A helium gas show was discovered during the Helium One drilling operation, the Rukwa Project, in Tanzania.
A gas show is when, during operations, there is a recorded increase in gases above a baseline amount, indicative of the potential of the formation under investigation.
Elevated helium levels were encountered as connection gas as Helium One continued exploration drilling at Tai-1 well. The gas shows were identified at primary targets from 552 metres to 561 metres as measured by the on-line gas chromatograph.
The transient peaks suggested that helium saturated brine was present through the system, with potential for free gas to form beneath sealing units.
Drilling was halted afterwards due to parting of the drill-pipe. Parting on a fatigued joint, 12 stands and drill bit are currently sitting on well bottom.
Above the primary targets sits the Red Sandstone Group, previously considered to be of low prospectivity due to a lack of effective sealing units. Occurring beneath a thin clayston unit, the gas show demonstrated a working helium system, whereby gas shows may also be identified beneath even marginal sealing units.
Commenting on the gas show, David Minchin, Chief Executive Officer, Helium One, said, “The identification of helium gas shows in the Red Sandstone Group between 552 and 561 metres is another unexpected, but positive result as this zone was previously considered to be of low prospectivity.”
“This gas show, along with our earlier reported gas show announced on 22nd June, demonstrates a working helium system and supports helium prospectivity for additional gas shows throughout the stratigraphy.”
Indications of increase levels of gas bubbles in return mud at the surface provide visual evidence of a potential gas show, but, in lieu of direct evidence, the bubbles may have entered the return drilling mud from other sources.
Other more direct methods such as wireline logging and testing will have to be conducted before a formal discovery can be confirmed.
Speaking about the loss of drill string, Minchin said, “The delay caused by the loss of drill string in the midst of the drilling is unfortunate, however contingency plans have been implemented to sidetrack from above the lost pipe and continue drilling to test both the Red Sandstone gas show and priority target horizons beneath.”
“This option allows us to utilise the existing 483 metres of already completed drilling rather than relocating to a new location.”
With the more direct indicators already identified, Helium One look forward to a successful completion of drilling on this target location.