Alba Mineral Resources (LON:ALBA) told investors via UK Oil & Gas Plc (LON:UKOG), which owns operator Horse Hill Developments, that the flow testing operations in the Kimmeridge Limestone 4 (KL4) zone have now begun.
The company also revealed that a new report, by consultant Xodus, has determined that the single HH-1 well "sees" between 7mln and 11mln barrels of connected oil in place in the conventional Portland reservoir.
Meanwhile, a long-term production scoping report has been submitted to Surrey County Council.
It will include a total of six production wells, with up to 3 production wells and a reservoir pressure support well in the Portland oil pool.
A planning application for the production operation is due to be submitted to the council before the completion of the extended well test programme.
"The Portland continues to out-perform our initial expectations and looks set to provide the production and cash flow base that can underpin UKOG's future growth,” said Stephen Sanderson, UKOG chief executive.
“Our immediate operational focus now switches to the Kimmeridge EWT, which, if successful, has the potential to make Horse Hill one of the UK's leading onshore producing oil fields and to help unlock the value within our extensive Kimmeridge asset portfolio in the Weald."
George Frangeskides, chairman of fellow Horse Hill stakeholder Alba Minerals, said: "These ambitious plans revealed by the operator to drill up to a further four wells at the Horse Hill site, on top of the already planned HH-1z side-track well and HH-2 new well, supports our belief in the potential for Horse Hill to provide material production and cash flow returns to Alba in the medium to long-term.
“In the short-term, meanwhile, we await the results of the current Kimmeridge EWT, which we hope will further underpin the plans to submit a planning application for the commencement of full-scale production."