REWARD MINERALS LTD Reward Minerals Ltd. provided the following update on its 2021 drilling campaign in the Officer Basin in Western Australia. Five drill holes were completed between August and December 2021. Two of these were drilled as part of the 2020 Phase 1 program, including a re-drill of OB004 (OB004B) and OB005, which also required a re-drill (OB005B) due to technical issues encountered during drilling.
OB006 - OB008 were subsequently drilled between November and December 2021 as part of the Phase 2 drill program, following receipt of Heritage Clearance in October 2021. All holes were executed using mud rotary drilling techniques for a total of 1,147 metres. The purpose of the drilling was to follow up on significant, Potash-rich brine flows encountered previously in holes OB001 - OB004 drilled during 2020.
The 2021 drilling at Officer Basin confirms the presence of substantial groundwater occurrence in the area/s drilled. However, generally the tenor of dissolved salts in the groundwater recovered from the drill holes was disappointing, particularly in view of the much higher Total Dissolved Ion (TDI) content of brines encountered in holes OB001 - OB004 during 2020. While it appears that near-surface groundwater is relatively fresh and that TDI generally increases with depth, the drilling crew experienced great difficulty in isolating the upper, freshwater aquifers from deeper, brine-containing aquifers (of significantly higher salinity).
Thus, it is difficult to quantify the dilution effect on deeper groundwater by shallower inflow during the process of pumping and subsequent airlift recovery. Ground conditions including running sands underlain by dense clay formations made drilling difficult with frequent loss of mud circulation, and drilling equipment getting stuck or lost downhole on a regular basis. Results of the Officer Basin drilling to-date provide the following indications: Drilling of the deeper holes OB001 and OB002 (cored to 419.45m and 705.6m respectively) failed to return solid evaporites containing water-soluble potash salts.
Core analysis of OB002 to include formation dating to confirm whether the targeted rock sequences were in fact reached, has yet to be finalised. These dating results may provide a guide as to whether deeper drilling to penetrate the Browne Formations sediments is warranted. The shallower drilling executed in 2021 in holes OB005 - OB008 and limited groundwater recovery trials support Reward's view that a large palaeovalley system runs from (at least) OB001/OB002 in the east across the Warnturr and Timpirr Lakes corridor to the west, a distance of >40km.
The low-density tenor of groundwater in recent holes OB005, OB006 and OB007 suggests that these holes are located on the margins of the postulated palaeovalley aquifer. OB008 demonstrated a significant Potash content in groundwater drawn from the bottom of hole at 202 metres. Potassium analysis of 1.49kg/m3 and sulphate of 13.9kg/m3 are regarded as encouraging (SOP equivalent of 3.3kg/m3 of brine).
Based on that assumption, Reward proposes to conduct a geophysical survey involving Passive Seismic Surveying, both across and perpendicular to the postulated flow direction of the palaeovalley. Survey lines will effectively run parallel to Seismic Line N83-1. Passive seismic is a relatively low-cost, non-ground disturbing technique used extensively in Western Australia to define depth of cover, shallow stratigraphy and direction and depth of palaeovalley water and brine resources for mining and other (Potash) operations. Follow-up drilling has confirmed the effectiveness of the method in other regions.
The implementation of the Passive Seismic Survey will require approval from WDLAC and the Martu Traditional Owners in order to gain access to the Warnturr and Timpirr Lake areas which are of Cultural Significance to the Martu and are Registered Sites under the Aboriginal Heritage Act 1972. Reward will seek to discuss access considerations prior to any further planning of geophysical survey activities.
