3 D inversion of borehole gravity data using cokriging

Borehole gravity has been used in mineral exploration recently with the advent of slim- hole gravime- ters． It is logical to perform inversion to utilize the information in the newly acquired data． The inversions were carried out by using cokriging，which is a geostatistical method of estimation that minimizes the error variance by applying cross- correlation between several variables． In this study the estimated densities are derived by using boreholes gravity and known densities along the borehole． This method does not need iterative process and computes efficiently． The selection of examples demonstrates that this method has the ability to include physical property from borehole measurements in the inversion． The synthetic examples demonstrate the density variation along a borehole can be well determined without depth constraints in the inversion． The resolution of the reco- vered model can be further improved by including the densities along the borehole for inversion． However，this capability decreases dramatically with the increasing of distance between the anomalous body and the borehole．