With the current uncertain situation regarding the stability of oil prices in the world, operators have been pushed to develop their available resources in a cost-effective way. Lately, there has been increased interest in the application of Coiled Tubing Drilling, especially for accessing bypassed hydrocarbon in mature or late-stage fields. This paper describes the feasibility study done to examine the possibility of using Coiled Tubing Drilling package/equipment to drill and complete a sidetrack well in a karstic carbonate reservoir with total losses issue by applying the principles of Pressurized Mud Cap Drilling (PMCD). This will be the first time that such method is being utilized for developing karstic carbonate reservoirs in Offshore Malaysia. The paper will go through the background of the project (generic field information, reservoir properties, well design and architecture), the critical design elements for the system (technical requirements, safety standards, operational and logistical factors) and the contingency scenarios considered. Based on the aforementioned items, a fit-for-purpose Coiled Tubing Drilling equipment arrangement together with suitable PMCD method and light annular mud (LAM) selection were proposed to cater for the specific challenges of the well. It was concluded that the application of PMCD using Coiled Tubing Drilling Package is feasible with some modification to the equipment, line up and operational procedures.