drilling fluid to drill coalbed methane wells, with a special emphasis on horizontal applications. The fluid design incorporates products to match the delicate surface chemistry on the coal, a matting system to provide both borehole stability and minimize fluid losses to the cleats, and a BREAKER method of removing the matting system once drilling is completed.Field results from three horizontal wells will be discussed, two of which were drilled with the new drilling fluid system. The wells have demonstrated exceptional stability in coal for lengths to 1000 m, controlled drilling rates and ease of running slotted liners. Methods for, and results of, placing the BREAKER in the horizontal wells are covered in depth.
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.
TX 75083-3836, U.S.A., fax 1.972.952.9435. AbstractThe production of methane from wet coalbeds is often associated with the production of significant amounts of water. While producing water is necessary in order to desorb the methane from the coal itself, the damage from the drilling fluids used is difficult to assess because the gas production follows weeks to months after the well is drilled. Commonly asked questions include: What are the important parameters for drilling an organic reservoir rock that is both the source and the trap for the methane? Has the drilling fluid affected the gas production? Are the cleats plugged? Does the "filtercake" have an impact on the flow of water and gas? Are stimulation techniques compatible with the drilling fluids used?This paper describes the development of a unique drilling fluid to drill coalbed methane wells, with a special emphasis on horizontal applications. The fluid design incorporates products to match the delicate surface chemistry on the coal, a matting system to provide both borehole stability and minimize fluid losses to the cleats, and a BREAKER method of removing the matting system once drilling is completed.Field results from three horizontal wells will be discussed, two of which were drilled with the new drilling fluid system. The wells have demonstrated exceptional stability in coal for lengths to 1000 m, controlled drilling rates and ease of running slotted liners. Methods for, and results of, placing the BREAKER in the horizontal wells are covered in depth.
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