For many years perforating in horizontal wells under variable conditions has been one of the biggest challenges in the South China Sea area. Being a critical step during the cycle of a well, operators have to identify the best perforating method to achieve desired results in the safest manner whilst remaining cost-effective. Perforating using coiled tubing (CT) conveyance provides a range of flexibility as an attractive method to convey long sections of guns in a single run; however, whether this technology can be considered the most appropriate solution in light of available alternatives developed in recent years, remains in question.

One of the operators in Malaysia faced this situation when preparing its first perforating campaign in a field with complex extended reach wells, where the main target was to produce the maximum quantity of gas available whilst avoiding sand production. The campaign was performed with a rig present and any delay due to failure meant a huge cost impact. The operator solicited a detailed technical design and a systematic evaluation of all available options in the market to perforate the pay zones successfully.

The solution implemented was based in part on the experience obtained during previous years in the area, where different methods were used. An exhaustive statistical analysis was performed to determine the critical parameters to be the focus of the design and the selection of the most reliable technology to address the various scenarios that the campaign presented. Hydraulically actuated CT tractors, friction reducers, stealing beads, and creative use of buoyancy effect, together with using state-of-the-art CT technology were among the combinations proposed to overcome CT lockup and successfully convey the oriented guns to total depth (TD) in all wells.

The intent of this paper is to provide a strong guide to CT perforating under variable conditions in horizontal wells through a thorough requirements analysis, risk evaluation and proper selection of technology. A review of the results and lessons learnt are also included. The engineering process, which has since become the benchmark in the area, can be applied with confidence as evidence by the success of the campaign.