Containment
System

MWCC’s main goal is to shut off the flow of fluids from a compromised well using a primary containment device called a capping stack. A capping stack is a series of valves that can be installed on top of a compromised well to shut off the flow of fluids.

The drilling assembly on the seafloor, which consists of the Blow Out Preventer (BOP) and Lower Marine Riser Package, is massive and about 60 feet tall. This size is comparable to two school buses stacked end-to-end weighing almost 400 metric tons, or about the same as 68 elephants. An incident in a structure this large requires a similar sized containment solution. MWCC’s capping stacks are taller than a two-story building with a maximum weight of 112 metric tons, which is about the same size as 45 full-sized SUVs. Each capping stack has been purpose-designed and built to ensure MWCC can respond to a diverse array of scenarios effectively.

MWCC has four capping stacks in its portfolio ranging in size and capability. Each capping stack is capable of operating in depths ranging from 500 to 10,000 feet of water. Members submit each specific well design to MWCC’s engineers to be evaluated for system compatibility. Additionally, MWCC engineers validate Operators’ containment plans and cite one of our four unique capping stacks to best fit the needs of every well. To meet the demands of our members, MWCC’s capping stack portfolio advances with industry drilling capabilities, especially around higher pressure and temperature reservoirs of hydrocarbons. Our portfolio of capping stacks is designed to manage well fluids up to 20,000 PSI of pressure and up to 400 degrees Fahrenheit. MWCC has engineered our capping stacks to attach to a variety of locations on a compromised well, such as the marine riser adaptor, the top of the BOP, directly on top of a wellhead or secured on the well casing. To achieve flexibility in capping stack connection, MWCC has a variety of connectors that we can change out to fit the unique needs of an incident. Further, MWCC has the first industry wellhead straightening tool. This piece of equipment works like a chain jack to pull a damaged wellhead into a more vertical position for easier connection of a capping stack.

Similar to how dish soap breaks up grease when washing a frying pan, MWCC has dispersant injection equipment to break up hydrocarbons at the wellhead, which helps to protect responders and reduce environmental impact. Dispersant injected at the wellhead breaks up oil at the point of release and limits the collection of well fluids at the surface of the water. Dispersants have been used for decades to break up pooling hydrocarbons, which protects Responders from volatile organic compounds (VOCs) and allows safer access to the compromised well.

In the past, dispersant was typically applied at the surface of the water or dropped from the air after well fluids had accumulated on the surface. MWCC is among the first to have subsea dispersant equipment capable of pumping dispersant directly into the well at the point of release, up to two miles below the surface. Subsea application has proven more effective than surface applications and can require up to five times less dispersant solution than traditional methods.

Dispersant application must be authorized by the Environmental Protection Agency (EPA) through a request and approval process initiated by the Well Operator. The EPA determines if and how subsea dispersant should be used in an incident. If dispersant is approved for use, the amount applied is set by the EPA.

To support the Well Operator and Regulators in ensuring that dispersant use is limited to only what is needed, MWCC maintains and operates a Water Column Monitoring System to help the Well Operator optimize injection rates. MWCC was the first source control provider to have this dedicated technology, which allows for real-time sample collection and analysis of sea water at various depths from the well site up to the surface.

MWCC’s Subsea Dispersant Injection System (SDIS) pumps dispersant from a marine vessel on the surface through a system of flexible piping to an applicator positioned at the release point.

In the early stages of well fluid collection, MWCC has a series of devices that can be conveyed on drill pipe and positioned over top of the subsea leak to begin collecting some of the leaking hydrocarbons.

MWCC has five top hats and three riser insertion tube tools (RITT) in its portfolio. A top hat basically works like a funnel, sitting over top of a leaking well, collecting oil and directing it to a drilling rig on the surface for disposal. A RITT looks a lot like a straw that can be inserted inside of a broken riser pipe to collect and direct oil to a drilling rig for disposal.

For longer term flowback, MWCC can create a closed loop system to contain the leaking well fluids while relief wells are being drilled. MWCC would still install the capping stack but rather than shutting off the flow, a series of piping and flowlines connected to the capping stack are used to route well fluids through a riser flowback system up to the host rig which can be located up to a mile away from the incident site.

The closed system architecture is tailored to site specific requirements including water depth, seafloor landscape, well rates, ocean currents and debris field. For well control events that are 25,000 barrels per day or less, the rig-based system may be sufficient by itself to provide full well containment.

Should fluid rates be greater than the capacity of our rig-based system, MWCC has a ship-based flowback system consisting of an oil tanker that has been customized to receive additional hydrocarbon capture equipment.

The vessel, known as the Modular Capture Vessel (MCV), can capture up to 75,000 barrels of oil per day and flare up to 150 million standard cubic feet per day of natural gas. At about 800 feet long, the MCV is larger than a mid-size cruise ship and has the capability to separate the oil and flare, or burn off, the natural gas. Separated water, oil and sand are stored in the tanker’s hull and can be offloaded to a shuttle tanker when capacity is reached.

The MCV also has Dynamic Positioning (DP2) capability which allows it to maintain a fixed position without anchors. The MCV can also be stationed up to a mile away from the incident site to reduce response traffic directly over the well site and increase the safety of our Response Team by keeping them away from the oil discharge.

Connection from flexible piping on the seafloor up to the MCV is made using a free-standing riser comprised of a series of vertical pipes that are connected and suspended in the water from the seafloor using giant buoyancy cans.

The Ship-Based system can be used by itself or in combination with the Rig-Based System. Combined, MWCC’s flowback system can capture up to 100,000 barrels of oil per day and 200 million standard cubic feet per day of natural gas. For perspective, that’s enough oil to fuel about 2 million cars, and enough natural gas to power about 1 million homes, at typical consumption rates.