关键词: 尕斯库勒油田E₃¹油藏, 隔夹层, 物性, 孔隙结构, 注气突破压力

Abstract: Aiming at the urgent need for EOR replacement technology after water flooding in continental low-permeability sandstone reservoirs with interlayers, comprehensively using the methods such as core observation, thin section analysis, scanning electron microscopy, mercury injection, breakthrough pressure experiments, this paper studies the types and characteristics of interlayers in the Gasikule E₃¹ reservoir, clarifies the law of breakthrough pressure during gas injection, and analyzes the enhanced oil recovery strategy for gas injection in reservoirs with interlayer development. Studies have shown that argillaceous and calcareous interlayers mainly develop in Gasikule E₃¹ reservoir, dominated by the argillaceous interlayers. There are few calcareous interlayers. The permeability of the interlayer is mostly less than 0.01 mD. Compared with the reservoir, the interlayer has extremely poor physical properties and pore structure, as well as nanometer-scale pore throats and low percolation capacity. Under the same condition of saturated medium, the breakthrough pressure gradient has a power exponential relationship with the permeability. The interlayer has strong longitudinal isolation ability, and the average breakthrough pressure gradient of the argillaceous interlayer is 103 to 491 times that of the reservoir. Gas is easy to selectively displace crude oil. Under the same core condition, the breakthrough pressure gradient is the largest after water saturation, which is 2 to 4 times that after oil saturation. The interlayer divides the reservoir into multiple flow units, effectively suppressing gas overlap and expanding the swept volume of gas, which is conducive to enhanced oil recovery through gas flooding after water flooding in continental low-permeability sandstone reservoirs.

Key words: Gasikule E₃¹ reservoir, interlayer, physical property, pore structure, gas breakthrough pressure of gas injection