Geophysical processes and biosphere: article

Аnnotation: The results of long-term repeated leveling observations with increased spatial-temporal detail (distance between benchmarks 0.3-0.5 km or less, intervals between measurements - 0.5-1.0 years) at oil and gas fields and underground gas storage in Russia and Turkmenistan are considered. Various forms of deformational consequences were found: weak general uplift or absence of subsidence of the Earthʼs surface within oil fields; absence of subsidence during long-term development of a gas field; cyclic deformations (rise and subsidence) during injection and withdrawal at underground gas storage; the presence of local subsidence in fault zones at all facilities, including the period of gas injection at the underground gas storage. Three-dimensional analytical models of deformations of the surface of a weightless elastic half-space in which prismatic poroelastic inclusions and inhomogeneities of mechanical properties (bulk elastic moduli) are located are constructed. To assess the final subsidence in oil and gas fields caused by a decrease in reservoir pressure, amendments to the solution for a weightless medium are proposed, taking into account the weight of the overlying rocks, the dynamics of changes in poroelastic parameters and the genesis of the formation of the field. It is shown that the use of a superposition of solutions on half-space displacements, containing inclusion and inhomogeneity, allows one to explain such paradoxical phenomena as the absence of subsidence during long-term development of a gas field and the presence of local subsidence under conditions of gas injection into an underground storage. The calculation results are compared with the data of repeated geodetic observations and the parameters of the development and operation of the underground gas storage and their consistency is obtained.