Drilling at Tai-1 defined a working helium system with the Rukwa Basin. Following the revealing of seal, reservoir, and trapping geometries, a charge mechanism in the basic away from known surface seeps was also identified.
A well-developed 130m thick sealing claystone at the top of the Karoo Formation could support the trapping of helium within the reservoir formations beneath.
Further signs of helium are apparent in the Red Sandstone Formation and in shallow traps in the Lake Bed Formation.
During the Tai-2 drilling, geophysical techniques were used to identify shallow targets, potential prospects for low-cost drilling. The well targeted continuation of a 2.2% helium show identified in a sandstone interval at 70.5m in Tai-1.
Due to current seismic data not accurately resolving trapping styles at shallow depths, Helium One is looking at alternative low-cost geophysical techniques to test over known structures in the Tai area, before applying the techniques to a wider area. Shallow traps could also allow the possibility for drilling operations to continue over the wet-season with water-rigs.
Commenting on the work conducted so far, Ian Stalker, Non-Executive Chairman, said, “Work undertaken so far in 2021 has significantly de-risked the Rukwa Basin by demonstrating a working helium system.”
“Helium One maintains 100% ownership of licenses at Rukwa covering approximately 3,500km2 in what must now be considered the world’s premier basin for helium exploration.”
Tai-1 also revealed deep targets, showing good quality sealing units above reservoirs in the Top Karoo. The unit’s continuity was mapped along the Tai prospect using infill 2D seismic data, with the prediction that thickness and quality of the sealing unit will increase towards the basin centre.
Drilling also revealed large structures identifiable using Falcon Gravity Gradiometry data, in addition to seismic data. Onshore northern extensions of the Itumbula and Tai structures, these structures have potential to show stacked targets.
Helium One is looking into mobilising infill seismic to improve resolution before the wet season. This has led to the design of a deep drilling programme to begin in 2022, set to test these identified targets.
Excited about the results of the 2021 exploration drilling campaign, David Minchin, CEO, spoke about the project, saying, “Results from Tai-1 have shown a prolific basin with helium shows identified at multiple levels from near surface to basement.”
“Tai-2 has verified the potential for development of newly identified ‘Shallow’ traps within the Lake Bed Formation, which has the capacity to open a pathway to low cost exploration and development of near surface gas deposits.”
He also spoke about the potential for ‘Deep’ traps within the Karoo Formation, saying that the Top Karoo seal is predicted to be best developed away from the basin margin.
The company plans to deploy its Phase 2 exploration activities shortly and will work to begin geophysical investigations before the start of seasonal November rains.