Factors Controlling Stress Perturbations in Faulted Reservoirs – Insights From Numerical Parameter Studies

Tectonic stresses affect the optimal exploitation of reservoirs in numerous ways. The stress field, however, can vary locally in magnitude and orientation due to faults or changing lithologies. In order to minimize exploration risks and optimize drilling, a reliable, ideally “pre-drilling” prediction of the local in situ stresses is therefore desirable. The paper presents numerical parameter studies, which aim on the identification of factors controlling stress perturbations in faulted reservoirs. Data from the Rotliegend gas field Nord Hannover in Germany is used for the study. Modelling comprises building of 2D and 3D finite element models describing a typical fault block geometry of the reservoir selected. A default model is configured representing the recent state of the reservoir. Subsequently, various parameters like fault friction, size, magnitude and orientation of the maximum horizontal stress are changed systematically. These parameter studies suggest that the friction coefficient of faults, the mechanical properties and the angle between SHmax and the faults have the relatively largest influence on the development of stress perturbations.