关键词:

蓄能增渗, 压力规律, 数值模拟, 裂缝, 基质, 焖井, 提高采收率

Abstract:

A number of problems have been experienced with water injection in Yanchang Oilfield，such as high-pressure injection failure，poor flooding effect，and rapid increase of water cut during injection. An innovative method for energy charging and permeability enhancement is proposed to address these issues. Numerical reservoir simulation is used to study the evolution of fractures，matrix pressure，and bottom hole pressure propagation during injection and well shut in. The influence of injection volume on fracturing effect is also analyzed. It is found that，during the injection stage，rapid injection of fluid increases the pressure in the fracture，with the injected fluid passing through the main fracture to the tips of the fractures. The pressure increase mainly occurs around the fracture itself，with little change in the matrix pressure. In shut in stage，as shut in time increases，the matrix pressure in the fracture and near-fracture zone initially decreases rapidly and then tends to become stable after a certain time. If the distance from the fracture is more than 30 m，the matrix pressure first increases and then decreases with the increase of shut in time. The bottom hole pressure also declines rapidly in the early stage of shut in with the rate of decline slowing in the later stage. The greater the injection volume，the higher the formation energy. Analysis of the effect of energy charging and permeability enhancement in field applications for low permeability reservoirs shows remarkable increases in pressure and oil production. This provides a valuable reference for the development of energy charging and permeability enhancement in similar reservoirs.

Key words:

energy charging and permeability enhancement, pressure law, numerical simulation, fracture, matrix, shut in, enhanced oil recovery