Considering the characteristics of carbonate reservoirs in the Middle East, a low-viscosity microemulsion acid that can be prepared on site and has an appropriate retardation ability was developed. It was compared with four conventional acid systems (hydrochloric acid, gelled acid, emulsified acid and surfactant acid) through experiments of rotating disk, multistage acid fracturing and core flooding with CT scanning. The micro-etching characteristics and conductivity of fracture surfaces were clarified, and the variation of saturation field during water invasion and flowback of spent acid and the recovery of oil phase relative permeability were quantitatively evaluated. The study shows that the addition of negatively charged agent to the oil core of microemulsion acid can enhance its adsorption capacity on the limestone surface and significantly reduce the H⁺ mass transfer rate. Moreover, the negatively charged oil core is immiscible with the Ca^{2 +} salt, so that the microemulsion acid can keep an overall structure not be damaged by Ca^{2 +} salt generated during reaction, with adjustable adsorption capacity and stable microemulsion structure. With high vertical permeability along the fracture walls, the microemulsion acid can penetrate into deep fracture wall to form network etching, which helps greatly improve the permeability of reservoirs around the fractures and keep a high conductivity under a high closure pressure. The spent microemulsion acid is miscible with crude oil to form microemulsion. The microemulsion, oil and water are in a nearly miscible state, with basically no water block and low flowback resistance, the flowback of spent acid and the relative permeability of oil are recovered to a high degree.

针对中东碳酸盐岩油藏特点，开发了可现场配制、具有适当缓凝能力的低粘度微乳酸。通过转盘、多级酸压、CT扫描岩心驱油实验，与4种常规酸体系（盐酸、凝胶酸、乳化酸、表面活性酸）进行对比。明确了裂缝表面的微刻蚀特征和导流能力，定量评价了水侵和废酸返排过程中饱和度场的变化以及油相相对渗透率的恢复情况。研究表明，微乳酸油核中添加负电荷剂，可增强其在石灰石表面的吸附能力，显着降低H ⁺传质速率。而且，带负电的油核与Ca ²⁺盐不混溶，使得微乳酸能够保持整体结构，不被反应过程中生成的Ca ²⁺盐破坏，吸附能力可调，微乳结构稳定。微乳酸沿裂缝壁具有较高的垂直渗透率，可以渗入深层裂缝壁，形成网状蚀刻，从而大大提高裂缝周围储层的渗透率，并在高闭合压力下保持高导流能力。废微乳液酸与原油混溶形成微乳液。微乳液、油和水处于近混相状态，基本无水阻，返排阻力低，废酸的返排和油的相对渗透率得到较高程度的恢复。