FEATURES OF DEVELOPMENT OF BASHKORTOSTAN OIL FIELDS IN CARBONATE SEDIMENTS

Abstract

The main oil reserves on the territory of Bashkortostan lie in terrigenous sediments. Intensive drilling and long development periods have led to the fact that oil reserves in terrigenous deposits have been significantly depleted. In the last decade, 80 % of the increase in reserves was provided by carbonate deposits. The share of remaining oil reserves in carbonate reservoirs has been steadily growing over the past 20 years and by the beginning of 2023 amounted to 32 %.The low efficiency of waterflooding of carbonate sediments and, at the same time, the achievement of high recovery factors with dense well patterns, characteristic of a water-pressure regime, are explained by the hypothesis put forward of the formation of vertical and inclined man-made cracks during the process of percussion-rotary drilling of wells.It is substantiated that when carrying out geological and hydrodynamic modeling it is necessary to take into account the presence of man-made cracks in vertical and inclined direc-tions and hydrodynamic connection through dense reservoirs with underlying water-saturated porous rocks. It is recommended to continue studying the influence of man-made fracturing in horizontal wells and in open-bottom wells on the technological indicators of the development of an oil facility.