Helium One Global (AIM: HE1), the primary helium explorer in Tanzania, is pleased to announce that the Company has successfully completed wireline logging and downhole sampling at the Tai-3 well.
· Downhole fluid samples successfully recovered from reservoir intervals in the Upper and Lower Karoo Group confirm the presence of helium
· Complete wireline logs and initial petrophysical analyses demonstrate good quality reservoir sands in the Upper and Lower Karoo Group, interbedded with well developed shale prone seals; data recovered demonstrates a stratigraphic section, previously undrilled in the Rukwa Rift Basin
· Onsite pressure-volume-temperature analysis of downhole fluid samples have yielded helium concentrations up to 8,320 parts per million (“ppm”) helium, which measure significantly above normal background levels of approximately 5ppm
· No Basement downhole samples were obtained as the wireline tools could not be run past 1,430m measured depth (“MD”) due to washouts and ledges
· Tai-3 well has now been suspended for future operations that will involve drilling deeper into the Basement target, where an increase in helium shows were encountered whilst drilling
· Information and data obtained from the Tai-3 well results have provided a much greater understanding of the active working helium system in the region and a new well location on the Itumbula prospect has been identified as a result of these findings
· On completion of rigging down at Tai-3, the Company’s drilling rig will be moved to the new Itumbula location where the iron rough neck and hydraulics will be repaired
· Upon completion of the repair and maintenance work, the Company plans to continue the drilling campaign
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 from 2-20m 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.
Lorna Blaisse, Chief Executive Officer, commented:
“These results are very encouraging indeed and we are delighted to have completed the Tai-3 well safely and to have been able to acquire a full set of wireline logs and downhole samples. This is an excellent result for the Company and a huge testament to the team’s performance, especially given the challenges we have faced along the way.
Whilst disappointing that we were unable to run the wireline tools further into the Basement target at this time, given the increased helium shows we saw at this depth, we are confident that by casing the well and suspending Tai-3, we will be able to return at a later date and target the fractured Basement helium play which we believe to have significant potential.
We have continued to demonstrate that there is an established working helium system in the Rukwa Basin and the Tai-3 well has given us a fundamental set of geological learnings, which we now intend to apply to the Itumbula prospect.
Once Tai-3 has been rigged down we will move the rig to Itumbula where our primary focus will be on repairing the Predator 220 rig and, armed with valuable information and data gained from Tai 3, moving onto our second well of this drilling campaign on Itumbula.”
If anyone reads this article found it useful, helpful? Then please subscribe www.share-talk.com or follow SHARE TALK on our Twitter page for future updates.
Terms of Website Use
All information is provided on an as-is basis. Where we allow Bloggers to publish articles on our platform please note these are not our opinions or views and we have no affiliation with the companies mentioned