Compaction of Ductile Reservoirs: Periodic Instabilities and Sand Production

Abstract

Geothermal reservoirs are characterized by high temperatures and unlike conventional petroleum plays have often long passed the threshold for ductile deformation of the involved minerals. In this environment traditional -brittle- concepts of failure and stimulation techniques have limited performance, usually short-lived. The reason for this is the nature of ductile deformation, with the rate of deformation (time) erasing brittle features in time. Hence, ductile reservoirs are prone to ductile instabilities, which in turn determine their stability and performance. In this study we summarize recent findings for shear failure and compaction instabilities under high temperature environments. We show that these reservoirs are formed by strong interactions of chemical reactions and long time scale creep processes and their geological fingerprint cannot be described by classical reservoir mechanics.