Eco Atlantic Oil & Gas Ltd has announced a major new oil discovery in the Orinduik block offshore Guyana.

The explorer this morning told investors that the Jethro-1 well has encountered a high-quality oil-bearing sandstone reservoir with 55 metres (180.5 feet) of net pay.

It is a significant and transformational discovery for Eco not least because it proves that the very large and prolific oil system present in Exxon’s next-door discoveries continue into the Orinduik area.

Eco shares rocketed more than 100% higher in Monday's early deals, rising 74p per share to trade at 139p.

Jethro-1 will now await further evaluation, to determine the next steps for appraisal, and, the Stena Forth drillship will be deployed immediately to its next target, Joe-1.

Eco owns a 15% in the project and via farm-out deals its share of exploration costs are covered by partners.

Orinduik is also 60% owned by Tullow Oil and 25% owned by Total.

Exxon has made thirteen consecutive discoveries in the adjacent Stabroek block, together comprising a multi-billion barrel project. The most advanced discovery is Liza which is due to start producing for Exxon in 2020.

“Jethro is a fantastic find for us,” said Colin Kinley, Eco co-founder and chief operating officer.

“The Jethro-1 well confirms the continuance of the petroleum system onto the Orinduik Block, up-dip from the prolific discoveries on the Exxon operated Stabroek Block.”

“We have multiple drilling targets on the block with similar geophysical characteristics and we are moving the Stena Forth drillship immediately to its next target, Joe-1.”

Gil Holman, Eco chief executive, added: "We are thrilled to report this exceptionally exciting discovery.

“This is a revolutionary moment for Eco.

“It has been a long path of hard work for our team, and with today's announcement we feel our first rewards have justified our journey.”

He highlighted: “This is a transformational event for the company, and we now need to strategically plan for an even brighter future.  

“With multiple targets to consider, and Joe as the next prospect to be drilled, we will now pursue our evaluation of the timing for wells to develop the Jethro field and to expediently bring it on production. We are funded for at least six additional wells.”