Resumo

JIMENEZ, Rosa  e  BOSCH, Miguel. Geostatistical inversion of gravity and well-log data. Rev. Fac. Ing. UCV [online]. 2008, vol.23, n.2, pp.71-81. ISSN 0798-4065.

We developed and applied a gravimetric inversion methodology that combines well-log and gravity information in a geostatistical framework. This technique looks for the optimal model that explains the geophysical data and satisfies the prior information on the model parameters, by solving iteratively a system of linear equations to update the 3-dimensional mass density field and the interface geometry between model layers. The optimal model jointly explains the gravity observations, complies with the prior statistical distribution of the mass density and honors well constraints on the interface between layers. We apply the technique to a set of data in eastern Venezuela to analyze the prediction errors on the sedimentary basin basement depth, and particularly the effect of progressively including more well constraints into the geostatistical inversion. The inversion process combining gravity and well data always produced a better prediction of the basement depth than the gravity inversion with no well control on the basement. We compared the basement depth estimates of the geostatistical inversion with the results obtained from plain interpolation of the well data (e.g. Kriging) and found that the geostatistical inversion of gravity data with well constraints improved the basement estimation when the spatial distribution of the wells is scarce, and both methods are equivalent when the spatial distribution of the wells is dense.

Palavras-chave : Inversion; Gravity data; Orinoco belt; Well-long data; Geostatistics.