This follows the withdrawal of the US operator and another minor US participant from the oil and gas project, co-venturer Adelaide Energy said this morning.

As a result, Adelaide Energy says it has increased its working interest in 12,000 acres of the project area from 15% to 25%, and in 13,000 acres from 10.5% to 17.5%.

The first well in the project, West Florence-1, was placed on production in October and is currently producing 5-10 barrels of oil per day from the Codell Formation.

As well as looking at how to increase this output, the operator is also looking to advance the project with the drilling of a further well to evaluate the Pierre Shale Formation.

This fractured shale historically produced about 15 million barrels up to the 1940s from the adjacent Florence oil field.

Additionally the JV plans to shoot a 3D seismic survey in the West Florence acreage to advance development of the project.

The West Florence project is located in the Florence sub-basin of the Denver Basin, about 160km south of Denver.

Potential petroleum resources for the West Florence play is estimated to be up to 15 million barrels of oil if present and within three targets in the Pierre, Niobrara and Codell formations.