Coiled Tubing (CT) cementing has been widely used and highly successful for remedial squeeze and plug back operations for over 20 year's1,2,3 . However, the vast majority of these wells were at deviations less than 90 degrees.
A long horizontal well in the Alpine field on the North Slope of Alaska was drilled early in the development phase and was out of pattern (Fig. 1). The well required a plug back and sidetracking to maintain desired off-take strategy (Fig. 2). The well was drilled to a total depth of 11,984 feet and completed with approximately 2,050 feet of 4-1/2" slotted liner inside the 2,210’ of 6-1/8" hole. Near the middle of the horizontal section, the well's deviation climbed to a maximum of 96 degrees.
Cementing operations have long been recognized as a problem in horizontal wells. However, a search of the SPE online library identified only 5 papers that mentioned the challenge we faced while a search of "horizontal" yielded 5,534 hits. Although the 5 papers did discuss the problem and gave some general guidance to cement design consideration, there was little specific information on the "best practice" approach to Plug and Abandon (P&A) long horizontal wellbores.
Based on the successful CT squeeze program in Alaska, a team of engineers and field supervisors decided to use CT cement squeeze technology to seal the lateral portion of the wellbore and leave a cement base for subsequent sidetracking operations. This paper will discuss the details of this job including:
Cement design and testing
Tools and Equipment
Wellbore geometry and Placement details
Onsite Job Execution details