Fluid Production and Injection Induced Stress Changes Using Reservoir Volume Changes Inverted From Tiltmeter-Based Surface Deformation Measurements

Abstract

AbstractProduction and injection induced stress changes are in some circumstances, an important issue in field development and reservoir management. Previously, induced poroelastic stresses have been calculated by integrating the center of a dilatation source over a certain reservoir region.1,2 However, this approach has difficulty when the observation points lie inside the reservoir blocks. This paper presents the application of an analytical stress solution due to an initial (eigenstrain or transformation) strain in a cuboid3 to calculate the induced stress changes using the volume changes inverted from the tiltmeter-based surface deformation measurements.4,5 Arbitrary strain volumes can then be constructed from an assemblage of discrete cuboids, allowing stresses both within and outside the strain zone. The stress calculation formulation was applied to a field case study where a warm-up phase of steam injection into a steam assisted gravity drainage (SAGD) well pair was monitored with an array of surface tiltmeters and a downhole microseismic array6. Using a Mohr-Coulomb failure criterion, predicted locations of failure are compared with the actual locations from the microseismic monitoring.