BP and the relief well drilling

Factual Questions
1

My question pertains to the relief well that is being drilled and if it is something that is going to be done regardless of the hole being plugged or not.

The reason I ask is because I wonder what would happen if the hole had been plugged. Would the relief well still be drilled? If the answer is “Yes, they would still have to drill the relief well” then my question is irrelevant.

If the answer is “No. If the hole had been plugged then the well would not be drilled”… Well then that’s a different story.

It makes me wonder if BP thinks "Hmm, if we plug the hole then we can’t drill another well there and keep pumping oil from it. If the hole doesn’t get plugged, and drilling is banned, except for the releif well, then we can drill it and still recover the oil.

If there isn’t a factual answer to this then please just close it because I am just curious and don’t care to debate what I think may be some nefarious goals from BP.

2

Yes, plugging the hole from the top was always temporary - damage limitation.

The bottom kill is the only way to ensure the dead well is capped permanently.

Either way, the reservoir itself can still be recovered by drilling a completely new well.

3

Well if you’re saying the relief well was inevitable then that answers my question. But if drilling is banned for now then they wouldn’t be able to to recover anything else from the reservoir because of the ban if the leak were plugged.

4

That’s true, but offshore drilling isn’t banned now (there’s a temporary moratorium) and it won’t be banned in the future. Once the regulatory authorities get their shit in gear and the relevant congress critters are satisfied, a new well will be drilled and everyone will be farting rainbows and unicorns again.

5

In Canada they actually build the wells before the oil spill.

6

If you mean the releif wells are drilled in advance of the actual wells, as has been suggested by US Federal agents, that doesn’t happen in Canada according to your link and it doesn’t happen anywhere for good reason. As T. Boone Pickens told Larry King recently, a relief well is just a second well, if you drill it in advance it would carry the same risks as the original well. Pickens also mentioned something that you probably don’t want to hear - there is no guarantee the long awaited relief well will actually succeed in stemming the flow.

7

I am unclear on exactly how the relief well will stop the flow. To make a simple analogy, if you poke a hole in a garden hose, some water will come out of the hole, but water will still be flowing out the end. How is drilling a second hole supposed to stop the flow out of the first hole completely?

8

"A drilling rig drills a relief well or second well to intersect the original, flowing well as deeply as possible. A specialized heavy liquid is then pumped into the flowing well to bring it under control. This liquid is denser than oil and so exerts pressure (known as hydrostatic pressure) to stem the flow of oil. Once the flow is stopped, the well can be returned to a safe condition. "

http://www.bp.com/genericarticle.do?categoryId=9033657&contentId=7061734

9

The problem is getting enough pressure, and a bottom kill is the solution to that problem:

The well casing is carrying the tremendous pressure caused by the weight of 10,000 feet of rock/whatever + 5000’ of seawater -10,000 feet of oil, up to where there is only 5000’ of sea water providing pressure. * The pressure at the bottom of the well can only be as great as the weight of the stuff above it…otherwise it would lift that stuff up (and it does) and relieve the excess pressure.

Note the minus sign on the oil term. If you can replace the oil with something as (or more) dense as the rock/whatever then the pressure difference drops to zero by the time you get up to the top of the well. That something heavy is drilling mud. Mud controls the pressure with it’s weight, NOT because it is viscous. The viscosity helps keep oil from mixing with it, but that is about the only benefit.

It is a tremendous problem to try to get the mud down into the top of the well while oil is spewing upward. This is why the top-kill attempt failed. Imagine trying to stop up a garden hose with hand fulls of sand while the water is spewing out.

When you drill the relief well, the relief well is filled with heavy mud. You break into the damaged well well down the oil column, ideally right at the bottom. You pump in mud, and it flows upward and downward. As it flows upward, the head at the bottom increases to the point that the flow stops…the damaged well has been successfully bottom killed. Instead of trying to pour sand into your garden hose, you are dumping sand into the elevated tank that supplies the water to the hose…dump enough sand in that tank, and you will totally plug up the city water system with sand.

This not only can work, it almost certainly will. The realistic concern is missing the damaged well with the relief wells. They use magnetic sensors down-hole to try find their way to the damaged well. Hopefully these sensors are better performing than the blow-out-preventer. (actually, it is sounding like the BOP would have still worked if BP hadn’t cheaped out and taken the mud out of the well prematurely)

They are drilling two relief wells so that they have a second shot if they miss the first time. If they both connect, they have some redundancy, and can pump mud in faster.
*I omitted the 100 miles or so of air at the top of the stack…this adds 15 psi or so…about as much as adding another 32’ of water…not really important in the scheme of this crisis.

10

Well there goes my conspiracy theory. Thanks all!

11

Thanks for the theory, you made my brain rollover one more time. If you want a fun conspiracy theory, T Boone Pickens has been supporting BP on Larry King, but he has BP in his initials, he probably owns most of the BP shares.

You do know almost twice as many US Citizens are employed by BP than are employed in Britain? And that BP pays far more US than UK tax? From the outside, it looks like Obama is in a jam. He permitted this sort of drilling to get his environmental legislation through, without judging the risk accurately, and so now he will play to the crowd. It’s not edifying. He knows the worst is yet to come. Even when the relief well is drilled, the drill ship can only process 18,000 barrels a day, so any more than that will be burnt off with the gas. That isn’t great for the environment either.

