This paper presents a general discussion of the phases necessary to undertake coiled tubing drilling (CTD) project in a new area: conceptual design during the feasibility study, equipment planning and preparation, detailed engineering, and operational challenges during execution. The actual operations and performance results for these phases are given for the first CTD pilot project undertaken in Malaysia.
CTD can provide significant economic benefits when applied in the proper field setting. In addition to potential cost advantages, it can provide other benefits: safer and more efficient pressure control, faster tripping time, smaller footprint and weight, faster rig-up and rig-down, reduced environment impact, operations with fewer personnel, and high-speed telemetry. In the Malaysia project, where it was applied to the drilling of directional through-tubing reentry wells requiring casing exit methods and high dogleg capability, it provided the flexibility to access compartmentalized bypassed pockets in the reservoir. Drilling for the CTD project was started in February 2011 and completed in August 2011; three out of four wells were drilled and completed in the target formation. The challenges faced during the beginning of the execution phase were used as lessons learned and contributed to a fast learning curve, leading to delivery of the last three wells within budget.
The drilling campaign demonstrated the ability of CTD to reach small, bypassed pockets that are difficult to produce economically with conventional reentry drilling techniques. This success has opened the door for CTD of other numerous idle wells [in same field or just in Malaysia in general?], which can result in efficient recovery of the bypassed oil. This is especially important for the offshore environment of Malaysia because platforms require a significant investment that is usually not justified for such marginal reserves.