Plausible Oil Spill Scenario: Underground Blowout and Mudflow

By Dian L. Chu, Economic Forecasts & Opinions

Amid rising fears over a circulating story about a leak and seepage, the federal government's oil spill chief said that seepage detected two miles from BP's oil cap is coming from another well. Meanwhile, BP is on track to use static top kill procedure in Macondo.

The static kill option is basically the cousin of the previously failed top kill. According to Platts, “the static kill would pump drilling mud and cement into the well, using the same entry points as the previous top kill procedure. The materials would be forced into the choke and kill lines of the well's blowout preventer (BOP).”

Scenario Apocalypse?

Although BP's new containment cap has stopped the flow of oil, circulating stories about a leak and seepage had caused mounting concern that the cap was displacing pressure and causing leaks deep underground.

One oil industry veteran engineer describes to me an underwater blowout (UGBO) as quite plausible, with the well being capped plus the static kill adding pressure from the top.

That is, capping the well might not be such good news.

The more they try to restrict the oil gush, the more pressure could be built up within the wellbore (like a soda can.) The increasing pressure could eventually push the leak below leading to a UGBO.  (See graph)

(Note: The graph is a general illustration and does not represent the BP Macondo well. Source: http://www.silentpcreview.com/)

What Is A UGBO?

According to Schlumberger Oilfield Glossary and Wikipedia:

“An underground blowout is a special situation where the uncontrolled fluid flows from one reservoir into the wellbore, along the wellbore, and into another reservoir. Usually this is from deeper higher pressure zones to shallower lower pressure formations.”

“Underground blowouts can be very difficult to bring under control, and are historically the most expensive problem in the drilling arena. If left unchecked the fluids may find their way to the surface or ocean floor nearby.”

While there are sporadic discussions around a possible UGBO at Macondo well, it is still hard to visualize what kind of damage it could actually bring. A look at the ongoing mudflow environmental disaster in Indonesia could shed some light.

Indonesia Mudflow

The Sidoarjo mudflow in east Java, Indonesia has been ongoing since May 2006. The mud volcano was created by the blowout of an exploration well drilled by PT Lapindo Brantas, which triggered the eruption of hot mud.

The hot mud has continued to spew out at a rate of 100,000 cubic meters a day--equivalent to the contents of forty Olympic-size swimming pools--despite government efforts to plug the leak.

News reports described the mud lake is so huge — seven square kilometers in area and 20 meters deep — that it is now visible from space. Experts have warned that the mud may continue to flow for several decades.

Since 2006, the mudflow ha s inundated hundreds of hectares while new mudflows are still opening up. Some 50,000 Indonesians reportedly have been displaced after the drilling accident in May 2006.

Mudflow in the Gulf?

In the case of the Macondo well, a UGBO could cause a seismic shift of the seafloor, and a potential astronomical increase of oil shooting to the sea surface of the Gulf, and flowing towards coastline. The seabed breach could also bring about a mud volcano and mudflow, similar to what happened in Indonesia, in the Gulf of Mexico deepwater, possibly for decades.

In fact, this is the very same doomsday scenario many scientists and geologists have feared, as there are some early signs of a typical UGBO such as the reported seepage and leak. That is why BP and the U.S. government have been feverishly analyzing underwater data and monitoring the pressure.

This one oil industry expert I talked to believes that with the failure of the first top kill, and the risk of UGBO, the more prudent course is to just drill the two relief wells as planned (see graph), instead of further risking the well integrity by the trying experimental well cap and another static kill.

Graphic Source: WSJ

Inaction Is Good …., Occasionally?

While this apocalyptic scenario seems beyond the imaginable, and there does not seem to be a previously documented case of a deepwater UGBO, but again, everything regarding this gulf disaster has been unprecedented.

I imagine all the experts in BP’s camp are quite aware that the risk of an UGBO is quite high, but with mounting public criticism towards BP and the Administration, any cautionary (i.e., non-action) note most likely will not be taken into serious consideration by the people in charge.