12

He lifted the moratorium (as you say probably as a compromise to pass through environmental legislation), but drilling still would not have started for another year or two -allowing him time to reenact the moratorium if he wanted to.

Further, the permits for BP to drill in the Gulf were given under the Bush administration. Obama has been working from the start to reform the corrupted EPA and MMS, who share responsibility for the spill.

Just wanted to give that quote some more context…

13

Here’s what Tudor Pickering had to say about the relief well process this morning.

[QUOTE=Tudor Pickering]

· Relief wells – As the Macondo containment attempts have had limited success in reducing the oil flow, there has been more talk concerning relief wells. Moreover, many are skeptical that the relief wells will be successful in stopping the Macondo blowout. Although BP has not provided much detail on the relief well operations, we are highly confident that the relief well(s) will be successful, and the major uncertainty is timing (not “if” but “when”) the relief well(s) will successfully penetrate and kill the Macondo well.

· Status of current relief wells? Both relief wells are targeting 18,000’ and the first relief well has reached 13,978’ and the second relief well is at 9,022’. BP still expects both wells to take 3 months from initial spud date….so still targeting early August assuming no major operational or tropical weather delays.

· Why two relief wells? Simple answer…Insurance. Drilling a deepwater well to 18,000ft takes time and drilling operations can encounter unplanned events that slow down/delay drilling. Two wells increases the odds that one of the wells can be drilled rapidly…with fewer delays and ultimately less spill oil.

· Relief well plans? BP plans for the relief well to intersect the Macondo well at 18,000ft and pump heavy weight drilling mud into the wellbore to stop the flow (link). They suggest August as their expected case for relief well intersection. A number of questions have arisen:

o Why 18,000ft and not shallower? True, a shallower well could be drilled more quickly, but the odds of a successful kill decrease in a shallow intersection.

· A shallower well would require penetrating multiple casing strings increasing the potential risks (the original Macondo well has nine separate casing/liner strings).

· A low penetration is optimal in a “dynamic kill”. It increases the chance that pumping heavy mud will control the Macondo well. Remember the top kill did not work as the injection rate could not overcome the well flow…same result could happen if the relief well intersected shallow. The dynamic kill is designed to pump heavy weight drilling mud in the lower portion of the well and fills it “bottoms ups”, until the weight of the fluid column in the well is greater than the formation pressure…ceasing the flow.

o Needle in the haystack? Not really. We have heard many skeptics of the relief well suggest that intersecting the Macondo well is the equivalent of finding a needle in a haystack.

· We disagree. It is like finding a needle in haystack…when you know roughly which part of the haystack the needle is in and employing high-tech detection equipment.

· Remember the Macondo well has metal casing (pipe) all the way to the bottom of the well. The relief wells will employ sensors to detect the existing casing (likely magnetic and/or conductivity measurement tools) to determine the proximity of the relief well to the blowout. It is unlikely that the relief well will intersect Macondo on the first try. But BP will be able to eventually narrow in on the relief well and,via a series if sidetracks, ultimately intersect and control the well. Hopefully this process wont resemble the way Pursell putts (a series of spastic over-corrections)….but does illustrate the reason we believe the relief well is a “when” not “if” proposition.

· What we don’t know? What type of directional surveys are available in the Macondo well (i.e, how accurately does BP know the position of the existing wellbore)? We assume directional measurements were taking during drilling operations but are not sure if a post casing gyro-survey was run (we think not but have not been able to verify).

· Risks

o Timing – as we previously mentioned, it may take several passes to actually intersect to Macondo well. Last year, a relief well to kill the Mantara blowout in Australia took five passes. Ugh. Delays in the intermediate hole due to normal drilling issues, difficulty “finding” the Macondo well, coupled with active tropical weather in the GOM (requiring relief well drilling ops to be suspended) that could push a successful relief well to the end of the year. We think base case is August/Sept with bias being longer not shorter.

o “Dynamic Kill” – Although we assign a 99+% probability of success to the relief wells, relief wells are not foolproof. A relief well in Tengratila Bangladesh experienced a blowout in 2005. Specifically, the Macondo well experienced a strong gas kick in a shallow zone which the relief wells will have to penetrate. Moreover, BP can’t be too aggressive with the dynamic kill. The high mud weight (14.4ppg) required to control the pressure at 18,000ft is only slightly below the mud weight of ~16ppg (our guess) that could induce fractures (this is no bueno when one is trying to control a hydrocarbon inflow). The kill weight fluid and pump rate will have to be carefully monitored to avoid “breaking down” (fracturing) the formation. Not insurmountable, but deepwater operations narrow the margin for error.

o Not new technology - Finally, we have lots of confidence as relief wells are “not new technology”. Relief wells are widely accepted as the most effective way to control a blowout. For example, in 1982 TXO drilled a 13,000ft relief well to control a blowout in East Texas which at the time was the second deepest relief well ever drilled with a wellbore intercept (ref SPE paper #18059). A study of this well concluded that “For the first time in the history of the industry, relief wells are a viable and reliable alternative in well control operations”. In the intervening 28 years, the technology and success have steadily improved. 99+% chance…not “if” but “when”.
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