2008
March 2008 – The mineral rights to drill for oil at the Macondo well, located in Mississippi Canyon Block 252 in the United States sector of the Gulf of Mexico about 41 miles (66 km) off the Louisiana coast, were purchased by BP at the Minerals Management Service's (MMS) Lease Sale No. 206, held in New Orleans.[6]
2009
February – BP files a 52 page exploration and environmental impact plan for the Macondo well with the MMS. The plan stated that it was "unlikely that an accidental surface or subsurface oil spill would occur from the proposed activities".[7] In the event an accident did take place the plan stated that due to the well being 48 miles (77 km) from shore and the response capabilities that would be implemented, no significant adverse impacts would be expected.[7]
April 6 – The Department of the Interior exempted BP's Gulf of Mexico drilling operation from a detailed environmental impact study after concluding that a massive oil spill was unlikely.[8][9]
June 22 – Mark E. Hafle, a senior drilling engineer at BP, warns that the metal casing for the blowout preventer might collapse under high pressure.[10]
October 7 – The Transocean Marianas semi-submersible rig begins drilling the Macondo well.[11]
November 9 – Hurricane Ida damages Transocean Marianas enough that it has to be replaced.[11]
2010
February
February 15, 2010 – Deepwater Horizon drilling rig, owned by Transocean, begins drilling on the Macondo Prospect.[11][12][13][14] The planned well was to be drilled to 18,000 feet (5,500 m) below sea level, and was to be plugged and suspended for subsequent completion as a subsea producer.[15]
March
March 8 – Target date for the completion of the well which had been budgeted to cost $96 million.[11]
March 17 – BP Chief Tony Hayward sells one third of his BP stock (223,288 shares).[16] Closing BP price on March 17 on the New York Stock Exchange is 58.15.
March – An accident damages a gasket on the blowout preventer on the rig.[10]
April
Fighting the fire on April 21
April 1 – Halliburton employee Marvin Volek warns that BP's use of cement "was against our best practices."[10]
April 6 – MMS issues permit to BP for the well with the notation, "Exercise caution while drilling due to indications of shallow gas and possible water flow."[17]
April 9 – BP drills last section with the wellbore 18,360 feet (5,600 m) below sea level but the last 1,192 feet (363 m) need casing. Halliburton recommends liner/tieback casing that will provide 4 redundant barriers to flow. BP chooses to do a single liner with fewer barriers that is faster to install and cheaper ($7 to $10 million).[11]
April 9 – Halliburton agrees to buy Boots & Coots, a company that provides pressure control services for oil and gas wells, for about $240 million worth of cash and stocks. The deal will be accretive in the first full year of operation, Halliburton said. The second largest oilfield services company will create a new product service line combining its existing coiled tubing and hydraulic workover operations with Boots & Coots' intervention services and its pressure control business.
http://www.reuters.com/article/idUSTRE63907A20100410
April 14 – Brian Morel, a BP drilling engineer, emails a colleague "this has been a nightmare well which has everyone all over the place."[11]
April 15 – Morel informs Halliburton executive Jesse Gagliano that they plan to use 6 centralizers. Gagliano says they should use 21. Morel replies in an email, "it's too late to get any more product on the rig, our only option is to rearrange placement of these centralizers." Gagliano also recommends to circulate the drilling mud from the bottom of the well all the way up to the surface to remove air pockets and debris which can contaminate the cement, saying in an email, "at least circulate one bottoms up on the well before doing a cement job." Despite this recommendation, BP cycles only 261 barrels (41.5 m3) of mud, a fraction of the total mud used in the well.[11]
April 15 – MMS approves amended permit for BP to use a single liner with fewer barriers.[11]
April 16 – Brett Cocales, BP's Operations Drilling Engineer, emails Morel confirming the 6 centralizer approach.
April 17 – Deepwater Horizon completes its drilling and the well is being prepared to be cemented so that another rig will retrieve the oil. The blowout preventer is tested and found to be "functional."[18] Gagliano now reports that using only 6 centralizers "would likely produce channeling and a failure of the cement job."[11]
April 18 – Gagliano's report says "well is considered to have a severe gas flow problem." Schlumberger flies a crew to conduct a cement bond log to determine whether the cement has bonded to the casing and surrounding formations. It is required in rules.[10][11]
April 19 – Halliburton completes cementing of the final production casing string.[19]
April 20 –
7 am – BP cancels a recommended cement bond log test. Conducting the test would have taken 9–12 hours and $128,000. By canceling the cement test BP paid only $10,000. Crew leaves on 11:15 am flight.[11] BP officials gather on the platform to celebrate seven years without an injury on the rig.[20] The planned moving of the Deepwater Horizon to another location was 43 days past due and the delay had cost BP $21 million.[21]
April 20, 2010 21:49 (CDT), Block 252, Mississippi Canyon Andrea Fleyras had been monitoring the dynamic positioning system on the bridge of the Horizon when she felt a jolt. Before she could make sense of it – a rig shaking shock that came out of nowhere – magenta warnings began flashing on her screen. Magenta meant the most dangerous level of combustible gas intrusion.[22]
9:45 pm CDT – Gas, oil and concrete from the Deepwater Horizon explode up the wellbore onto the deck and then catches fire. The explosion kills 11 platform workers and injures 17 others; another 98 people survive without serious physical injury.[23]