Turbidites reservoirs are often "amalgumated" sands.
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Alaska_geo on July 17, 2010 - 1:34pm
I'm strongly suspecting that the reason the pressures are less than expected is because the Macondo well has been in communication with and draining a small compartment, rather that the entire accumulation. This reservoir is most likely composed of turbidite sands. Turbidites reservoirs are often "amalgumated" sands. That is they are deposited by a series of turbidity flows over some period of time. The sands may make one big pile, but are still individual sands. The pre-drill estimate of 50-100 million bbls is no doubt based on seismic data, which does a fair job of indicating the overall size of the sand accumulation. However, seismic is often too blunt a tool to image the individual turbidite sands that make up the whole sand accumulation.
In a compartmentalized reservoir, individual sands aren't well connected to one another. A well draining one sand may get little or no contribution from adjancent sands. In the normal oil field development and production situation a compartmentalized reservoir is a bad thing. It means more wells (hence more cost) are required to produce the field. In the present situation, compartmentalization may be a good thing. It means the last 80+ days of "production" may have drawn down the pressure in the compartment significantly from what was observed when the well was initially drilled.
That is a distinct possibility and sedimentary deposits may have combined to scew the original estimate.
Still.... that was a huge a variance but, Thank God Obama and his experts stopped the leak... for now.
An exercise in pronoun selection.
Is Obama Claiming Credit for Gulf Spill Solution?
THE PRESIDENT: Good morning, everybody. I wanted to give everyone a quick update on the situation in the Gulf. As we all know, a new cap was fitted over the BP oil well earlier this week. This larger more sophisticated cap was designed to give us greater control over the oil flow as we complete the relief wells that are necessary to stop the leak.
Now, our scientists and outside experts have met through the night and continue this morning to analyze the data from the well integrity test. What they’re working to determine is whether we can safely shut in the well using the new cap without creating new problems, including possibly countless new oil leaks in the sea floor.
Now BP’s scientists are the “Scientists formerly known as They”
Entire post at: http://www.freerepublic.com/focus/f-news/2554385/posts
I fully expect after his little mini holiday is over we will hear about leaks from the seafloor. I hope that I’m wrong.
BELEAGUERED energy giant BP was hit with further bad news this morning as it emerged dangerous arsenic levels have been found in seawater around the Gulf of Mexico.
British scientists warned that the oil spill is increasing the level of arsenic in the ocean, and could further add to the devastating impact on the already sensitive environment.
BP’s Deepwater Horizon rig has been spilling between 3,681,500 litres and 911,454,000 litres of oil into the sea per day since it exploded on April 22.
They said the arsenic then gets “magnified” up the food chain, as fish eat small amounts of the deadly poison and may eventually impact humans, researchers said.
Professor Mark Sephton said arsenic, which is found in seawater, was normally filtered out of the ocean when it combined with sediment on the sea floor.
“But oil spills stop the normal process because the oil combines with sediment and it leads to an accumulation of arsenic in the water over time,” he said.
“Arsenic only needs to be a 10th of a part per billion to cause problems.”
He added: “Our study is a timely reminder that oil spills could create a toxic ticking time bomb, which could threaten the fabric of the marine ecosystem in the future.”
http://www.news.com.au/world/more-bad-news-for-bp-as-arsenic-levels-rise-in-seawater-around-the-gulf-of-mexico/story-e6frfkyi-1225888272667
http://www.nypost.com/p/news/national/gulf_toxic_bomb_xgOomKo8AQzXKzc8aSxh0K
A truly educated take on the pressure drop. Thanks for posting and hopefully giving the “Doomsday Drama Queens” something to think about.