Optimization of Milling Plugs With Coil Tubing on the Pinedale Anticline

Abstract

Abstract One main challenge facing the Shell Pinedale Anticline completions is effectively drilling 21 plugs per well throughout a 6500′ hydraulically fractured completion interval (7,500′ – 14,000′ TMD) in a safe, timely, and cost effective manner. Ths process of drilling plugs has improved considerably with respect to time, cost, and environmental impact since drilling and completions operations ramped up in 2002. Early bottom hole assembly (BHA) designs used for the drilling of plugs with coiled tubing (CT) were limited to drilling approximately 4-6 plugs before tripping out of hole for a new mill or motor. In addition to the long cycle times, this BHA design also resulted in high frequency of sticking, disconnects, and costly fishing jobs. Since no advanced flowback equipment or layouts were used on early drill outs, all gas was flared. Improvements to all aspects of the drilling process, such as BHA design and flowback layout, have led to routinely drilling up as many as 21 composite bridge plugs, with one coiled tubing trip, limited flaring of gas, and reduced cycle time of less than 24 hours from rig up to rig down. This paper will focus on four main areas of improvement: 1) Bottom Hole Assembly (BHA) improvements; mill design, motor performance 2) Surface equipment improvements resulting in limited flaring, 3) Composite plug selection, 4) CT selection – taper, grade, size.