Modeling and Simulation of Annular Pressure Buildup (APB) Mitigation Using Rupture Disk

Abstract

Abstract Manufactured to burst/collapse at a specific pressure difference and installed in the casing wall, a rupture disk is a common device used to mitigate annular pressure buildup (APB) and to protect casing strings. This paper focuses on the modeling and simulation of the effects of a rupture disk burst/collapse event on APB in casing/tubing annuli. After the rupture disk bursts (or collapses), fluid will move through the open disk from one annulus to another, resulting in changing pressures. In this work, three pressure balance models (piston model, miscible fluid model, and immiscible fluid model) were established to calculate the annulus fluid pressure and volume changes after the rupture disk opens. The piston model, assuming no fluid exchange between two annuli, provides the simplest solution. It is accurate if the two annuli contain nearly identical fluids. The miscible fluid model is intended for annuli with the same fluid type, but with different density values. The immiscible fluid model is intended for annuli with different immiscible fluid types, such as oil-based mud in the internal annulus and water-based mud in the outer annulus. The pressure balance models were implemented and integrated into a commercial casing and tubing design software platform. A numerical approach was used for trapped and connected annuli; an analytical approach was used for connected annuli with at least one ventilation or leakoff point. This combination provides optimized simulation performance and accuracy. When multiple annuli are connected with open rupture disks, global pressure equilibrium is reached through iterations of handling two connected APB regions at a time. In a case study in which the casing ballooning effect is negligible, numerical simulation results were found to be consistent with the results of analytical calculation; the difference is within 0.1%. The application of the rupture disk for APB management was also demonstrated in another case study using field data. The simulation results show that the rupture disk is a viable and cost-effective option for APB management.