Everett had the contract with Statoil. Bristow had 2 contracts with Everett, 1 for personnel, the other for aircraft. Everett provided one of the fines helicopter hangars in Africa and its own private passenger terminal.
What makes you think Everett made life difficult for Bristow? The Bristow contract was with Everett, not Statoil, so naturally they had oversight. The year after Statoil pulled out of Tanzania, the former Bristow director for Africa joined Everett as COO.