According to a Wall Street Journal analysis of federal data and a June 19 report from the publication, in recent years BP used a well design that has been called "risky" by Congressional investigators in more than one out of three of its deepwater wells in the Gulf of Mexico, significantly more often than most peers. The design, called "long string" was used on the well that exploded in the Gulf of Mexico on April 20. The only other major well design, which is more expensive, includes more safeguards against a natural-gas blowout of the kind that destroyed the Deepwater Horizon.
(Source: The Wall Street Journal)