A Novel Engineering Approach in Drilling an ERD Well in a Carbonate Field, Malaysia

In order to extract the remaining reserves from a depleted carbonate field as well as to explore the possibility of finding additional reserves in a new fault block, PETRONAS is required to drill an Extended Reach Drilling (ERD) well from the existing platform in the FX field. The new target block is located approximately 4 km from the existing platform. This paper summarizes the planning challenges as well as the solutions in delivering the ERD well in a carbonate reservoir. During the design phase, the team put a high emphasis in avoiding any complications while drilling an ERD well in a carbonate reservoir especially in managing severe or total losses. As such, the subsurface team came out with a novel approach in mapping the karst in the carbonate reservoir allowing optimum placement of the well trajectory. With the optimized target, the well was designed accordingly, addressing all the challenges that were raised during the detailed risk assessment such as hole cleaning issues, wellbore instability, Equivalent Circulating Density (ECD) management, Torque and Drag (T&D) during drilling as well as running casings/liner, cement integrity in high angle well etc. An ERD consultant was engaged to facilitate the design and execution phases. The final well design and implementation plans were finalized with the ERD consultant's assistance which addressed all the anticipated challenges. An Advanced 1D Mechanical Earth Model (MEM) was constructed with the latest offset data to determine the proper mud weight window to drill the ERD well. The finalized Torque and Drag simulation provided the necessary strategies in completing the well including expected drilling parameters as well as delivering the casing and liner to bottom. Ensuring cement integrity while managing ECD by implementing new technology was also planned. The new technologies and specific approaches implemented to deliver the ERD well in a carbonate reservoir include detailed Seismic analysis to detect and predict the presence of karst in the carbonate, Pseudo Catenary well trajectory to optimize the well trajectory, 9-5/8" liner full air flotation to get the liner to bottom, Definitive Survey While Drilling to reduce vertical uncertainties as well as minimizing the stationary time and flow diverter to ensure cement integrity especially in the high angle / horizontal sections.