Monday, June 14, 2010
HOW TO CRACK THE EARTH
By : Isaac
Several stories are circulating about sub-floor damage and explosions..Here's what I think. Drilling mud with an ambient temperature of the surrounding deep sea, 39 degrees F, was pumped with 50,000 horsepower into a 35,000 foot deep borehole in an area with massive irregular salt formations close to an underground lava flow.. " Top kill " is normally called " Bullheading " This is the most common method of a contingency well kill. If there is a sudden need to kill a well quickly, without the time for rigging up for circulation, the more blunt instrument of bullheading may be used. This involves simply pumping the kill fluid directly down the well
bore, forcing the well bore fluids back into the reservoir. This can be effective at achieving the central aim of a well kill; building up a sufficient hydrostatic head in the well bore. However, it can risk damaging the reservoir, by forcing undesired materials into it. The principal advantage is that it can be done with little advanced planning.
Not smart in this situation at all. why ?
The type of drilling mud containing water that they used for Top Kill..
Water-based mud (WBM): A most basic water-based mud system begins with water, then clays and other chemicals are incorporated into the water to create a homogenous blend resembling something between chocolate milk and a malt (depending on viscosity). The clay (called "shale" in its rock form) is usually a combination of native clays that are dissolved into the fluid while drilling, or specific types of clay that are processed and sold as additives for the WBM system. The most common of these is bentonite, frequently referred to in the oilfield as "gel". Gel likely makes reference to the fact that while the fluid is being pumped, it can be very thin and free-flowing (like chocolate milk), though when pumping is stopped, the static fluid builds a "gel" structure that resists flow. When an adequate pumping force is applied to "break the gel", flow resumes and the fluid returns to its previously free-flowing state. Many other chemicals (e.g. potassium formate) are added to a WBM system to achieve various effects, including: viscosity control, shale stability, enhance drilling rate of penetration, cooling and lubricating of equipment. But the well casing is also broken in several places allowing mud to leak out..
So there's the cold water entering the surrounding sub-floor, it's contained in the drilling mud., then..
There are the effects of rapid expansion of water flashing to steam. Water expands to almost 1700 times its original volume within a few microseconds. There is also the fact that water can become super-critical at temperatures greater than little over 700 degrees f. Which is a moot point except when we examine the fact that an increase in salinity lowers boiling point of water .What does this have to do with anything ? Well, the area that they are working in is a massive salt ridge is slightly pertinent.
In addition, close to the critical point, small changes in pressure or temperature result in large changes in density,Which is easily to fairly easy to predict.....if you know the salinity saturation of the water. Of course, when it's constantly fluctuating, it's hard to plan ahead.
The detonation of an explosive charge underwater , or, like in ' Top Kill " extremely high-pressure steam explosions, results in an initial high-velocity shockwave through the water, in movement or displacement of the water itself and/or substrata in the formation of a high-pressure bubble of high-temperature gas. This bubble expands rapidly until it either vents to the surface or until its internal pressure is exceeded by that of the water surrounding it. (The volumetric expansion of the bubble also leads to a drop in internal temperature in accordance with Charles’ Law.) At this point, as noted above, the over-expanded bubble collapses into itself, leading again to a rise in bubble pressure and internal temperature until such time as the bubble pressure exceeds water pressure. The bubble again expands, although to a rather smaller size. A second shockwave is produced by this expansion, although it will be less intense and of rather greater duration than the first. With each cycle, the bubble moves upwards until it eventually vents or dissipates into a mass of smaller bubbles.
If you are familiar with cavitation, or methane cavitation, you are well aware of the dangers presented by Top Kill.
This combined with the widening cracks being sandblasted through the sub-floor, and the 5k feet of cold water beginning to force it's way in, is possibly going to cause a runaway collapse.