Research on Middle Phase Micro-Emulsion Technology for Ultra-low Permeability Reservoirs

Abstract In response to prevalent issues such as suboptimal reservoir properties, inadequate formation energy, and challenges in water injection and fluid extraction in ultra-low permeability oil reservoirs located in the Jiyuan area of the Ordos Basin. Through the evaluation of performance, visual etching model tests, and field application assessments of the meso phase micro emulsion oil displacement system, aimed to explore new technologies for pressure reduction and injection enhancement in ultra-low permeability reservoirs. This approach seeks to expand the swept volume of water flooding and enhance oil recovery. The results show that: the mesophase micro-emulsions possesses a stable small particle size (20∼80nm), exhibits a strong ability to penetrate matrix pores, demonstrates a pronounced wettability reversal from neutral weak oleophilic to weak water wetting, and displays reduced inter-facial tension performance (10 −2 ∼10 −3 mN/m). Visual etching model test is used to analyze the injection parameters of micro-emulsions, micro displacement mode, viscosity reduction ability to improve the fluidity of crude oil and micro remaining oil occurrence state. Meanwhile, the utilization of meso phase micro emulsion in G83 reservoirs significantly diminishes the wellhead injection pressure and enhances the individual oil well productivity. This paper comprehensively examines the mechanisms of depressurization, injection enhancement, and improved oil recovery associated with medium-phase microemulsion flooding in low-permeability reservoirs. It covers aspects such as depressurization and injection increase, water drive enhancement, imbibition and energy augmentation, reservoir protection, and the practical implications of improving crude oil viscosity and fluidity, as well as effective production from micro nano pores in mesophase micro-emulsion. This provides theoretical support for ongoing research on efficient development of ultra-low permeability reservoirs and enhancing crude oil recovery.