Video: LMRP cap istallation (June 5, 2010)
BP Releases Details of Lower Marine Riser Package (LMRP) Cap Procedure
Installing a Lower Marine Riser Package (LMRP) Cap is a containment option for collecting the flow of oil from the MC252 well. The LMRP is the top half of the blow out preventer (BOP) stack.
The installation procedure first involves removing the damaged riser from the top of the BOP.
A remote operated hydraulic shear will be used to make two initial cuts and then that section will be removed by crane. A diamond wire saw will then be placed to cut the pipe close to the LMRP and the final damaged piece of riser will be removed.
The LMRP Cap is designed to seal on top of the riser stub. The seal will decrease the potential of inflow of seawater as well as improve the efficiency of oil recovery. Lines carrying methanol also are connected to the device to help stop hydrate formation.
The device will be connected to a riser extending from the Discoverer Enterprise drillship.
The LMRP Cap is on site, and it is anticipated that this option would be available for deployment by the end of May.
Schematic of LMRP Cap procedure is outlined on drawings below.
There is too much pressure coming from the well. I suggest pushing either a stream of heavy drilling fluid through choke and kill lines (Scenario A) or a stream of methanol (Scenario B).
In the first scenario the heavy drilling fluid can reach up to 10% penetration into the well, as we saw on Friday May 28, and will reduce gases and oil from coming out of BOP opening set for LMRP cap connection. This is a preferable method because it decreases risks of gas “kicks” and reduces chances of gas explosion on Enterprise Drillship when they start “receiving” mix of mud & oil at the surface. The drillship should be ready to siphon mud & oil mixture out of LMRP cap upon cap connection to BOP pipe opening. It is likely BP needs to continue pumping mud into choke and kill lines to minimize impact of gas “kicks” and to have a better control over well’s pressure.
In the second scenario a stream of Methanol through choke and kill lines will dilute gases and oil coming out of the well and prevent them from forming icy slush upon contact with cold ocean water (hydrates, clathrates) and will increase chances of successful connection of LMRP cap to BOP opening. The problem with this method is Enterprise Drillship will need to prepare for possible gas “kicks”. Using mud is a preferable option as it allows for better control over well’s pressure.
A stream of methanol from LMRP cap will decrease icy slush, but likely is not sufficient to combat large amounts of gas from MC252 well. This well is prone to gas kicks. As Kent Wells said it has more gas than BP originally thought.
After Top Kill failed, the decision was made to proceed with LMRP Cap installation, a backup plan. Schematic below depicts installation process and equipment needed for this operation.
Graphics adopted from DeepwaterHorizonResponse.Com ; Source: http://bit.ly/dDmgOH
BP issued an update at 8:40pm Saturday, May 29, 2010 regarding their efforts to stop oil flow from the MC252 well in the Gulf of Mexico. Source: http://www.bp.com/genericarticle.do?categoryId=2012968&contentId=7062487
BP started the “top kill” operations to stop the flow of oil from the MC252 well in the Gulf of Mexico at 1300 CDT on May 26, 2010. The procedure was intended to stem the flow of oil and gas and ultimately kill the well by injecting heavy drilling fluids through the blow-out preventer on the seabed, down into the well.
Despite successfully pumping a total of over 30,000 barrels of heavy mud, in three attempts at rates of up to 80 barrels a minute, and deploying a wide range of different bridging materials, the operation did not overcome the flow from the well.
The Government, together with BP, have therefore decided to move to the next step in the subsea operations, the deployment of the Lower Marine Riser Package (LMRP) Cap Containment System.
The operational plan first involves cutting and then removing the damaged riser from the top of the failed Blow-Out Preventer (BOP) to leave a cleanly-cut pipe at the top of the BOP’s LMRP. The cap is designed to be connected to a riser from the Discoverer Enterprise drillship and placed over the LMRP with the intention of capturing most of the oil and gas flowing from the well. The LMRP cap is already on site and it is currently anticipated that it will be connected in about four days.
This operation has not been previously carried out in 5,000 feet of water and the successful deployment of the containment system cannot be assured.
Drilling of the first relief well continues and is currently at 12,090 feet. Drilling of the second relief well is temporarily suspended and is expected to recommence shortly from 8,576 feet.