Low pressure reading may suggest well has lost power, not that it's leaking

[StackerKen]

Professor: Low pressure reading may suggest well has lost power, not that it's leaking

Published: Friday, July 16, 2010, 12:19 PM Updated: Friday, July 16, 2010, 3:43 PM
Jaquetta White, The Times-Picayune

As a team of scientists works to interpret pressure readings inside the blown-out Macondo well in the Gulf of Mexico, a geologist who has been following the gusher said a pressure reading of lower than the 8,000 to 9,000 pounds per square inch target that officials have said they are hoping for does not necessarily indicate bad news.
The 6,700 pound- per-square inch pressure reading logged inside the blown-out Macondo well this morning may suggest that the well has lost power over the almost three-month-long period it has flowed into the Gulf of Mexico and not that the well is leaking somewhere beneath the sea floor, a geologist who has been following the gusher said.

The reservoir could have "deflated" since it began leaking April 20, reducing the amount of pressure it is capable of producing, said Don Van Nieuwenhuise, Director of the Professional Geoscience Programs at the University of Houston.
A team of scientists and engineers will use the pressure readings to determine if the well can remain shut in.
National Incident Commander Thad Allen has said that the well could be permanently shut in, meaning oil would not flow into the Gulf from the well again, if pressure reached 8,000 to 9,000 pounds per square inch, but that surface oil collection might have to resume if pressures do not reach that level. The lower pressure would indicate that oil was escaping through holes in the well and into the rock formation surrounding it.

But Van Nieuwenhuise said this morning's 6,700 pounds per square inch reading should not cause worry.

"I don't think it's a cause for immediate concern, because it could reflect a natural loss of oil in the reservoir," Van Nieuwenhuise said. "It's amazing that it has held its strength for as long as it has."
Six remote control vehicles monitoring the subsurface area around the well had not detected oil as of Friday morning. BP plans to conduct a seismic survey of the area to get a more detailed view of the area surrounding the well. The results of that survey won't be available until Saturday.
Van Niewenhuise said the lack of any sign of oil so far is a good sign.

"When they first said this, I said if they can get to 7,000 (pounds per square inch) that would be good," Van Nieuwenhuise said. "The 8,000 to 9,000 estimate reflects its initial pressure, but since it's been bleeding so much, I'm not surprised it's at 7,000."



http://www.nola.com/news/gulf-oil-spill/index.ssf/2010/07/professor_low_pressure_reading.html (http://www.nola.com/news/gulf-oil-spill/index.ssf/2010/07/professor_low_pressure_reading.html)

[ximmy]

slightly different view here...

The bottom line is that there are three potential explanations for the low pressure readings:

(1) There are substantial leaks in the well;

(2) There is leakage in the sands deep under the seafloor. Oil industry professionals posting at the Oil Drum hypothesize:
What this could indicate is that there is a possibility of crossflow at the bottom of the well. What this means that the oil and gas that are flowing out of the reservoir into the bottom of the well, are, under the pressure in the well, now flowing into a higher reservoir of rock, now that they can't get out of the well. Depending on where that re-injection flow is, this may, or may not, suggest that the casing has lost integrity. This is a topic that has been covered in the comments at The Oil Drum, where fdoleza - "a petroleum engineering consultant retired from a major multi-national oil company" - has noted:

... I believe the flow will be coming out of the bottom sand and going into the upper sand. It would not be a leak, but it would tell them why their pressure data ain't a classical surface buildup. And I sure hope they're modeling temperatures and so on, because this is a very interesting case. They don't have downhole gauges, so they'll have to take the way the oil cools down as it sits to get a better idea of the way things are moving down below.

If there are questions whether there is still flow in the formation or from the original formation into surrounding rock, then it is possible that the relief well (RW) is close enough to the original well (WW) that putting a set of very sensitive microphones down the RW might allow some triangulation to estimate where such a flow might be occurring. It might make it easier that the well hasn’t been finally cased yet. But the test has 2 days to run, and will be evaluated every 6 hours. With time some of these questions may be answered as the test continues. (If there is no flow anywhere, after a while all the readings should become quite stable).

or

(3) The reservoir has been depleted more than engineers anticipated (although many experts have said that the reservoir is much bigger than BP has forecast; in any event, there are factors other than size which determine pressure. For example, blowouts can reduce pressure pretty quickly in some reservoirs)
While many oil industry experts are betting on damage to the well bore or communication between layers of sand, Don Van Nieuwenhuise - Director of the Professional Geoscience Programs at the University of Houston - thinks reservoir pressure has simply "deflated":

http://www.washingtonsblog.com/2010/07/pressure-test-failing-stopping-short-of.html

[StackerKen]

yeah well hopefully its # 3 :-\

[JohnQPublic]

yeah well hopefully obamafully its # 3 :-\


There. Fixed it for you! :)

(I do agree, by the way)

[cortez]

# 1.