Helium One plc (LON:HE1), currently drilling at its 100% owned Rukwa Project In Tanzania, has announced a further helium gas show in drilling mud in the Red Sandstone Group and sidetrack from Tai-1 well following loss of the drill string at 561 meters.
· Helium gas shows identified in stratigraphy above our primary targets from 552 metres to 561 metres as measured by the on-line gas chromatograph
· Gas show supported by indications of gas visually identified as bubbles in drilling mud returns at surface
· Helium shows continued to 561 metres, at which point drilling operations were suspended due to parting of drill pipe in the midst of drilling the gas show
· Mitchell Drilling has been unable to recover the lost drill pipe from the hole to date with subsequent delay to drilling operation resulting in the management decision to sidetrack drilling from above the lost pipe at 483 meters
David Minchin, Chief Executive Officer, commented:
“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.
“Visual identification of bubbles in mud returns also offers circumstantial evidence of free helium gas in the sub-surface. However, it is important to note that this interval needs to be logged with wireline before a pay zone can be determined.
“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 meters of already completed drilling rather relocating to a new location.
“With the above indicators already identified we look forward to a successful completion of drilling on this target location.”
Helium One has continued exploration drilling at Tai-1 well, with elevated helium levels encountered as connection gas. These transient peaks suggest the presence of helium saturated brine throughout the system with potential for free gas to form beneath sealing units. Drilling rates have been moderated to ensure consistency of mud composition in variable stratigraphy.
At a depth of 552 metres, the Helium One mudlogging crew detected elevated helium in mud that constitutes a gas show. The gas show continued to increase over a thickness of 9 meters, at which point drilling was halted due to parted drill-pipe. The drill-pipe parted above a fatigued joint, with 12 stands and drill bit currently sitting on well bottom.
The Red Sandstone Group sits above our primary targets and was previously considered to be of low prospectivity due to a lack of effective sealing units. The gas show occurred beneath a thin claystone unit and demonstrates a working helium system, whereby gas shows may also be identified beneath even marginal sealing units.
The gas show is supported visually by indications of increased levels of gas entrained as bubbles in return mud at surface. This offers circumstantial evidence of free gas in the subsurface, however we have no direct evidence and the bubbles may have entered the return drilling mud from other sources. Free gas containing helium will need to be confirmed by direct measurement via wireline logging and testing before a discovery can be confirmed.
With Mitchell Drilling unable to recover lost pipe down hole to date, Helium One has made the decision to sidetrack from above the lost pipe at 483 metres. Time spent in attempting to recover lost pipe, sidetracking operations and re-drilling from 483 meters will delay the completion of drilling at the Tai-1 well.