Integrated Technology Approach to Explore Carbonate Reservoirs in Malaysia Enhances PMCD Potentials and Enables Successful Prospect Evaluations

摘要

The Central Luconia province located in offshore Sarawak (East Malaysia) houses numerous carbonate reservoirs. Some of these reservoirs, especially the pinnacle structures are characterized by the presence of karsts and fractures leading to total mud losses. PETRONAS has been exploring carbonate reservoirs in this area since the 90s. However, as more prospects being explored, the challenge intensifies as the company embarked into exploring remaining carbonate pinnacle structures with primary objective of identifying the gas water contact (GWC) of the prospects. Drilling the well conventionally risk the operations not just in its safety aspect but also deliverability of the well objective and data acquisition plan. Implementing the variant of the Managed Pressure Drilling (MPD) technology called Pressurized Mud Cap Drilling (PMCD) allowed targeted total depths to be reached on several wells. However, reaching total depth alone is not sufficient, as the prospect has to be conclusively evaluated. With the limitations in Logging While Drilling (LWD) capability, prevalent high vibrations in the carbonate section and heterogeneity of the formations, delivering a conclusive formation evaluation result to identify GWC often necessitates acquisition of pore pressure data in the carbonate section – in total losses condition. This mission remains as a big challenge to the industry, which could not be solved by PMCD technology alone. Integration of technology applications is paramount to increase the success rate of data delivery. The authors present case histories of wells drilled to date, integrated strategies approach employed and lessons learnt as the operator evolves to enhance its carbonate drilling & evaluation capability. The use of Seismic While Drilling (SWD) for reducing top of carbonate uncertainty, the successful use of Composite Bridge Plug (CBP) to isolate wellbore against total losses, formation evaluation strategies in total losses condition, and well killing strategies post a production test are among the areas that will be comprehensively covered in this paper.