23 May 2010

Prepping BOP for Top Kill; Estimating True Flow Rates

BP has replaced a key control module in the BOP above the Macondo well as it prepares for a top kill that could come as early as Sunday [Tuesday].

BP re-inserted a “yellow pod", one of two in the BOP that will control the choke and kill valves needed to kill the well, a source told UpstreamOnline.

Suttles said BP had two more pressure measurements to take before it could decide definitively to move forward with the top kill option.

In a top kill, BP will pump heavy-weight mud at a high enough pressure to push the flow of oil back down the Macondo wellbore.

The mud will be pumped through a pair of three-inch choke and kill valves located on the lower portion of the crippled BOP.

The heavy mix will then be followed with cement, which would seal the well for good.

BP executive Kent Wells said Sunday that ROVs are preparing pipes and hoses around the well to pump up to 40 barrels per minute of mud into the well.

All of the heavy equipment needed for a top kill “has been mobilised or is on scene”, Suttles said Wednesday, including manifolds, which were dropped to the sea floor late last week.

The Department of Energy has allowed BP to use some of its cutting-edge imaging technology and the latest scans show that there are no obstructions in the wellbore that would preclude a top kill, Suttles said.

Graphics generated by BP show that the Q4000 semi-submersible supply vessel, which is currently operated by Houston-based Helix Energy Solutions, will be used in the top kill operations.

BP representatives said they were unsure if the top kill would be carried out by Helix’s Well Ops division, which offers subsea well intervention services.

It is understood BP's preference for staunching the well flow is to carry out a top kill, but it has other options on the table in the event it does not work.

The next option would likely be a junk shot.

A junk shot entails pumping chunks of rubber, shredded tyres, frac balls and other materials, along with heavy mud, directly into the BOP, Suttles said.

The reason BP likely will start with a top kill over a junk shot is that a failed junk shot could cut off other well control options, he said. _Upstream

Cogdell said estimates as high as 100,000 barrels of oil a day from some scientists were unrealistic based on production rates at deep water wells in the vicinity, which range from 15,000 to 30,000 barrels per day.

Steve Wereley, a professor of mechanical engineering at Purdue University who was thrust into the limelight last week after analyzing a 30-second video clip of the leaking pipe for National Public Radio, said he would likely cut in half his latest estimate of 100,000 barrels of oil a day after viewing a live video feed that was released on Thursday. _Rigzone

The mainstream media is also reporting that so-called exerts are saying the amount of oil being released is far more than the 5,000 barrels thought to be leaking in the ocean on a daily basis by BP. Experts? How is anyone an expert in oil leaking from the ocean floor at about a mile below the surface? There is no such thing as an expert in this...

...One of the major elements that are going to make these so-called researchers and scientists look stupid and ignorant is the fact that about half of what is leaking into the ocean is natural gas. They are basing their inflated numbers on all the liquid being oil, which totally makes the flow far higher than it really is.

Other things not being taken into consideration, are these, according to BP in a statement: "For instance, while the original riser was 19.5 inches in diameter prior to the Deepwater Horizon accident, damage sustained during the accident distorted the diameter at the end of the pipe by about 30 percent. In addition, a drill pipe currently trapped inside the riser has reduced the flow area by an additional 10 percent." _DrippingOil

Part of the problem remains in the complexity of the flow of an expanding gas in oil, coming out into an unconfined (apart from the sea pressure) space. Estimates of the flow have ranged up to 100,000 bd. At the moment the evaluation is relying largely on either visual evaluations, or relatively crude analysis, albeit with sophisticated systems, based on estimated behaviors of the flow volumes. Whether the flow has, as BP have stated, been significantly reduced by the RIT tap, or whether the current tap has had little significant effect is largely, at present left up to individual judgment without measurements of the actual flows. _BitToothEnergy

If you visually compare the pre-siphon flow to the post-siphon flow, you will be in as good a position as anyone (except the insiders with access to real time data) to judge the flow rates -- knowing how much is coming out of the surface end of the siphon tube.

The mainstream media ends up making idiots out of themselves and out of anyone who craves his 15 minutes of fame.

Update: The Flow Rate Technical Group (PDF) will release its assessment of flow rates early this week.
The FRTG is leading a coordinated effort across the federal government to determine oil flow rates from the spill at multiple time periods following the explosion, fire and sinking of the oil rig in order to compute total outflow.

This will be achieved by:

• Obtaining a wide variety of data available on the reservoir, wellbore, blowout preventer,
subsea flowing pressures, leak points, discharge plums and surface discharge observations, and others, as well as video review; and
• Using that data to identify and run state-of-the-art models to calculate flow rates and compare results.

Within the Group are two teams:
• A Modeling Team, which will collect and analyze data, and run state-of-the-art models.
• A Peer Review Team, which will conduct an independent review of all reports and findings of the modeling team under a contract with an independent organization. The FRTG, chaired by MMS National Outer Continental Shelf Oil Spill Program Coordinator David Moore, draws on the experience of the best experts from the federal government, including the U.S. Coast Guard, Minerals Management Service, Department of Energy, NOAA and the U.S. Geologic Survey, as well as members from academia.

The group expects to have an initial flow assessment completed by early next week. _FRTG Factsheet (PDF)


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