Geothermobaric features of Borysivsky field and their consideration in gas reserves calculation

Abstract

Borisivsky gas condensate field is situated at the northern edge of the Dnieper-Donets basin. Both elision and thermodehydration sections are involved in the lower hydrogeological floor (stage) of the field’s cross-section according to the vertical hydrogeological zoning. As a result, differences of reservoirs’ pressure aspects are observed in the sections. Deep fluid reservoirs are characterized by abnormal reservoir pressure and another hydrogeological parameters change much as well. Estimation of gas reserves as example was used to show how initial temperature-pressure conditions were defined in reservoirs. Graphic-analytical method of mid-reservoir gas pressure calculation is based on the fact that the reservoir pressure and the water drive system pressure at the gas-water contact are the same. Therefore, it is necessary to know distribution of the water drive system pressures around the field. If data of measured pressure are available, the mid-reservoir pressure can be calculated by the barometric formula.

The definition of initial temperature and pressure conditions of the horizon V-19 showed that both the standard graphic-analytical method and calculated by the barometric formula can be used. Furthermore, these methods do not lead to large errors in the definition of the initial pressure in the reservoir, for the residual thickness of sedimentary strata in the thermodehydration section at the northern edge does not contribute to the formation of reservoirs with abnormal pressure, and gas-water contacts can be located at the basement.