DEVELOPMENT METHOD OF TIGHT OIL RESERVOIRS BY CYCLIC PUMPING OF CARBON DIOXIDE Russian patent published in 2017 - IPC E21B43/18 

FIELD: oil and gas industry.

SUBSTANCE: method includes the cyclical increasing and decreasing of the operating agent pumping pressure in the injection wells, the application of the carbon dioxide as the operating agent, and the selection of products from production wells. Initially, choose the reservoir section with the permeability spreading from 0.001 mD to 2 mD, with the centrally located injection well and the current reservoir pressure equal to (0.5-0.8)·P (beginning). CO₂ injection is carried out through corrosion-resistant pipes with the gradual increase of the flow rate in the injection well from zero to the value, at which the injection pressure is equal to (0.7-0.9)·P (rocks). At the same time, the bottomhole pressure in the production wells is increased from the pressure of oil saturation with the hydrocarbon gas up to the current reservoir pressure, at which the liquid inflow to the wells is stopped. After that, the gas flow rate is reduced to the value, at which the injection pressure is equal to P (beginning). The bottomhole pressure is reduced up to P (present) in the production wells during this time. The gas injection cycles are repeated until the current reservoir pressure is restored up to (0.9-1.1)·P (beginning). After the cycles are completed, the injection of CO₂ is stopped, the production is carried out through the production wells at the bottomhole pressure above P (present) of oil, CO₂ or the hydrocarbon gas.

EFFECT: method allows to increase the oil recovery coefficient of tight oil reservoirs due to the complex application of cyclic carbon dioxide injection and the regulation of the production wells operating mode.

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