Below the surface of lawsuits blaming oil company BP for the Deepwater Horizon rig explosion, tremors of insurance disputes begin to roll. In a pair of federal suits, insurers of rig owner Transocean resist BP’s claim that it qualifies for coverage under Transcoean policies. "The issue in the suits is the scope of BP’s additional insured status under the policies," BP lawyer Don Haycraft of New Orleans wrote to U.S. District Judge Carl Barbier on Feb. 22.