哈法亚油田孔隙性石灰岩储层酸压先导性试验

中东地区哈法亚油田的Mishrif油藏为强非均质性整装背斜油藏，在构造边部进行酸压先导性改造试验过程中，受边底水影响，改造规模有限；储层岩石岩性纯不利于酸压过程中酸液的非均匀刻蚀；杨氏模量低，应力隔层遮挡能力较差，不利于缝长的延伸和缝高的控制；酸岩反应后原油乳化问题严重不利于返排。数值模拟和实验结果表明:针对储层特点，采用多级交替注入酸压工艺，优化注入工艺参数，能够增加酸岩反应作用距离，实现非均匀刻蚀；采用纤维暂堵降滤、互溶剂破乳助排配套技术，解决了压裂过程中酸液滤失大和压后返排困难的难题，最后阶段的闭合酸化增加了井筒附近的导流能力。优选了“交联压裂液+胶凝酸”的液体体系有效延缓了酸压反应速率，在现场MF3井取得了很好的应用效果，有效酸蚀缝长达到80 m，单井测试日产油达到317 t/d，储层改造效果显著。该研究为中东地区此类储层动用提供了有效的工程技术手段。

Acid fracturing pilot in the porous limestone reservoirs of Halfaya Oilfield

The Mishrif oil reservoir in Halfaya Oilfield of the Middle East is a monoblock anticlinal oil reservoir of strong heterogeneity, and its stimulation scale is limited due to the influence of bottom water when the acid fracturing pilot is carried out at the edge of the structure. The reservoir rocks are lithologically pure, which is not beneficial to the nonuniform acid etching in the process of acid fracturing. The Young’s modulus is low and the shielding capacity of stress barriers is poorer, which are not beneficial to the extension of fracture length and the control of fracture height. The crude oil is emulsified seriously after the acid/rock reaction, which is not beneficial to the flow back. Numerical simulation and experimental results show that the adoption of acid fracturing technology of multi-stage alternating injection and the optimization of injection technological parameters base on reservoir characteristic can increase the operating distance of acid/rock reaction and realize nonuniform acid etching; the support technology of fiber for temporary plugging and fluid loss control and mutual solvent for emulsion breaking and flow back promotion address the problems of great fluid loss in the process of fracturing and difficult flow back after the fracturing; and the closed acidizing in the last stage enhances the flow conductivity near the well. The “crosslinked fracturing fluid+gel acid” system is selected, which slows down the acid/rock reaction velocity effectively. Its application effect in Well MF3 is excellent. The length of the effective etched fractures is up to 80 m and the tested oil production rate of single well is 317 t/d, which indicates remarkable reservoir stimulation effect. The research results provide the effective engineering technology and method for the production of similar reservoirs in the Middle East.