Stochastic inversion of a gravity field on multiple scale parameters using surface and borehole data

摘要

A 3D stochastic inversion method based on a geostatistical approach is presented for three-dimensional inversion of gravity on multiple scale parameters using borehole density and gravity and surface gravity. The algorithm has the capability of inverting data on multiple supports. The method involves four main steps: i) upscaling of borehole densities to block densities, ii) selection of block densities to use as constraints, iii) inversion of gravity data with selected block densities as constraints and iv) down-scaling of inverted densities to small prisms. Two modes of application are presented: estimation and simulation. The method is first applied to a synthetic stochastic model. The results show the ability of the method to invert surface and borehole data simultaneously on multiple scale parameters. The results show the usefulness of borehole data to improve depth resolution. Finally, a case study using gravity measurements at the Perseverance mine (Quebec, Canada) is presented. The recovered 3D density model identifies well three known deposits and it provides beneficial information to analyse the geology of massive sulfide for the domain under study.