How To Develop a Well-Specific Capping-Stack Blowout Contingency Plan

Topics: Subsea systems Well integrity/control
Fig. 1—In the CFD model, the capping stack is lowered onto the jet of the blowout, in this case for a partially bent wellhead.

The planning process for developing a well-specific subsea-capping contingency plan involves assessing the feasibility of deploying a capping stack from a floating vessel, determining the weight and stability of the capping stack to overcome the force of the blowout jet, and performing dynamic-flow simulations of closing the capping stack outlets without loss of well integrity. This process not only assesses the feasibility, complexity, and risk exposure of the capping operation but also may justify further planning, studies, or expenditure.


Blowout-kill techniques can be classified as either surface-intervention or relief-well methods. Relief wells aim to kill a blowout from the bottom by injecting fluid into the wellbore until the influx of formation fluid is stopped and the well is static when pumping stops. In many cases, a relief well will be the safest intervention and have the highest likelihood of success, and often it is considered the last line of defense against a blowout. Surface interventions are kill attempts aimed at controlling the discharge at the wellhead or at the fluid-exit point. An example is to install a capping stack on top of the wellhead and close its openings, which can be gate valves, chokes, or rams.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 181393, “How To Develop a Well-Specific Blowout Contingency Plan That Covers Engineering Analysis of the Deployment, Installation, and Soft Shut-In of a Subsea Capping Operation,” by Ray T. Oskarsen, SPE, Morten H. Emilsen, SPE, and Amir S. Paknejad, Add Energy; Mike Cargol, Trendsetter Engineering; and Kwee Choong See, SPE, Shell International Exploration and Production, prepared for the 2016 SPE Annual Technical Conference and Exhibition, Dubai, 26–28 September. The paper has not been peer reviewed.
This article is reserved for SPE members and JPT subscribers.
If you would like to continue reading,
please Sign In, JOIN SPE or Subscribe to JPT

How To Develop a Well-Specific Capping-Stack Blowout Contingency Plan

01 February 2017

Volume: 69 | Issue: 2