Stress distribution models in layered, viscoelastic sedimentary basins under tectonic and glacial loads

Abstract

SUMMARYKnowledge about the stress state in sedimentary basins gives insight into geodynamics of a given region, natural fracture development and is important in design of underground engineering operations, such as hydraulic fracturing. As the direct stress measurements are expensive, usually very limited amount of data is available, and the stress state assessment bases on theoretical models. In this work, we review the commonly used stress prediction models. We focus especially on the ones which take into account material viscoelasticity, and stress transfer between layers characterized by different mechanical properties. We extend the stress-driven elastic model to material viscoelasticity, and we apply it to predict stress changes during last glacial cycle in the Baltic basin, northern Poland. We conclude that neglecting material viscoelasticity in creeping rocks like shales or rock salt may lead to erroneous stress prediction, and that coupling of the layers induces stress transfer among layers, and together with stress relaxation in ductile layers may result in significant stress amplification in strong (elastic) layers. Finally, we emphasize the crucial role of initial stress assessment.