‘The devil is in the details’ – petroleum geologist says of CGX’s Guyana discovery

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Editor-in-Chief at GEO ExPro, Henk Kombrink, questioned why companies would announce a discovery when the actual proof is not there, following a March 18 release from Vancouver-based explorer MCF Energy that announced a “significant gas discovery” at its Welchau-1 well in Austria. 

He pointed out in a March post that, though it sounds exciting, MCF said, “A suite of wireline logging tools, along with an MDT formation test tool, will be deployed for downhole pressure measurement, inflow testing, and formation fluid sampling in the targeted zones.”

On this basis, the petroleum geologist said it may have been too early to call that a discovery. He said there are many wells where shows were reported that never made it into a commercial development. 

Kombrink brought up drilling results from CGX and Frontera in Guyana, noting that the duo had to explain to investors last year that the announcement of a significant hydrocarbon-bearing Santonian sandstone interval did not equal a similarly thick pay zone. 

“The devil is in the detail, details that can be measured through a proper wireline and pressure testing campaign,” Kombrink stated.

CGX and Frontera experienced a marked downturn in their stock values after they detailed the results of their exploration in Guyana at the Wei-1 well in the Corentyne Block, in a November 19, 2023 press release, and accompanying conference. The joint press release indicated a discovery of 40 feet of net pay at the Wei-1 well’s Santonian interval. They had announced a discovery of 210 feet of hydrocarbon-bearing sands in the Santonian in June.

Aside from the Guyana case, Kombrink pointed out the example of well 30/7-7 in the Norwegian North Sea, for which, the report was of major gas shows in the Jurassic. He said a subsequent DST failed to get gas to surface because of the formation being tight. 

Kombrink said it can probably be stated that it is quite rare to drill a well into a sedimentary basin without any signs of hydrocarbons. 

Back to Austria, he said the Welchau well, drilled by both MCF and Australia-based ADX, targeted the Steinalm reservoir. 

Plagued by challenges, CGX promises first oil offshore Guyana by 2030 | OilNOW

“It is a fractured Triassic limestone that already proved to contain hydrocarbons in a well drilled nearby (Molln-01) in 1989. The press release also emphasized that above the reservoir, a 380 m sealing unit was found, belonging to the Lunz Formation. The presence of a strong gasoline odor released from the core is also being described in support of the potential of this ‘discovery’.”

Calling this circumstantial evidence, Kombrink said the presence of a sealing unit is not a guarantee that a closure exists. “… and with this well being located onshore in a tectonically complex area, who says that there are no leaks?” he said. 

Kombrink said it is only after completing a log run, that a well can be properly classified as a success or a dry hole. 

MCF’s subsequent releases have not indicated a quantity of net pay at the Welchau-1 well. In an April 2 release, MCF said a program of extensive analysis was underway.

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