Partners in the Corentyne block – Canada’s CGX Energy and Frontera Energy – have revised the total cost estimate for an exploration well, which recently found oil-bearing intervals, and its drilling programmed offshore Guyana, which is being carried out by a Noble-owned rig.

Back in February 2022, Frontera and CGX disclosed a plan to spend up to $130 million on their second exploration well on the Corentyne block, called Wei-1 with the spudding of the well originally slated for October 2022, using the Maersk Discoverer (now called Noble Discoverer) semi-submersible rig.

However, once November 2022 rolled in, the two players revised the spud window for the Wei-1 well after the Noble Discoverer rig run into delays on its assignment with Shell in Trinidad and Tobago. As a result, the start of drilling operations in Guyana was anticipated between December 2022 and late January 2023.

The Wei-1 well was spudded in January 2023. This well is located on the Corentyne block, approximately 200 kilometres offshore from Georgetown, Guyana. It is planned to be drilled to a total depth of 20,500 feet and to date has been drilled to a depth of 19,142 feet (5,834 metres). This well is situated approximately 14 kilometres northwest of the Joint Venture’s previous Kawa-1 light oil and condensate discovery.

According to Frontera Energy, the Wei-1 well has encountered oil-bearing intervals in the western channel fan complex of the northern portion of the Corentyne block in formations of Maastrichtian and Campanian ages, as a comprehensive logging campaign in these intervals indicated the presence of oil, confirmed by downhole analysis.

Furthermore, the company highlights that logging while drilling (LWD) and cuttings indicate the presence of hydrocarbons in the upper portion of the Santonian. As fluid samples have not yet been fully obtained, side-wall core samples will be attempted in the Santonian interval when drilling resumes.

While preliminary indications from the secondary targets in the Maastrichtian and Campanian are positive, Frontera underlines no assurance can be given that these activities will ultimately produce hydrocarbons in commercial quantities. Moreover, a wireline fluid sampling tool became stuck in the well while performing additional well logging and data acquisition operations, which was not recovered.

Frontera points out that an open hole sidetrack will begin shortly from below the last casing point and will progress to the planned total depth. The Guyana partners expect to complete Wei-1 operations within the original 4-5 month timeframe, as announced on 23 January 2023.

On the other hand, the Joint Venture has updated its Wei-1 well total cost estimates to $175-$190 million to reach the target total depth and complete its drilling programme. Frontera outlines that this increase in cost entails the delays associated with the late arrival of the rig, costs associated with fishing and sidetrack operations and post-well evaluations.

The 2009-built Noble Discoverer, which was hired for this assignment, is a DSS-21 column-stabilized dynamically positioned, sixth-generation semi-submersible drilling rig, capable of operating in water depths of up to 10,000 ft.