ISATIS - Geovariances

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