Geomechanical-Data Acquisition, Monitoring, and Applications in SAGD

Abstract

Summary Steam-assisted gravity drainage (SAGD) has proved to be a commercially viable method to extract bitumen from oil-sands reservoirs in western Canada. To understand the influence of steam injection on reservoir and surrounding rocks and potential impacts of surface deformation on the environment, various types of instrumentation and 4D-seismic surveys have been applied in SAGD projects. The effect of geomechanics on SAGD has been well documented. Collecting essential geomechanical data, properly interpreting them, and incorporating them into numerical models are necessary to ensure meaningful history matching and understanding of reservoir performances. This paper outlines geomechanical-data acquisition and field-monitoring methods from a reservoir-engineering perspective, and the applications of geomechanics in SAGD analyses. Minimal-data-acquisition programs are suggested to collect the necessary geomechanical data for different analysis purposes in SAGD projects. Primary instrumentation is briefly overviewed, and recommendations for instrumentation selection are provided. Using generic Canadian-oil-sands reservoir and rock properties, the subsurface and surface changes and deformations are simulated, including permeability changes, reservoir movements, and strains and surface uplifts. Simulations are completed with a widely applied thermal simulator, and its limitations are also discussed. The method to couple the results of geostatistics modelling, reservoir simulation, and geomechanics in SAGD simulation and to link them with a 4D-seismic survey in history matching is provided.