Integration of crosswell seismic data for simulating porosity in a heterogeneous carbonate aquifer

Abstract

A challenge for the geostatistical simulation of subsurface properties in mining, petroleum and groundwater applications is the integration ofwell logs and seismic measurements,which can provide information on geological heterogeneities at a wide range of scales. This paper presents a case study conducted at the PortMayaca aquifer, located inwesternMartin County, Florida, inwhich it is of interest to simulate porosity, based on porosity logs at two wells and high-resolution crosswell seismic measurements of P-wave impedance. To this end, porosity and impedance are transformed into cross-correlated Gaussian randomfields, using local transformations. The model parameters (transformation functions, mean values and correlation structure of the transformed fields) are inferred and checked against the data. Multiple realizations of porosity can then be constructed conditionally to the impedance information in the interwell region, which allow identifying one low-porosity structure and two to three flow units that connect the two wells, mapping heterogeneities within these units and visually assessing fluid paths in the aquifer. In particular, the results suggest that the paths in the lower flowunits, formed by a network of heterogeneous conduits, are not as smooth as in the upper flow unit.