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.

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.

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.

Two significant development projects were being planned for brownfields in southeast Asia with a total of seven platforms and 230 wellbores in place. Previous drilling campaigns were conducted from 10 to 30 years ago. Hence, existing data were of variable quality and reliability. During the design process for both fields, it was determined that there were large discrepancies and irregularities between well positioning databases. This not only complicated the anticollision situation of drilling in the congested fields but could also influence the reservoir model accuracy for determining the development target. The anticollision risks based on the existing data meant that well plans had to be "over engineered" to avoid the perceived risks while also requiring offset wells to be shut in during drilling operations. Thus, both drilling efficiency and production were affected because of the well positioning uncertainties. A comprehensive survey management process was embarked upon by both the operator and service company to ensure that the survey databases being used by the drilling and subsurface teams were consistent and free from gross errors. This included the review of all existing survey reports, sources of platform positions, etc. to identify anomalies or gross errors. This was the first such project conducted by the operator. This paper discusses the complete survey management validation process and also highlights its effect in allowing the safe and efficient well planning of the drilling campaigns while providing the subsurface team an accurate well positioning database to allow accurate target selection.