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Posts Tagged ‘well integrity test’

In the Gulf of Mexico, deepwater drilling is more risky because that is where the high-rate wells are, not because the water is deep.
  • Water depth had little to do with the well integrity problems at Macondo. Similar errors in planning and execution would have yielded similar results in any water depth or on land.  Has Montara already been forgotten?
  • Subsea BOP stacks have a much better performance record than the surface stacks used in shallow water drilling (more on this later in the week).
  • Historical data indicate that blowouts occur less frequently in deep water, not more frequently (more to follow).
  • Obviously, blowouts involving high-rate wells are likely to do more damage.   This applies regardless of the water depth.   You can reduce the spill risk by prohibiting drilling in the areas with the highest production potential, but that wouldn’t be very sound energy policy and you won’t find many buyers for the leases.
  • It is safer to conduct intervention and capping operations on subsea wells.  Regulators would not even allow surface capping to be considered at Montara because of the high risk to workers.  The subsurface ROV work is perhaps the biggest Macondo success story.
  • If the Macondo well was in shallow water (with the wellhead above the water surface), and well integrity concerns precluded a risky surface capping operation, how would the flow have been contained and collected?
  • Other things being equal, the environmental risk is less at deepwater locations which tend to be farther from shore.

Water depth is just one well planning consideration.  Abnormal pressures and temperatures, shallow gas, hydrogen sulfide, ice, permafrost, storms, currents, extended reach targets, and horizontal completions are some of the others.  To prevent another Macondo, in the US or anywhere else in the world, we need to focus our attention on the 3 categories of issues listed below.  These issues are important in all water depths and in all environments.

  1. Well integrity including design, construction, barriers, verification, and monitoring.
  2. BOPE performance and reliability under all conditions.
  3. Capping, containing, and collecting oil in the event of a blowout.

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Statement by Admiral Allen this morning (19 July):

I authorized BP to continue the integrity test for another 24 hours and I restated our firm position that this test will only continue if they continue to meet their obligations to rigorously monitor for any signs that this test could worsen the overall situation.

Comments: 

  • Interesting wording.  Why imply that shutting-in the well is some type of special favor to BP?  One would think that BP would be directed (not allowed) to keep the well shut-in. 
  • I have seen no reason for discontinuing the “test.”  The reported gas observation could be a natural seep of which there are hundreds in the deepwater Gulf.  Even if there is minor gas seepage associated with near surface well integrity issues, this seepage will end when the source (the Macondo reservoir) is killed.  It is extremely unlikely that shutting in the Macondo well would create new channels (not associated with the well bore) all the way from the reservoir back to the seafloor. 
  • I thought last night’s leak about a leak was interesting.  Was the press leak intentional? Who was the leaker intending to embarass?  BP?  The Unified Command?  Admiral Allen?  Strange.

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Capping Stack BOP onboard the Transocean Discoverer Inspiration close to the MC252 location 7 July 2010.

Capping Stack BOP Before Installation on Well

Here we go ……

  1. Close rams to shut-in flow from the top while allowing flow through choke and kill lines on sides of capping stack.
  2. Slowly close kill line.
  3. Slowly close choke line.
  4. If the pressure holds through all 3 steps, Secretary Chu does a touchdown dance in the BP control room (BOE exclusive :))

Other:

  1. Operation will be halted every 6 hours to monitor pressure;
  2. Ongoing ROV monitoring of well and seafloor;
  3. Remote sensing systems looking for evidence of leakage outside the wellbore;
  4. Up to a 48 hour process

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Today I met with Secretary Chu, Marcia McNutt and other scientists and geologists as well as officials from BP and other industry representatives as we continue to prepare and review protocols for the well integrity test – including the seismic mapping run that was made around the well site this morning. As a result of these discussions, we decided that the process may benefit from additional analysis that will be performed tonight and tomorrow. ~ Admiral Allen

This well integrity test delay is probably reasonable and prudent, but one does wonder about the number of scientists involved, and whether the seismic data interpretations are sufficiently accurate to reliably assess fracturing and channeling risks.   

At this point, you could argue that a complete shut-in is not necessary.  However, the test probably still makes sense for the purpose of gathering useful well integrity data before the relief well hits its target, and for determining whether the well could be shut-in during a lenghty hurricane evacuation.

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