Geologic Factors Affecting Stress And The Relationship To Gravity

Hydrocarbons generation affects stress in the subsurface

Oil and Gas reservoirs are sealed traps of porous rocks in the subsurface. Hence, the reservoirs always have a different gradient than the normal stress gradients. Hydrocarbon expansion due to thermal cracking of kerogen (required temperature of 70ºC) or conversion of oil to gas (required temperature of 170º C) further increases the stress differential.

Reservoir development affects stresses in the subsurface

Tectonic forces due to the collision of tectonic plates and their movement cause abnormal pressures within subsurface. The trapping of buoyant hydrocarbons cause the reservoir rocks to experience stress fluctuations. These fluctuations are detectible as anomalies from the background tectonic stress.

Stress causes gravity variations

Stress and its effects on gravity field is a very new area of analysis. More recently, Hayes et. al., 2008 explained that gravity gradients may help researchers the ability to map the actual Coulomb stress changes by using gradients as a proxy to stress changes. They explained their solution for a vertical strike slip fault.