Rock physics modeling with mineralogical inversion in sandstone reservoir

Abstract

Reservoir characterization is a valuable tool for the oil and gas industry. A better understanding of the reservoir demands the integration of petrophysical properties and elastic parameters. This integration is commonly performed with the aid of rock physics models. The elastic properties of solid-phase components are important parameters for rock physics models calibration. In this paper, we use an adaptation of mineralogical inversion to estimate the volumes of quartz, feldspar, and clay minerals that incorporate previously calculated clay volume and porosity. Clay volume estimation is performed from neutron and bulk density logs. We chose this method due to the presence of feldspar minerals in the reservoirs. Our workflow consists of petrophysics properties estimation, mineralogical inversion, rock physics model calibration in Well A, and compressional-wave velocity estimation in Well B. The mineralogical inversion in Well A provided average volumes of 64% quartz and 16% feldspar and previously estimated 20% clay minerals. When applied to Well B, the calibrated soft-sand model is a better approximation for high porosity data points than the constant-cement model, and the error between original and estimated logs is about 2.9%, suggesting that the approach can be extended to other wells in the study area.