ISATIS - Geovariances

ISATISNEWSThe Universeof GeostatisticsGeovariances Newsletter N°15 – September 2002 – MiningThe main piece of news of this second semester 2002 I’mvery proud of, is the opening of our new Geovariancesoffice in Houston, USA.Jeffrey Yarus and Rich Chambers, both famous for theirworks in geostatistics, have been respectively named asPresident and Vice-President, while Viviana Alderete asIsatis Sales and Marketing Manager.If you live in Canada, Mexico or USA, feel free to contact them.Geovariances Americas Inc.2900 Wilcrest, Suite 370, Houston, TX 77042, USA+1 713 782 8366www.geovariances-americas.comjyarus@geovariances-americas.comrchambers@geovariances-americas.comvalderete@geovariances-americas.com… Training News …A few comments after the first course on Advanced MiningGeostatistics in Belo Horizonte (Brazil)Gemcom do Brasil in conjunction with Geovariances had the pleasure toorganize in May 2002 a five-days training titled “Advanced MiningGeostatistics” focused on Non-Linear Geostatistics .Participants from various mining companies such as AngloGold, CVRD,Docegeo, Ferteco Mineração, and Samarco Mineração, were attending thisdedicated course.“I considered the course good from the point of view of being able todemonstrate the need to use non-linear techniques for the recoverablereserves estimation, the use of ordinary kriging being not recommended inthose cases. Furthermore, it was possible to compare and analyze theresults got from different methods.Maybe the course should cover a little more the stochastic simulations.”Walmir Carvalho Pereira, Mine Planning Department Chief, SamarcoMineração S.A.“Non-linear Geostatistics was a great course and a great opportunity to bein contact with Dr. Deraisme. During this week, we increased our knowledgein geostatistics and Isatis. It was a very nice chance to discuss our practicalquestions, like variography, simulations and now non-linear techniques.”Alessandro Henrique Medeiros, Ore Resources Estimation, AngloGoldA USER’S VIEWPOINTSRK AUSTRALASIAMINING RESOURCES DIVISION:“From the basic applications to the most advanced, Isatis hasthe full suite of resources capabilities unavailable in manyother software for the mining industry. Daily SRK areutilizing the fundamental tool of testing estimation quality forchoosing appropriate block sizes and search parameters. Thisis very important to avoid estimation bias and surprisinglyfew software have this capability or have it utilized to it’s fullbenefit.Isatis software contains the ability to test the quality ofthe variogram fitting outside of the modeled“… Isatis, afull suite ofresourcescapabilities…”continuity axes directions. The process ofchecking has often resulted in modifications tothe fitted model to best fit the overall gradecontinuity rather than taking what could be ablinkered view of the model.We have found that we need the journal files system forstoring a complete audit trail and in the case of repetitiveprocessing, they also reduce the time taken. The miningindustry in Australia is heading into using more advancedmethodology and Isatis has provided the non-linear(Uniform Conditioning and MIK for example) and simulationmethodologies to cope with many different situations:investigation of mining selectivity focused on blocks smallerthan can be directly estimated without distortion of the gradetonnage,modeling multivariate interdependence (usingcorrelations between variables), removing bias in gradedistribution due to clustered drilling in low or high gradeareas without losing data, global (domain) and local (block)estimation for use at different stages of drilling programs,confidence or risk analysis using both conditional and nonconditionalsimulation for drilled and non-drilled areasrespectively, simulation for grade control optimisation atoperating mines.This wide range of methodologies are regularly practiced inIsatis by SRK and many of them, plus others, have beenimplemented in this current year”.49 bis avenue Franklin Roosevelt – BP91 – 77212 Avon Cedex, France – Phone : +33 (0) 1 60 74 90 90 – Fax : +33 (0) 1 64 22 87 28 – www.geovariances.com2900 Wilcrest, Suite 370 – Houston, TX 77042, USA – Phone : +1 713 782 8366 – Fax : +1 832 251 0586 – www.geovariances-americas.com

