The interim containment system — available for use in the deepwater U.S. Gulf of Mexico since February 2011 — is the result of unprecedented industry collaboration and improves previous response capabilities. The industry’s goal is that the containment system will never be needed, but Marine Well Containment Company (MWCC) maintains the system in a ready state.

About the System
The interim containment system meets the needs of all member company wells currently being drilled in the deepwater U.S. Gulf of Mexico. The interim containment system can handle pressure up to 15k psi. The capping stack can cap a well in deepwater depths up to 10,000 feet. It is built to cap and flow a well in deepwater depths up to 8,000 feet. The system has the capacity to contain 60,000 barrels per day (and 120 million standard cubic feet per day) with potential for expansion and includes a 15k psi single ram capping stack and dispersant injection capability. Through mutual aid released by members, the interim containment system includes capture vessels for surface processing and storage.

The centerpiece of the system, the capping stack is a massive piece of equipment, about 30 feet tall including the necessary lifting gear, 14 feet wide and weighing 100 tons. The capping stack provides a dual barrier for containment - a blowout preventer ram, plus a containment cap. The valves can be closed to cap the well, or if necessary, the flow can be redirected to surface vessels through flexible pipes and risers.

In designing the system, MWCC worked with regulators from the Bureau of Safety and Environmental Enforcement (BSEE) to ensure all expectations were met and that the new system would not only safeguard the U.S. Gulf of Mexico, but allow new permits to be issued. MWCC has continued to stay in regular communication with BSEE, including onsite reviews and witness testing of the capping stack, a review of the interim containment system equipment, and a demonstration of the system in the U.S. Gulf of Mexico during the summer of 2012. BSEE has also participated in a Responsible Party checklist workshop for member companies, as well as TLP/SPAR checklist development workshops.

In June 2013, MWCC announced the availability of a dual ram 10k psi capping stack for use in the deepwater U.S. Gulf of Mexico. The completion of the 10k psi capping stack — which stands 25 ft. tall including the necessary lifting gear and weighs approximately 50 tons — is an addition to the original 15k psi capping stack, and marks another step in MWCC’s commitment to advancing well containment capabilities in the deepwater U.S. Gulf of Mexico.

With a footprint of 9 ft. by 9 ft., the 10k psi capping stack is designed to reach deepwater areas where well casings and riser systems are closely spaced, such as tension leg platform (TLP) applications where wells are beneath a floating production facility. The new dual ram capping stack, designed by Shell and constructed by Trendsetter, can cap a well in depths of up to 10,000 feet.

Containment Scenarios
There are two primary containment approaches: "cap only" and "cap and flow." "Cap only" refers to when the capping stack is attached to the well and the ram and four outlets are closed to shut off the flow of fluids from the well. "Cap and flow" is used when it is necessary to flow a well. In this situation, the system redirects the flow of fluids through flexible pipes and risers to surface vessels for processing. The liquid is then transferred and offloaded to a shuttle tanker.

Containment equipment utilized in a "cap only" scenario.

Containment equipment utilized in a "cap and flow" scenario.