Crystals, the Gulf of Mexico Blowout, and the new 'Top Hat' Dome

The situation in the Gulf, in regard to the Deepwater Horizon fire and oil spill continues to evolve. Since my last post on this, the size of the operation has continued to grow, with some thought now being given to dredging barriers along the coastline. What I thought I cover a little today, among other things, is the problems that occur when oil leaves a hot reservoir and suddenly enters a pipe on the floor of a very cold sea, causing some of the constituent chemicals to crystallize out. To illustrate this, I took a picture of one of the pipes that used to sit in my office, since it helped visualize a problem we had been given, and is along the lines of that now facing BP.

You will note that the crystals have reduced the effective diameter of the pipe down to about 1.5 inches, cutting the flow the pipe can carry by 75% (roughly). These are but one example of a number of different chemicals that can precipitate out in the pipes that carry oil from the reservoir, where it is hot, up through colder zones as it rises through the different pipes on its way to land. There are two different aspects to the problem that I want to cover since it relates to the formation of methane hydrates in the capture box that BP had fielded at the end of last week.



The first of these is on the growth of the crystal hydrates within the confinement box that BP had lowered over the middle leak in the riser. However, rather than dig back into my notes, I am going to suggest that those who want to understand the chemistry/physics go to The Obligate Scientist. He uses a plot from the USGS to illustrate the conditions that transition methane gas to methane hydrate as a function of temperature and pressure (depth in the ocean).

Keeping deposits from clogging feed lines is thus a tad more complicated than it may first appear. And while I note that BP is now apparently planning on lowering a second smaller cap into position, there may need to be other modifications (such as an inner liner of Teflon to insulate the flow from the radiative metal of the box) that have been added (perhaps an internal heating system) to help alleviate the problem.

The Unified Command Center has noted the following update to the resources mobilized to help with the spill:

Total response vessels: more than 290

Boom deployed: more than 1.1 million feet (regular plus sorbent boom)

Boom available: more than 1.4 million feet (regular plus sorbent boom)

Oily water recovered: approximately 3.6 million gallons

Dispersant used: approximately 372,000 gallons

Dispersant available: approximately 180,000 gallons

Overall personnel responding: approximately 10,000

http://www.theoildrum.com/node/6458

if there isn't some sort of cracking process going on. The oil hitting the cold water at high pressure might stratify into the light stuff which comes to the surface and a heavy component that stays deep. Since temperature and pressure effect density we might have a huge blob moving around at a few thousand feet below the surface.

surface.

nt