Change in reservoir parameters in connection with the operation of deposits and underground gas storage facilities (by example Garadaghfield, Azerbaijan)

In the article, an analysis of the results of the study of the problem of deformation changes in rocks associated with the development of oil and gas fields and the operation of underground gas storage facility (UGS)was analyzed using the example of the Garadagh deposit / UGS in the South Caspian basin (SCB), taking into account world achievements. Based on repeated geophysical studies of wells, it was established that in the relatively short observation period (from 8 months to 2.5 years), the development of the VII horizon of the productive stratum (lower Pliocene) of the Garadagh gas deposit of the South Caspian Basin resulted in a decrease in rock permeability in the range from 1.2 to 4.9 mD at a pressure drop from 2.4 to 11.7 MPa. The relative decrease in permeability varies from 41 % to 56 %, the higher values of which are characteristic of highly porous rocks. It is shown that multiple cycles of changes in loads on the reservoir during the operation of the UGS also contribute to the development of deformation changes in the rock that lead to the destruction of the rock skeleton. Obvious evidence of objectivity of this process is the settling in the separator and the reservoir for liquid at the Garadagh UGS facility at the end of each season about 25-30 tons of sand, which is the product of the destruction of the underground reservoir rocks. This leads to irreversible changes in properties of the reservoir rocks, which are more contrastingly reflected in the change in rock permeability. Deformational changes in the formation caused by exploitation of deposit and UGS lead to reduction of productivity and injectivity of wells.