The MC 252 well is located in 5,067 ft of water about 50 miles from the coast of Louisiana. Two days later, the Deepwater Horizon sank to the bottom of the Gulf of Mexico, and oil has been spilling into the Gulf at rates of at least 5,000 barrels per day since then(there are 42 gallons in a barrel). This all happened so fast that those who died probably had no time to understand what was happening. Eleven men died instantly and 115 others rushed to the lifeboats or jumped into the Gulf of Mexico. A second explosion followed and the electricity went out. The gas exploded and the rig was engulfed in flames. At about 10:00 p.m., the rig unexpectedly began to shake and a loud surging noise was accompanied by natural gas, drilling mud and sea water that shot high above the floor of the drill ship. In a few hours, they would have been ready to move the drilling rig off location so that a completion rig could move on. On April 20, 2010, the crew of the Deepwater Horizon was preparing to temporarily abandon BP’s “Macondo” discovery well in Mississippi Canyon (MC) Block 252 (Figure 1). 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. Although the resulting oil spill has potentially grave environmental implications, recent efforts to limit the flow with an insertion tube have apparently been effective. The presumed blowout preventer (BOP) failure is an important but secondary issue. 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. I, therefore, wish to clarify that this is a fact-based interpretation of what may have happened on the Deepwater Horizon on Apbut, in the end, it is an interpretation. The risk, of course, is that more information will invalidate some of what follows. 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. It is early in the process of discovering what really happened. 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. 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.

Deepwater horizon cast