Further development of a mathematical model to simulate the natural fracturing of rocks in oil and gas bearing chalk reservoirs. 3D finite element analysis. Status report.

摘要

An advanced three-dimensional finite element program, ABAQUS, has been implemented and used in a number of different connections at the Danish Gjeotechnical Institute. DGI also disposes over the requisite hardware capacity for calculations of rather detailed, spatial finite element models. This report illustrates by examples a selection of the possibilities of finite element simulation of the geological development as well as the development of the stress and strain conditions of an oil reservoir in the Danish part of the North Sea. One calculation was performed under completely drained conditions, i.e. pore pressure not taken into account. The calculation was carried through to the planned final state, simulating the development of the field for the last some 1.7 million years. Another calculation was performed based on consolidation theory, i.e. pore pressure taken into account. An initial state was produced by means of a partly executed calculation corresponding to the conditions some 1.7 million years ago. This initial state could be used for the continued final calculation. The main result of the calculations is a realistic stress/strain field in the simulated reservoir, being a useful starting point for simulating the future production potential to the field. (AB).