Crucial - Implementing Lessons learned 

There are plenty of lessons learned and yet to be acted upon for the spill response and remedial side of the oilfield technology to catch up with the technology on the drilling and production side. The new rapid response system for the Gulf deepwater announced by the four oil majors--Chevron, ConocoPhillips, ExxonMobil and Shell-- seems to be a good start towards that direction.

Meanwhile, let’s hope a deepwater UGBO remains as a scenario-based discussion only.

(Many thanks to the silent co-contributor of this article.)

Dian L. Chu, July 25, 2010

Comments

[titatu]

a nice link with some videos about oilspill:

http://www.projectgulfimpact.org/showreel/

[titatu]

Suggestion for commenters:

Why not to go for a while to Siberia, join the party?

It saves me a lot of time reading dumb suggestions.

Take some friends with or go to Indonesia, have a nice break, top holiday, do some surfing etc and get refreshed? investigated on the spot, what undersea vulcanos can do.

[Jim_Rockford]

I think the top illustration in the article above is not reality based as it does not show the redundant casing and concrete that exists at the shallower depths of the well bore.  I am on a slow connection and cannot pull up the casing schematics but I think that there are multiple diameters of casing that run quite deep.  Also, my understanding is that the concrete plug will be injected via the relief well at or near 18,000 ft depth.  The scenario as laid out in the article above does not seem plausible to me, or perhaps I should say probable.

[asiablues]

Plausible or maybe probable scenario.  I've not seen a UGBO article describe what the damage could be and thought to explore that.  I noted that the first illustration is not of the BP well. 

[Jim_Rockford]

I'm confused ... is it Mcondo or Macondo in the article?  I see it spelled both ways.  I'm fear that some ZH'rs will take it as further proof of the second well scenario.

[asiablues]

typo, the article talked about only one well.

[Mr Lennon Hendrix]

Peak oil in the fact that we are trying to justify searching every corner of earth (including water) to find the stuff.

[asiablues]

Blame it on Matt Simmons then, since he is a leading peak oil theorist for many years.    

[Mr Lennon Hendrix]

Oh but peak oil is all of our faults.  Not believing nor considering that such is finite was a costly mistake!  Never-never-land, be it, was a dream!

[Broken_Trades]

interesting well in indo.

http://www.rigzone.com/news/article.asp?a_id=32618

Actual well facts from Indo... even more interesting.

http://www.searchanddiscovery.net/documents/2009/50186sawolo/index.htm

Several writers suggested that an Underground blowout triggered LUSI (Davies et.al, 2007; Tingay et al., 2008). However, the facts and pressure calculations clearly show that an underground blowout did not happen in the Banjarpanji-1 well. Several conditions must be met for an underground blowout to occur. The most important is that pressure in the wellbore must be sufficiently high to break the weakest formation (typically the casing shoe). Secondly, sustained fracture propagation pressure is required to extend the fracture to surface. Davies et al. (2007) suggested that the casing shoe was fractured and breached. However, calculations based on proper data obtained from the well and related facts clearly show the opposite; the shoe was still intact and not breached.

An investigation was carried out to determine if there was a connection between the well and the mud eruption. If an underground blowout did occur, then it was expected that a temperature anomaly and noise would be recorded in the Banjarpanji-1 wellbore. Temperature and Sonan logging were carried out during the relief well campaign to determine if such phenomena occurred. The temperature logs did not record any anomaly within the Banjarpanji-1 well (Figure 1). The sonan log did not indicate any unusual noise, indicating there was no flow behind casing (Figure 2).

Mud volcanoes are a common occurance in Indonesia.  This could be a coincidence and there is oodles of data to suggest that the well did not* cause an UGBO.

If there was a giant oil volcano erupting 200 m from the macondo well, I think it would be safe to say that its related to the drilling as oil volcanoes dont happen there evryday.

[taraxias]

What you neglected to mention is that the authors of this paper have been sucking at the tit of Big Oil for many years, collectively receiving over $3 million in funding over a 5 year time frame. The term "captured" comes to mind.

Why do you think BP is attempting to buy the silence of every top scientist on the planet?

What's next, oil gushing at 100,000 barrels per day is a naturally occurring phenomenon in the GoM?