An interesting read from The Oil Drum on what happened to cause this disaster.
What caused the Deepwater Horizon disaster?
Author’s Note: I am grateful to the many drilling and completion engineers that consulted with me on this post to arrive at plausible explanations and interpretations of what happened in the final hours on the semisubmersible drilling rig Deepwater Horizon in the Gulf of Mexico. The analysis that follows is based on these discussions as well as my own 32 years of experience as a geologist working in the oil and gas industry.
It is early in the process of discovering what really happened. Because of the gravity and potential impact of this disaster on the nation and my industry, however, I wanted to provide an early and more investigative perspective than much of what has appeared in the media to date. The risk, of course, is that more information will invalidate some of what follows. I, therefore, wish to clarify that this is a fact-based interpretation of what may have happened on the Deepwater Horizon on April 20, 2010 but, in the end, it is an interpretation. – Art Berman
The blowout and oil spill on the Deepwater Horizon in the Gulf of Mexico was caused by a flawed well plan that did not include enough cement between the 7-inch production casing and the 9 7/8-inch protection casing. The presumed blowout preventer (BOP) failure is an important but secondary issue. Although the resulting oil spill has potentially grave environmental implications, recent efforts to limit the flow with an insertion tube have apparently been effective. Continuous efforts to slow or stop the flow include drilling two nearby relief wells that may intersect the MC 252 wellbore within 60-90 days.
You can read the whole article here.
Source: The Oil Drum