The owner of the rig that exploded in the Gulf of Mexico last year largely blames oil giant BP for the disaster in an internal investigation report...that goes a long way in bolstering the Swiss firm's arguments in responding to pending lawsuits and expected government fines. The Transocean report said the April 20, 2010, Deepwater Horizon explosion and resulting oil spill was sparked by a succession of well design, construction, and temporary abandonment decisions that compromised the integrity of the well and compounded the risk of its failure. Transocean said many of the decisions were made by well owner BP in the two weeks before the incident...BP's own internal report on the disaster blamed a cascade of failures by multiple companies for the disaster. Government investigations also have spread around the blame.