Replacing and reporting to Mr Albrecht, as Oxy Oil and Gas’s vice president for California operations, is Todd Stevens.

Mr Stevens has been instrumental in leading Occidental’s mergers and acquisitions team and will continue as Occidental Petroleum’s (Oxy) vice president for acquisitions and corporate finance, until a replacement has been named.

Prior to his current assignment, Mr Stevens held a series of progressively significant finance roles during his 13-year career with Oxy.

Dr Irani said: Bill’s primary focus will be to optimize the operational effectiveness and business returns of our significant US holdings and assets. This assignment will take advantage of Bill’s extensive oil industry experience.