b'Seismic window Seismic windowMichael Micenko Associate Editor for Petroleum mick@freogeos.com.auSeismic reflection and hard rocksI recently caught up with an old mate in Brisbane and he suggested I write an article on HiSeis\x08 Whats that? I asked\x08 AFigure 1:P impedance vs Poissons ratio cross plot showing separation of various minerals (modified from company using seismic in the search forHeureux et al, 2005).minerals\x08 Theres some people in Perth doing it he replied\x08 a lack of prominent marker horizons, aand tools such as VSPs and tomography scattered signal and low signal to noiseto produce high quality images of the I havent been following theratio in an often complex geologicalsubsurface\x08 The detail at depths up to developments in hard rock explorationsetting\x08 2 km cannot be provided by any other lately so I set about doing some research\x08method\x08 They have worked hard to My previous experience was in 1979A Canadian group (https://csegrecorder\x08 optimise the entire workflow from survey when Reg Nelson, who was then at thecom/articles/view/3d-seismic- design, acquisition, processing and SA Mines Department, recorded someexploration-for-mineral-deposits-in- interpretation and developed unique experimental lines - over Olympic Damhardrock-environments ) has foundtools\x08I think\x08 The data could be described asthat massive sulphides have an poor, and I never saw a reflection onAmplitude Variation withangle OffsetThere are some well respected names the paper sections\x08 But that was then,(AVO) response similar to hydrocarbonbehind this push into hard rock seismic, and seismic imaging has progressedsands, so they have found bright spotwith several projects conducted by significantly in the last 40 years\x08 Usingtechnology to be useful\x08 Its not thatCurtin University until the technology reflection seismology to delineatesimple though, and like oil and gaswas spun off as HiSeis in 2009 under the ore bodies and help plan mine sites issands, the velocity and density within aguidance of Anton Kepic and Milovan now routine for some companies, andsulphide deposit varies with mineralogyUrosevic\x08they have been achieving results that(Figure 1)\x08 For instance, pyrite and were previously not possible\x08 But it hasfelsic minerals increase velocity asI am no longer a sceptic and my next step not been a universal embrace of thedensity increases but chalcopyrite,is to actually see what the seismic looks technology, and others are still strugglingsphalerite and pyrrhotite decrease inlike and how it has helped my hard rock to come to terms with the concept\x08 Butvelocity as density increases\x08 Figure 1cousins\x08for those who tried, seismic has been anshows the impedance and Poissons effective, reliable and efficient methodratio of several minerals, with a clear and can provide 3D coverage of anseparation between pyrite and otherReferenceore body whereas drilling is slow andminerals\x08 But most of the minerals have expensive and only provides informationa similar P impedance and PoissonsE\x08L\x08 Heureux, B\x08 Milkereit and E, Adam, at the well locations\x08 ratio can be used to separate the various2005\x08 Seismic exploration for mineral mineralogies\x08 Poissons ratio utilisesdeposits in hardrock environments, Using seismic reflection to image hardshear wave information which is oftenCSEG Recorder, 30 (91)\x08rocks is not simply a matter of replicatingazimuth dependent, so surveys need to processing procedures in the oil & gasbe designed to sample all azimuths\x08industry\x08 Hard rock exploration has itsEditors note: HiSeis is an ASEG own set of problems, with the older rocksHiSeis, the company, is based in Subiaco,Corporate Plus Sponsorbeing inherently homogenous causingPerth, and utilises modern equipment 29 PREVIEW FEBRUARY 2021'