Investigating the electric properties of a siliciclastic reservoir based on rock-physics modeling and laboratory experiments

Abstract

This thesis is submitted for the Philosophy Doctor degree in Petroleum Geophysics at the Section of Petroleum Geology and Geophysics (PEGG), Department of Geosciences, University of Oslo. This study has been financially supported by the Research Council of Norway (NFR) and StatoilHydro within the framework of PETROMAKS (Programme for the Optimal Management of Petroleum Resources) through the project ‘Honoring the complexity of the petroleum reservoir- a new modeling tool for sea bed logging’. One of the main goals of the project has been to extend Controlled-Source EM (CSEM) forward modeling by including a proper electric rock-physics description of a hydrocarbon reservoir. An extensive conductivity model of reservoir rocks based on Differential Effective Medium (DEM) theory has been developed. It was integrated with both 1.5D and 2.5D CSEM forward modeling tools and the potential of this combined method to describe possible production effects of the CSEM response was demonstrated. A parallel work has been to modify a triaxial cell so that it can carry out simultaneous resistivity and acoustic measurements at reservoir conditions. A variety of such tests employing core samples have been carried out to calibrate rock-physics models and to gain basic understanding of the electric and elastic properties of reservoir rocks. The outcomes of this study are briefly presented in an introduction giving the background, main objectives and contributions made followed by three scientific papers (two published and one submitted) and four proceeding papers. The first paper focuses on the development of the DEM model and the second and third papers discuss the modification of the triaxial cell and the corresponding simultaneous resistivity and acoustic measurements on core samples. The first three proceeding papers discuss implementations of various rock-physics models within CSEM forward modeling tools and show the influence of rock properties on the CSEM response. The last proceeding paper compares the efficiency of different antenna types and orientations for detecting hydrocarbon layers employing CSEM.