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Is Drilling a Relief Well in Advance the Answer to Deepwater Blowout Risk?

by Michael Levi
June 18, 2010

There is a lot of buzz over Senator Frank Lautenberg’s suggestion that oil companies be required to drill a relief well at the same time as they drill any deepwater production well. That would allow the company to go in and plug any leak in relatively short order. Kate Mackenzie over at the FT Energy Source flags the most promiment objection, other than cost, as articulated by ExxonMobil CEO Rex Tillerson:

“Well I would say you just doubled your risk. This is an exploration well so it means you’re drilling in an area that’s not previously been drilled before. If you look at the history of well control problems and blowouts, most of them have occurred on the way down to the objective, not once they reach their objective. They’re caused by shallow gas hazards, they’re caused by unknown pore pressures on the way down to the objective, so if you have two wells going down at the same time it means you have just increase your risk of having a problem on the way down to them.”

I have two problems with this argument.

It is representative of a pre-Deepwater Horizon mentality that focuses entirely on the probability of a blowout and largely neglects the consequences of an event. It may make sense to accept a doubling of the (small) probability of a blowout if, at the same time, we can drastically reduce its consequences. Indeed politically, if deepwater drilling is to be maintained, the government will need to be able to explain how it will stop a blowout. Simply pointing to reduced odds of one won’t be enough. The pre-drilled relief well provides a means of answering that question.

My second problem is with the assumption that the two wells would need to be drilled simultaneously. That is the least-cost option, but it is not the only one. Drilling the two wells in sequence, rather than in parallel, would seem to substantially lower the odds of an accident with the second one, since the area would be much better known by the time that well was being drilled. It would, of course, be more expensive and time consuming. But that is the foundation for a cost-benefit analysis, not a reason to reject the option altogether.

My sense is that the big question is indeed cost, and, consequentially, the impact on production. Profit margins for deepwater production may or may not be high enough to absorb the extra cost without foregoing production. (There is also a cost-benefit question, but producers would do well to keep in mind that the politically realistic alternative to adopting expensive failsafe mechanisms may be seeing a huge amount of reserves put off limits completely.) I may do a back of the envelope calculation later to get a sense of how these numbers work. But this is something the EIA should be able to crank out. When it does, it should also look at the international impact. Other countries may well copy any new regulations that the United States imposes. The U.S. government should make sure that it anticipates the production consequences of such a move.

Post a Comment 3 Comments

  • Posted by Ken Capron

    It is a terribly human flaw to over-correct when something goes wrong. And it is commonly human to err.

    If the cause of this blowout turns out to be bad behavior of human origin, relief wells won’t solve a thing. It may indeed delay the inevitable that some other human may make a similarly bad judgment call. But there is no cure for being human.

  • Posted by John Galt

    Either the author doens’t understand the objection, or I don’t. My understanding of the Tillerson comment is that the blowout occurs before the two wells connect with each other. The second well is then of no use controlling the blowout of the other. I also don’t understand the comment about drilling them in series, isn’t that what we’re doing right now in the Gulf?

  • Posted by Sean O'Boyle

    The assertion that drilling a relief well pre-necessity is a risky venture unto itself whilst drilling an exploratory well is indeed a valid statement/concern. In preparation for drilling an exploratory well (EW) an earth model is created based on some seismic, some generally accepted calculations and generalized interpretations by geophyical/technical personnel. These “guesses” are only proved right or wrong after the sedimentation is penetrated. Therefore it could be extremely risky to simply drill another well into this same relatively unknown area. Now the idea of drilling a well sometime after the initial well has started presents a whole host of other problems (some of them commercial, i.e. the rigs used are typically scarce quantities so simply demanding another rig may not prove to be viable)- what if the primary well has problems, what if the secondary well drills faster, at what angle do you drill, if you have a blow out can the second rig stay on location or would it need to move off, could you drill into a subsurface hazard with the second well? I’m not advocating abandoning the idea of being prepared for relief well capabilities. In fact I think the industry has done a poor job of being prepared (if this incident had happened to a company not drilling several other prospects the ability to secure another capable rig quickly may not be a viable option- despite companies best intentions) to drill a relief well in deepwater. On the contrary particular efforts need to be made to improve recovery measures, enforce existing regulations and improve the quality of oversight (i.e. most of the industry insiders typically mock the MMS staff as being less than capable- in fact they do have bright capable staff but to be honest they don’t have enough manpower to really do their job). In the end, simply saying all wells should have concurrent relief wells drilled is not a viable solution- a good discussion topic & perhaps required on specific high risk operations – but not a final risk free solution.

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