Blowout Contingency Decision-Making Leveraging Pressure Modeling: Cap-And-Restrain or Cap-And- Divert?

Abstract

Abstract After the MC 252-1 "Macondo Well" blowout on April 20, 2010, in the Gulf of Mexico (GoM), notable efforts were placed on subseawell capping and containment in order to enhance the industry’s response to an offshore-blowout event. The thrust of this paper is the important role that the accurate modeling and monitoring of the reservoir pressure can play in determining the best practice to kill a blown well. A novel workflow is presented for supporting blowout contingency by assisting decision-making across different postblowout intervention strategies integrating reservoir simulation, wellbore mechanics, and the surface equipment’s operating limits. Due to the unique set of challenges for each blowout, a well-intervention method that proved effective in one scenario might not be the optimal for the next—it could lead to failure, or be unimplementable. Proper response to a well-control event of this type is divided into two broad categories. The first category is cap-and-restrain, which requires forward-modeling of the wellbore pressure buildup, identifying the critical post-blowout-discharge-flowrate value, above which it is safe to shut-in the capping stack (CS). The second category is cap-and-divert, which requires the CS to be partially or completely opened with the flow being diverted to an external storage unit. This is done after confirming that the well has sufficient integrity to handle the backpressure of the controlled discharge. This work focuses on the methods and processes planned to contain a subsea blowout either by "cap-and-restrain" or by "cap-and- divert" using an innovative workflow coupled with a generic, multi-purpose, three-dimensional (3D), two-phase (water/oil), reservoir simulator, "Program for Integrated Modeling of Petroleum Systems" (PIMPS3D2P). Once the feasibility of subsea-capping-stack deployment and landing is evaluated, the implementation of a well-kill procedure becomes vital for reaching the static well conditions required. Our innovative workflow has been successfully applied to the Macondo Well’s blowout scenario.