Geophysical processes and biosphere: article

Аnnotation: A review of anomalous subsidence (more than 1 m) of the Earth's surface at long-developed oil and gas fields measured in different regions of the world is presented. It is shown that the overwhelming majority of cases were obtained at oil fields. Anomalous subsidence of the earth's surface (about 1 m) was found only at one gas field. This is an unexpected result. Usually, the development of oil fields is accompanied by fluid injection, which should reduce the amplitude of subsidence. At gas fields, fluid injection does not occur, and this should contribute to the accumulation of large amplitudes of subsidence. Two paradoxes are formulated: large subsidence in oil fields and small subsidence in gas fields. Geomechanical models for explaining these paradoxes are presented. It is shown that to explain the paradox of large subsidence, it is necessary to consider the processes of destruction of reservoir rocks during periodic injection of liquid into the formation. The paradox of small subsidence in gas fields is due to the need to take into account the initial stress-strain state of the deposit and the dynamics of mechanical properties of rocks (porosity, compressibility) over the entire period of development.