BP took shortcuts which may have compromised the integrity of the well.
"1. A cement bond log was not run......to evaluate the effectiveness of the cement job. Slumberger was on site to run the cement bond log but BP decided not to run one, presumably to save the 12 hours it would take to run it. Pressure tests were run instead, but were inconclusive.
2. A lockdown sleeve was not used in the wellhead seal assembly for the production casing. This could cause the seal to unseat if there is upward movement of the casing, allowing fluid to enter the riser.
3. Only 261 bbl of mud was circulated prior to the cement job, which is far short of the usual 1.5 times the hole volume that is recommended by API........This also saved 12 hours of time.
4. BP has been criticized for running production casing instead of a liner. The liner would have been sealed inside the next higher liner which would have given an additional seal to prevent migration of formation fluids. ...............
5. There was testimony that BP only used 6 centralizers instead of the recommended 21 on the production casing. ......Centralizers keep the casing in the middle of the hole to improve the cement bond."

The writer of the article, however, thinks the "key cause of the blowout is simple human error on the part of the BP head drilling engineer, who did not notice that the well was kicking. The well was likely kicking all afternoon and evening, and no one noticed until gas was coming out of the riser. It is inexcusable to allow this to go unnoticed for such a long time."

(Continuation of article referenced in previous post.)