Deepwater Casing Design with Annular Pressure Build Up Mitigation Using Rupture Disk

Abstract

DWP-1 Well is a subsea well, located in the deepwater area of Indonesia. This well presents challenges in managing annular pressure build-up (APB) due to the unique casing design considerations. The only accesible annulus for the subsea well is the tubing string annulus and the other annulus pressure can’t be controlled at the surface. The Top of Cement (TOC) of the production casings, is not set back to the surface and due to the well planned to penetrate productive layer which have to be covered, so the TOC was set above prior shoe, leaving the fluids above TOC in a confined sealed space, inside the annulus. This fluid will be subjected to the temperature change due to produced fluid, which induced a great temperature change during production phase. This can potentially lead to APB issues. It is crucial to design the casing configuration to withstand APB and maintain the integrity under both drilling and production loads. This research aims to determine the optimal casing design for the DWP-1 Well, considering APB mitigation strategies. A series of casing design analyses were conducted using StressCheckTM software, while APB calculations were carried out using WellCatTM software from Halliburton Landmark. Simulation results that although the initially designed casing could withstand anticipated drilling and production load scenarios, it failed to withstand APB loads. However, when a rupture disk was simulated and installed as an APB mitigation plan, the same design successfully passed the APB loads. This indicates that the proposed casing design, with the inclusion of a rupture disk, is suitable for use in the DWP-1 Well.