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Lower Marine Riser Package (LMRP) Cap will succeed – BP oil spill

June 5, 2010

LMRP Cap will succeed to seal the BP oil well, have a doubt?

With the President Obama’s third visit to the Gulf of Mexico coast, the progress of the latest attempt known as the LMRP Cap method, also the third attempt, to the seal the BP oil spill emerged in front of public.  What is the LMRP cap method?.

It is to put the sealing cap on the top of the blowout preventer (BOP). if the sealing cap can be successfully installed on the top of the BOP, the oil spill can be stopped.

The deep sea water is lack of light, underwater robots also called Remotely operated vehicles (ROV) are being used to provide the light.  Only with the sufficient light sources, the sealing operators can  start to work

Three major steps of the the LMRP Cap method

(1) Cut the pipe, which is being used to collect the oil, which is not the core work in the LMRP method. The cut will be conducted by a sears, with one  underwater robot to provide light.

(2) Cut the BOP, the cut will yield a clean surface for the cap, the grommet to be installed. The cut will carried out by the diamond wire cutter, with the assistance of underwater robot.

(3) Put the Cap on the BOP, after getting a clean-cut BOP surface. The Cap, with a sealing grommet, will be installed on the top of BOP.

What are the risks?

(1) It is relatively easy for the first cut to be successful. It is not a very complex process, without too much precision involved.

(2) The second cut could be challenging.  The second cut has to leave a clean, nice cross section for the cap to seat on. Any mistakes will lead to the failure of LMPR method. How hard to get a clean cut surface? It can take time to do this work. The oil is still ushered away from the BOP, which can generate forces according to the Bernoulli equation.  The force on the cutter generate the imbalanced moment.  Such moment on the cutter can lead to mechanical problem  (such as broken, jam) of the cutter.  As shown in the previous article, Do not feel frustrated- BP oil spill, the top-kill method failed, however, the top-kill helps to reduce the flow of oil, which also reduce the forces on the cutter. As such, it becomes feasible for the cutting task to be carried out.

(3) The Cap’s vertical position has to be well controlled. Otherwise, the cap is not going to exactly seat on the top of BOP.

LMRP  Cap will succeed

Why the LMRP Cap method will succeed?  Two simple key points.

(1) 1st Cut, 2nd cut, It is tolerable for the first cut to be imperfect.  It is critical however for the 2nd cut to leave a clean surface.  How hard is it?  It has already been reported that the diamond wired saw did not perform well, which has gotten stuck.  BP can use its backup saw, which takes time to do, but doable.

(2) Cap installation, If there is anything wrong in the Cap installation process, the Cap always can be readjusted to make it well seated on the top of BOP.

What if the prediction is wrong and the LMRP Cap fail in the future?

If LMRP failed, then in theory, there are not many easy available methods to be used. Of course, the BP engineers can invent some new methods to seal the BOP, but it will take time to do.

These videos can help you for conceiving the LMRP Cap method: (updated on 6-6-2010, 6:33 PM)

The following high resolution images are cited from BP (Accreditation). It can help you to understand the LMRP Cap process better.

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