缝洞型油藏雾化酸深部酸化机理研究

缝洞型油藏发育大量溶洞和裂缝、非均质性强，酸化施工时酸液会优先进入并扩大溶洞，影响蚓孔延伸。针对注气开发的缝洞型油藏，提出雾化酸酸化工艺，雾化酸可有效沟通不连续的缝洞储集体，形成有利的油气渗流通道。为明确雾化酸井筒稳定流动界限，采用雾状流井筒流动模拟实验，发现在20℃、标准大气压、60 m3/h的气体注入速度、20mL/min的液体注入速度、0.5%的十二烷基苯磺酸钠雾化稳定剂浓度下，雾状流最为稳定。通过酸岩反应动力学实验，发现在130℃、转速为110 r/min、初始酸浓度为15%时，常规酸酸岩反应速度为20.12×10-6 mol/（cm2·s），而雾化酸为1.87×10-6mol/（cm2 · s），比常规酸小一个数量级，雾化酸具有优良的缓速效果。未添加缓蚀剂时，常规酸对N80钢的腐蚀速率为572.16 mm/a，而雾化酸为40.08 mm/a，不及常规酸的十分之一，雾化酸对管柱缓蚀效果显著。 

Study on the Mechanisms of In-depth Acid Job of Atomized Acids in Fractured and Vuggy Reservoirs

Fractured and vuggy reservoirs are developed with large amount of karst caves and fractures, and are of high heterogeneity. During acidizing operation, acid fluids will preferentially flow into the caves and fractures, increasing the size of the caves and affecting the extension of wormholes inside the rocks. In this paper, an acidizing technique with atomized acids that can be used to effectively develop fractured and vuggy reservoirs is presented. Atomized acids can effectively communicate the disconnected fractured and vuggy reservoir spaces, helping form good oil and gas flow channel. To clearly define the boundary of stable flow of oil and/or gas in wells acidized with atomized acids, simulation experiments with mist flow were performed and it was found that the most stable mist flow can be obtained at the following conditions:20℃, standard atmospheric pressure, gas injection rate of 60 m3/h, liquid injection rate of 20 mL/min and concentration of mist stabilizing agent (sodium dodecyl benzene sulfonate) 0.5%. Kinetic experiment of acid -rock reaction showed that at 130℃, rotational speed of 110 RPM and initial acid concentration of 15%, the reaction rate of rock-normal acid was 20.12×10-6 mol/(cm2·s), while the reaction rate of rock-atomized acid was only 1.87×10-6 mol/(cm2·s), less than the reaction rate of normal acid by an order of magnitude, indicating that atomized acids have excellent retardation performance. The corrosion rate of normal acids to N80 steel is 572.16 mm/a, while that of atomized acids to N80 steel is only 40.08 mm/a, less than one tenth of the corrosion rate of normal acids, indicating that atomized acids are quite less corrosive to tubular goods than normal acids.