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We are pleased to advise the fifth instalment of our quarterly MinEx CRC vNews is now available.
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MinEx CRC researchers have identified centrifuge operating parameters (most importantly bowl rotation speeds) required to optimise separation of solids and drilling fluids at flow rates and fluid viscosities typical of coiled tubing (CT) drilling.
Centrifuges, for the separation of solid phases from drilling fluids, are critical components of the Hydraulic Processing System (HPS) which delivers clean drilling fluid vital for CT drilling. To date, the centrifuges used for solid separation in the drilling industry have been optimised for fluid parameters typical of diamond drilling. There has been little understanding of centrifuge performance over the range of fluid parameters encountered during CT drilling, including higher fluid viscosity, higher flow rates and coarser solid load than diamond drilling.
MinEx CRC established a stand-alone project to address the issue of centrifuge performance in the context of CT drilling. The project relies on extensive experimental study, characterising the performance of centrifuge decanter under different CT drilling conditions. We have set up a field-scale centrifuge decanter in our dynamic loop experimental facility at Curtin University. Our first experiments have shown a sensitive relationship between centrifuge performance and bowl rotation speed – which in some circumstances requires adjustment of the centrifuge outside the typical operating range. Preliminary findings suggest that the optimised operating parameters are achievable (and safe!) and can be accommodated in the HPS design.
Our findings pave the way for an efficient CT drilling platform and will be used to tune and optimise the control system of the centrifuge component of the HPS – to match and constantly adjust to fluid characteristics and drilling conditions. We look forward to deploying a prototype version of the optimised centrifuge and control system in CT drilling operations during 2021.
MinEx CRC researchers have built the first prototype of a downhole chemical analysis tool based on laser-induced breakdown spectroscopy. This prototype will allow almost real-time in situ collection of geochemical data and will be tested under simulated and real downhole conditions.
MinEx CRC aims to deliver a tool capable of being lowered into a small-diameter drillhole with the ability of providing real-time elemental analysis of the exposed drillhole surface. Based on the laser-induced breakdown spectroscopy (or LIBS) technique, the tool has the unique ability of being sensitive to almost every element of the periodic table – especially the light elements Lithium, Sodium, Carbon and Boron…even right down to Hydrogen!
Initially, the team built and tested a proof-of-concept benchtop prototype and tested its performance for analysis of a moving multi-mineral surface. The successful results of this work led directly to the design of an ultra-compact and powerful pulsed laser, combined with some very clever re-engineering of existing high-resolution ultra-compact spectrometers, which formed the basis of the downhole LIBS prototype. Close working relationships between the overseas laser and spectrometer manufacturers, and CSIRO colleagues expert in optics, electronics and mechanical engineering, has resulted in a world-first ultra-compact downhole elemental analyser that contains both the laser and the spectrometers.
We will continue to test and further develop the downhole assay tool prototype and its performance under the most challenging downhole conditions so that future company drilling programs, as well as the National Drilling Initiative, are able to benefit from obtaining rapid geochemistry data in in ultra-short turnaround times alongside the drilling program. This revolutionary capability promises to deliver almost real-time decision making out in the field.
MinEx CRC has completed two drilling campaigns in the Barkly region of the Northern Territory. We drilled a single 1750 m hole deep hole in the South Nicholson basin, close to the Queensland/NT boarder, and ten holes totalling 4000 m in the East Tennant area, between Tennant Creek and the Barkly homestead.
There have been very few samples of the deeply buried basement rocks in the Barkly region, which lies between the highly mineralised Mt Isa and Tennant Creek mineral provinces. This lack of samples has severely limited our understanding of the geology and mineral prospectivity of the area and has discouraged exploration. The NDI drilling provides some of the first samples ever so that we can start to understand the basic stratigraphy, lithology, structure, alteration and also data on groundwater.
The drilling was preceded by an extensive precompetitive geoscience data acquisition program called ‘Exploring for the Future’ that was delivered by Geoscience Australia and supported by the Northern Territory Geological Survey. This work suggested a couple of areas of great interest for further investigation by drilling.
The drilling was conducted by DDH1, and managed in the field by OmniGeoX. It was delivered on time, within budget, with no lost time incidents, and it’s fair to say that the program more than achieved the science objectives. High praise needs to go to Geoscience Australia for the years of geoscientific work that has gone into the area selection and drill targeting; to OmniGeoX for managing the field activities including data acquisition, DDH1 for conducting the drilling, and to the Northern Territory Geological Survey for various areas of support.
All of the data acquired during drilling and wireline logging, together with Hylogger and Minalyse scanning, will be made publicly available shortly via the MinEx CRC Portal, and over the next year or so more specialised analytical work will be conducted and released by the MinEx CRC research consortium.
This precompetitive drilling campaign provides some of the first data in what looks like promising areas for use by both explorers and policy makers. Minerals and energy industries have already shown strong interest in the areas ahead of drilling, but this geoscience data will also be of use to other users, and will make a contribution to the long term development of the Barkly Region.