ABSTRACT
In recent years, however, a number of proposals have been made for using microorganisms actually to improve the efficiency of oil production from the reservoir; collectively they have often been called microbial enhanced oil recovery. Their attractiveness lies in the promise of low cost and simplicity of operation but all are in the development stage and few have been extensively tested in the field. Although not without its difficulties, the industry has been hugely successful in prospecting for and producing oil. In spite of its vast experience, the amount of oil economically producible on a worldwide basis from a typical reservoir by current technology nevertheless falls far short of complete recovery. Crude oil is an extremely complex and variable mixture of compounds; some samples are said to contain thousands or tens of thousands of different chemical species.
