Documents discussed during congressional hearings June 17, 2010, suggested that a battery in the device's control pod was flat and that the rig's owner, Transocean, may have "modified" Cameron's equipment for the Macondo site (including incorrectly routing hydraulic pressure to a stack test valve instead of a pipe ram BOP) which increased the risk of BOP failure, in spite of warnings from their contractor to that effect.
Transocean, Pride International, Seadrill, Noble Corporation and Atwood Oceanics are a few of the companies that own and operate drillships globally.
GlobalSantaFe Corporation, an offshore oil and gas drilling contractor that merged with Transocean in 2007