Bacteria to help retrieve oil out of India’s sick wells

A brown-coloured cocktail of bacteria might soon help squeeze crude oil out of India's sick oil wells and boost production. Indian scientists have developed a mixture of three bacteria that help extract oil from onshore oil wells that do not yield oil any more by conventional methods.
The bacterial cocktail can enhance oil production from a depleted oil well by up to three times, said researchers at the Tata Energy and Resources Institute (TERI) and the Oil and Natural Gas Commission (ONGC) who discovered the bacteria.

Thousands of oil wells retain up to 60 % of their crude oil even after they are declared "sick" because conventional methods fail to pump it out. The bacteria are injected deep into the wells where they produce biochemicals and gases that build pressure inside and "force" the residual oil out, said Dr Banwari Lal, a microbiologist and fellow at TERI.
The technology has been successfully field-tested by ONGC in at least 12 wells in Gujarat and will be deployed on a trial basis in another 20 wells next year, said Lal. A single injection of the bacterial cocktail into the used-up oil well can enhance oil production for up to three months. TERI and ONGC plan to file for an international patent on this technology.

A single bacterial injection costs about Rs 2 lakh, but through the enhanced oil production, the cost can be recovered within a month and profit comes within two months, said researchers. Conventional methods of oil extraction can recover only about 40 % of crude oil in a well.
Scientists elsewhere have long pursued bacteria-aided oil extraction, but the discovery of special bacteria may help India apply indigenous technology in its own wells.

The three bacteria were discovered in oil wells. They belong to a class of organisms called "extremophiles" that can survive in high temperatures.

"Our bacterial consortium works most efficiently at temperatures of around 90 degrees centigrade, which is the kind of heat you find in deep oil wells," said Lal. In one field trial in an oil well at Kosamba in Gujarat, ONGC managed to extract 1,138 cm of oil from a sick well, generating revenue of $ 100,000, a report from TERI said.