Trinity Exploration & Production PLC (AIM:TRIN) shares jumped 19% higher in early trade following the confirmation of the Jacobin-1 oil discovery, onshore Trinidad.
CEO Jeremy Bridglalsingh hailed this as a "very significant achievement".
The discovery of "virgin oil" in a super-mature basin represented a "step change" in the company's understanding of the oil and gas system, he added.
The well, located in the prolific Palo Seco area, was drilled to a depth of 10,021 feet, making it one of the deepest in the area in recent times.
It encountered over 290 feet of net oil pay, including 63 feet in the deeper exploration targets. The results are within the expected range for a commercial discovery, and flow testing is planned to commence in September.
Oil is expected to be sold immediately post-drilling completion, demonstrating the speed at which it can generate revenue.
The results also validate the geological model, indicating the existence of a deeper play across Trinity's entire Palo Seco area and the recently awarded Buenos Ayres block, investors were told.
At 8.30 am, the shares were changing hands for 88p, up 13.8p.