Geophysical inversion using petrophysical constraints

Petrophysical information is sometimes available from well logs, laboratory measurements, etc. It has been shown that incorporation of such information into geophysical inversions can greatly improve the recovered models. However, when the known petrophysical information is not applicable throughout the entire region, the application of petrophysical constraints to geophysical inversions could seriously distort the resulting models. In this study, we propose a new inversion algorithm that is capable of building the petrophysical information into the inversion, while overcoming the aforementioned problem. The lithology differentiation is accomplished by applying fuzzy c-means (FCM) clustering algorithm to the models inverted from this new method. We illustrate this method with a synthetic crosshole seismic example and a gravity survey that measures both surface and borehole gravity response.