Numerische Simulationen des Clay-Smear-Prozesses in Sandboxversuchen

Numerical Simulations of the Clay Smear process in sandbox experiments.

In the exploration, extraction and oil production, knowledge of the flow situation in the underground is crucial. In faulted zones, the flow process can be hindered due to the inclusion of clay in them, process known as clay smear. There are different approaches to evaluate the Clay Smear, which take into account the thickness of the initial situation and the fault offset, e. g. Shale Gouge Ratio (SGR). Based on the stated limits it can be estimated whether the clay inclusion in the fault could obstruct or seal the flow through it. Parameters of significant importance like the shear strength of the material and the stress level are not considered by the existing approaches.
In frame of an interdisciplinary research project between the Institutes of Geotechnical Engineering and the Structural Geology at the RWTH Aachen University, the Clay Smear processes are studied by linking fieldwork, sandbox experiments and numerical simulations.
In this paper the numerical simulation of the sandbox experiments are presented. By using these simulations the factors which influence the clay smear are indentified deriving a new calculation formula to evaluate the limits of the SGR. In this new approach the influence of the stress level, shear strength of the materials and kinematics are taken into consideration. The developed equation based on physical principles, offers the possibility of calibrating a model using the data from laboratory and field experiments.