Вертикальная трещиноватость как особенность геологического разреза левобережной части АГКМ, влияющая на обводнение эксплуатационных скважин

Abstract

The left-bank part of the Astrakhan gas condensate field (AGCF) is represented by a carbonate reservoir of a complex type. The study of the geological structure and properties of the deposit is a fundamental factor for its successful operation. There are presented the main characteristics of the lithological composition and filtration-capacitance properties of the carbonate productive reservoir C2b of the left-bank part of the AGCF, described the specific features of their formation. One of the important features of the productive carbonate reservoir of the left-bank part of the AGCF is the anisotropy of filtration-capacitance properties in different directions. Special attention was paid to the description of horizontal and vertical fracturing, and post-sedimentation processes. There is proposed a probable mechanism of fracturing in areas of high occurrence of productive strata. The problem of well flooding is of great importance for the development of AGCF. Different factors of geological and technical order were investigated (the position of drilled faces and perforation intervals/open barrel relative to the position of the gas-water contact). No regularities were revealed. Based on the study of field data, zones of vertical fracturing have been identified, which caused the flooding of wells. It is possible to map watering zones according to the structural parameters of Bashkir deposits at the highest roof marks. There has been suggested a probable model of well flooding in the left-bank part of the AGCF associated with the tectonic factor and post-sedimentation processes of external influence. The actual data are presented, including a diagram of wells with a water-gas factor WGF ≥ 100 cm3/m3 depending on the occurrence of the roof C2b, which clearly confirm the predominance of a crack-pore collector with significant communication in the described zones.