ISATISNEWSThe UniverseofNewsletter N°15 – MiningQUANTIFICATION OF THE RISK IN THEEVALUATION OF KIMBERLITE VOLUMES, BYJ.DERAISME, GEOVARIANCES AND D.FARROWDE BEERS CONSOLIDATED MINES LTD.An interesting application of geostatisticalsimulations has been achieved in a attempt toquantify the risk in developing deeper levels ofkimberlite mines. The objective was to optimize thesampling strategy in order to guarantee a givenconfidence in the estimate of production on aannual basis.The rock-types have a rather simple geometry andthis allowed an efficient geostatistical approach tobe carried out. This involved the simulations ofvariations in boundary positions of differentrock-types from an existing Base Case geologicalmodel, which was generated using informationobtained from production levels. The geologicalmodel is then considered as a guide and we haveto simulate fluctuations around it.After having performed several simulations, we canconsider them as possible images of the reality. Onthe figure below, the two rock-types simulated on agiven levelare paintedin color,while theestimatedoutline of thepipe isrepresentedby a blackline. Thesimplifiedshape of theestimatedoutline is tobe expected when only a limited number ofboreholes are used. By repeating the exercisewith different boreholes layouts, we cancompare the estimated volumes to the simulatedones. From several simulations, we get then adistribution of the estimation errors for each layout,hence we can perform statistics and risk analysis.The first point, that makes this study of particularinterest, is that the sampling of simulations canquantify the uncertainty in a very practical sense,i.e. number and position of future boreholes. Thesecond point is that such a study has been madeusing Isatis, with a particularly intensive use of thejournal files and the batch capabilities. It wasthus possible to run a sufficient number ofsimulations and scenarios in an efficient manner.... and still more to read onwww.geovariances.com/publications ...An article in spanish on “Estudio de SimulaciónCondicional aplicado al cálculo del espesor de lasobrecarga en un yacimiento de Nitrato y Yodo”.SQM NITRATOS S.A., CHILETRAINING AGENDACourses Description, Bookings: www.geovariances.comMore info: training@geovariances.comApplied Mining Geostatistics November, 18-22, 2002Keywords: Variography, Kriging, Multivariate, Grade Control, Ore ReserveEvaluation, Spatial Behaviour of the Mineralisation, Dispersion and Support.Workshop on Mining Geostatistics November, 25-29, 2002Keywords : Geostatistical Study, Own Data Set.Available upon request:Advanced Mining Geostatistics (5 days)Keywords : Multivariate Variography, Grade Control, Ore Reserve Evaluation,Spatial Correlation, Non-linear Geostatistics, Support & Information Effect,Grade Tonnage Curves.Géostatistique minière appliquée (5 jours)Mots Clés: variographie, krigeage, multi-variable, contrôle des teneurs,évaluation des réserves, comportement spatial de la minéralisation, support.IN PREVIEW, DISCOVER THE NEW FEATURES OF ISATIS V4.1• Variable Editor: a dedicated new application to edit variables of any fileo f t h e Isatis database. You can now modify their values withoutexporting your file outside I s a t i s .• Units Management: each length variable is now edited and used with itsown format. You will be able to create studies without variable scaling.• Copy Grid Files into Points Files: to transform a subset of a Grid Filedefined by a selection into a Points File. Macrovariables are handled.• Variogram Regularization: a n e w t o o l t o t r a n s f o r m a variogram model,established on points or small blocks, into the corresponding variogramfor a different block support size and orientation.• Batch Procedure: more flexibility in the batch procedures: loops may beintroduced in batch jobs while the user is continuously kept informed onthe action currently running. A journal file editor is also provided tomanage all the actions, a real improvement for the batch capabilities.• And others: o p t i m i z a t i o n o f t h e C P U t i m e i n T u r n i n g B a n d ss i m u l a t i o n s ; p u r e l y heterotopic covariances now can be correctly fitted.… Events …J o s é Terrones, our representative in Peru, will present a paper from JacquesDeraisme at INFOMINA 2002, 17-20 September in Lima, Perù.“Técnicas Geostadìsticas No Lineales para la Estimaciòn deReservas Recuperables : un Caso Pràctico ”.He will be pleased to meet you there at this occasion.Our consultants Jacques Deraisme and NicolasJeannée provide you with various services. Manyclients have already benefited from their skillsranging from software technical assistance toexpert advice. Why not you?For more information, please contactconsulting@geovariances.comor call+33 (0)1 60 74 90 93.49 bis avenue Franklin Roosevelt – BP91 – 77212 Avon Cedex, France – Phone : +33 (0) 1 60 74 90 90 – Fax : +33 (0) 1 64 22 87 28 – www.geovariances.com2900 Wilcrest, Suite 370 – Houston, TX 77042, USA – Phone : +1 713 782 8366 – Fax : +1 832 251 0586 – www.geovariances-americas.com