The Rubiales heavy oil field, located in the Llanos basin in eastern Colombia, is reportedly the single largest producing oil field in the country, with over 165 Mbbl/d average total gross field production last year.

Pacific Rubiales operates the field and holds an approximate 41.8% gross working interest, while the remaining working interest is held by Ecopetrol, the national oil company of Colombia.

Pacific Rubiales chief executive Ronald Pantin said receiving the water injection licence will allow the firm to increase total oil production in the giant Rubiales field to a target level of 190 Mbbl/d by the end of 2012, up from 172 Mbbl/d during the first half of this year.

"We have pre-built the necessary water injection facilities and have oil behind pipe, which will allow us to increase oil production relatively quickly," Pantin added.

The company is also expecting to obtain commerciality approval for the development of the Quifa North oil field from its partner Ecopetrol, and the environmental exploration license from the ANLA.