## 1 Introduction
(2020) [30] investigated the impact of quaternary ammonium salt-type clay stabilizers on the surface properties of clay minerals and observed that these salts could alter the hydrophilicity of clay mineral surfaces, reducing contact angles. Molecular deposition (MD) membrane oil-injection technology is a new type of tertiary oil recovery technology that not only fills the gaps of the two previous oil-injection methods but also has unparalleled features and advantages compared to traditional chemical injection [31; 32]: (1) In terms of oil recovery efficiency, water injection, polymer injection, and three-component composite injection mainly rely on displacement mechanisms, while membrane agent injection relies on imbibition mechanisms. The imbibition action of the membrane agent is more conducive to the initiation of residual oil in medium-sized and small pores. Therefore, the oil recovery efficiency of the MD membrane agent is higher than that of any previous agent. Moreover, MD membrane agent injection can further improve the oil recovery rate based on water injection, polymer injection, and three-component composite injection. (2) From the properties of the MD membrane oil-injection agent itself, the formation of the nanometer-level MD ultra-thin film is a self-assembly process that relies on the balance of static electrical interactions between the rock surface and the film-forming molecules without any external force. Moreover, the thermal stability and mechanical stability of the MD membrane are good; the MD membrane oil-injection agent has a low concentration and high oil recovery efficiency, and no alkali, surfactant, or other chemical reagents are needed, causing minimal damage to the reservoir; additionally, the MD membrane oil-injection agent has good anti-swelling effect and bactericidal ability; its surface activity is not high, and it will not cause the unfavorable influence of crude oil emulsification; the solution of the membrane agent is neutral, and it causes almost no corrosion to the injection or production system pipes or casings and does not harm the human body. There have been experimental studies on the molecular deposition film displacement mechanism, permeability characteristics, and other aspects conducted in laboratory settings [33; 34; 35; 36]. It has been observed that unlike conventional chemical agents, the membrane agent system has minimal impact on the interfacial tension between oil and water as well as the viscosity of crude oil. However, there is a significant adsorption amount and rate of membrane agent molecules in the rock core, indicating that the molecular deposition film displacement mechanism differs from traditional chemical displacement methods such as polymer flooding, surfactant flooding, alkali flooding, and composite flooding [12; 37; 38]. This method utilizes a water solution as its transmission medium, with membrane agent molecules relying on electrostatic interactions for film formation. The effective molecules of the membrane agent deposit onto negatively charged rock surfaces to form nanometer-thick ultra-thin films that alter reservoir surface properties and interaction states with crude oil by reducing adhesion between crude oil and rock surfaces. The current reservoir pressure in the Da'anzhai formation in the study area is low, with significant degassing and an accelerating production decline rate. The recovery rate is less than 6%, and the effectiveness of water flooding technology application is poor. Based on the molecular deposition film mechanism of enhanced oil recovery, research was conducted to optimize the concentration of molecular deposition film injection and simulate cyclic oil recovery experiments. A quantitative evaluation of the impact of molecular deposition film drives on reducing driving pressure, improving permeability, and increasing oil recovery rate in low-permeability reservoirs was carried out.