In seismically active regions, three groups of time-dependent phenomena influence each other and their interrelationship may be used to formulate a methodology for the prediction of variations in their characteristics. Upward gas mobility depends on the distribution and geometry of vertically and subvertically oriented fractures, faults and their permeability, which depends on their width, formation and rock pressure, and history of seismic-tectonic processes in the region of study. On the other hand, probability of earthquakes is also linked to the rock pressure and conditions at the faults' surfaces. In turn, earthquake occurrence may lead to changes in formation pressure and to fluctuation of conditions along surfaces of fractures and faults. Subsidence causes formation of vertically and subvertically oriented fractures in the geologic section above oil and gas fields. Formation of these fractures, in turn, may cause an increase in upward gas mobility. Joint monitoring of seismic activity, surface manifestations of upward gas mobility, and subsidence of the upper parts of the geologic section may lead to new methods for the control of possible upsurge of ps leakage. Measurements of subsidence and surface gas leakage may lead to new criteria for indication of increased earthquake possibility. Currently, a combined neural net based prediction of upward gas mobility, ground subsidence, and seismic activity in seismically active regions is under development by the authors.
