Completion operation is one of the most important contributors to successful well deliverables. Without a proper design of the accessories and efficient operation in conveying the completion assembly, the true potential of a well may not be realized. Coiled Tubing Drilling (CTD) was first attempted in Peninsular Malaysia in February 2011 and the wells were designed to be completed as Coiled Tubing (CT) re-entry sidetrack using 2-3/8" pre-drilled liner and swell packers with maximum inclination of 90° angle and dogleg ranges between 30-60° per 100 feet. The liner and swell packer assembly were designed to be conveyed to the target zone via coiled tubing and to go through 3 ½" tubing with maximum clearance of 2.8" and dual casing exit from the existing completion setup. Apart from the small and rigid clearance, another challenges that the team faced was differential sticking due to mud property that was used to maintain hole stability and to prevent the hole from collapsing before the completion was placed. Since the completion would be conveyed through high dogleg environment, the type of liner and swell packer chosen had to able to withstand the bending stresses applied to it. A small error will result in parted assembly or inability for it to be conveyed all the way to the intended zone. This paper presents the challenges faced during the design and completion operations and discusses the program devised to overcome the above mentioned issues. Based on the lesson learnt from previous wells in which the operations were not 100% successful, the team made significant improvements in terms of mud property, swell packer design, procedure changes and introduction of friction reducer into the completion program of the final and last well of the campaign that finally enabled the liner to be conveyed to the total depth (TD) successfully.

Cementing through coiled tubing electric line (CT e-line) is not a common practice; this application is highly recommended in Coiled Tubing Drilling (CTD) applications using the existing CT e-line pipe to achieve a better time performance for sidetracking a well since using the CTD technique is mainly based on economical evaluation. Several considerations need to be taken into account while designing the job and performing the operation. The relatively high density and viscosity fluid can lead to bird nesting the cable due to high friction and excessive slack inside the pipe; it can also affect the integrity of the cable as well as the performance of the bottomhole assembly (BHA). The interface between cement and other fluids pumped through CT e-line pipe can be also affected. A review on a feasibility study of cementing through CT e-line that was performed in 2003 in Alaska highlights all the concerns, challenges, and potential issues that can be encountered during a cementing job through CT e-line, best practices, lessons learned, and way forward to implement this technique. This review is supported by two successful case histories performed in Malaysia CTD campaign applying this technique for different objectives: remedial cementing for casing and tubing sealing in a deviated well and remedial cement plug for window recovery. By implementing cementing through CT e-line, the effective job time was improved by avoiding swapping pipes in an offshore environment where the logistic, safety, and space accommodation is a huge challenge. The use of CTD as an economical sidetracking technology was reinforced by making the CT e-line pipe universally utilized in all the project steps, even for running and setting completion.

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, sterling 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.

The sustained and relatively high value of oil and natural gas has resulted in an unprecedented level of drilling activity and implementation of innovative methods to recover as much hydrocarbon as possible, and as quickly as possible. The resulting demand for conventional drilling rigs for programs has forced the rates high and the availability low, making use of the units difficult to justify for use in declining fields with less significant amounts of recoverable product. The by-passed reserves remaining accessible in these depleted fields exist in volumes worthy of pursuit, but must be done economically. In many fields, operators, either intentionally or unintentionally, bypass pay zones during initial development by focusing only on the best zones. Accessing bypassed thinly laminated formations can be economically attractive but poses several challenges, especially due to aged platforms and completion string in place, also offshore environment is adding its own challenges. Coiled Tubing Drilling (CTD) has yet to establish itself in an offshore environment. Numerous one-off projects have been tried, but commitment was never made to a number of wells to see through the learning curve and realize the potential of the application. Offshore South China Sea have a huge quantity of candidates on existing installations, installations that, due to water depths and sub sea conditions require large, expensive rigs to drill or re-enter wells. Technically the wells can be accessed with coiled tubing with drilling parameters seen regularly in other projects. The challenges for this pilot project will be equipment specification and set up, efficiently exiting the casing, and management of wellbore stability in open hole drilling and completion techniques. The main objective of this pilot project is to bring proven technology to offshore environment to access small bypassed reserves economically and provide an alternative to conventional drilling. The well candidates were selected with strict work scope to avoid going beyond the regular CTD application to ensure learning curve and lessons learned can be implemented throughout the project and achieve the objective. This paper will described the preparation, execution, achievement and lessons learned from this 4 wells pilot project in offshore South China Sea.

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