Helium One Global announced that the Company has successfully completed wireline logging and downhole sampling at the Tai-3 well. The Company has now successfully completed drilling and wireline operations at the Tai-3 well, despite a number of unexpected operating challenges,. These wireline operations have included logging, and downhole pressure tests and sampling.
The Company was able to successfully run logging tools down to 1,430m MD (compared to the current TD of 1,448m MD) and acquired downhole fluid samples from four different zones in the Lower and Upper Karoo Group. Petrophysical analysis of the downhole logs demonstrated little to no zones of interest for sampling in the Lake Beds or Nsungwe Formation. The wireline logs have demonstrated a series of good quality, stacked reservoir intervals in both the Upper and Lower Karoo Group sections.
In particular, the deeper Lower Karoo Group section which had not previously been drilled in the Rukwa Rift Basin and initial petrophysical analysis has demonstrated a series of well-developed good quality reservoir sands. These sands range from2-20m thick, an average 17% porosity and 0.44 net to gross, interbedded with shale prone seals. These reservoir-seal pairs, combined with their proximity to the Basement helium source, makes this interval a very interesting primary zone.
The Upper Karoo Group section demonstrates an increased shale content, and more thinly bedded reservoir intervals. The Lake Bed Formation is dominated by sandstones and shales, with minor amounts of limestone. Initial petrophysical analysis of wireline logs over the Lake Bed Formation demonstrates good to excellent quality reservoir sands (average 24% porosity and 0.61 net to gross) interbedded with thin claystones and limestones.
The downhole sampling programme, using a Baker Hughes Reservoir Characterisation Instrument, successfully recovered samples from four different intervals in the Lower and Upper Karoo Group. Although, no free gas samples were obtained, there was evidence of helium gas in solution when the samples were transferred at surface, and pressure-volume-temperature analyses were performed. These samples yielded helium up to 8,320ppm helium, with the highest values encountered close to a small, faulted zone in the Lower Karoo Group.
It is noted that helium shows increased whilst drilling into the Basement fracture zone until losses were encountered and drilling operations were halted The presence of these helium-enriched fluids migrating through the basin along fractures and fault zones that is likely to allow the helium to migrate from the deeper Basement source rock. As a result of this increased understanding of the regional characteristic, the Company plans to drill deeper into the Basement with a view that this trend continues, and helium concentrations continue to increase at greater depths. On this basis, the decision has been made to run 7" casing and suspend the Tai-3 well, so Helium One can return at a later date and deepen the well.
The Company is also in the process of reviewing the geology of the Itumbula prospect, in light of information gleaned from Tai-3. The Itumbula prospect is bound by one of the largest faults in the basin, and this is associated with a prolific surface helium seep which has measured up to 10.4% helium. The results from the Tai-1 and Tai-3 wells seem to indicate that it is the faults and Basement fractures that are releasing the highest concentrations of helium and, therefore, the Company now intends to target the western bounding fault of the Itumbula prospect during the second phase of this drilling campaign The Company is still finalising the details of the repair work that is required for the rig and will provide updates as soon as that information is available; as well as plans for the revised well location once concluded.