清洁转向酸在磨溪嘉二高压气藏水平井完井酸化中的应用

APPLICATION OF VISCOELASTIC SURFACTANT ACID IN HORIZONTAL WELL COMPLETION AND ACIDIZING IN SICHUAN MOXI JIAER HIGH PRESSURE RESERVOIR

针对磨溪嘉二气藏埋藏较深、高温、高压,水平井段长度大、有效储层分散及非均质的特点,成功用于磨溪雷一1气藏水平井完井酸化的连续油管拖动酸化工艺,由于受注入压力、管径的限制,施工排量、规模受限,不能完全满足嘉二气藏完井酸化的需要。新开发的清洁转向酸技术是依靠反应生成的盐类物质(CaCl2、MgCl2)的浓度及pH值的变化自然调节酸液的粘度,实现酸液的转向。达到封堵已酸化储层(高孔、高渗、裂缝性产层)的目的,从而实现非均质储层(长水平井段)的均匀酸化。该工艺技术在M005-H3井获得了成功应用,射后初测产气3.5706×104m3/d,采用加重酸解堵酸化后,测试产量减至2.61×104m3/d,采用清洁转向酸措施后气产量增至4.7888×104m3/d,采用胶凝酸重复酸化后产量又减至3.3366×104m3/d,表明清洁转向酸体系在该井的应用中具有明显的优势。

The characteristics of Moxi Jiaer gas reservoir are deep burial, HPHT, and long horizontal interval, disperse effective reservoir and heterogeneous lithology. The technology of coiling tubing pulling acidizing, which has been successfully used in horizontal well completion and acidizing at Moxi Lei-1 gas reservoir, can not completely meet the completion and acidizing requirements of Moxi Jiaer reservoir. The newly developed visco-elastic surfactant acid, dependent upon the variations of concentration and pH values of salts (as CaCl2 and MgCl2) generated in acid-rock reaction, automatically adjusts the acid viscosity, realizes acid diversion, thus seals off acid treated reservoir (high-porosity, high-permeability and fractured pay zone), and achieves uniform acidizing for heterogonous bed (long horizontal interval). This technology has been used successfully in well M005-H3. After perforation, the initially gas production rate is tested to 3.5706×104m3/d. After acid fracturing with weighted acid, the gas production rate reduces to 2.61×104m3/d. After acid treatment with visco-elastic surfactant acid, the gas production rate increases to 4.7888×104m3/d. And after reacidizing with gelling acid, the gas production rate reduces to 3.3366×104m3/d again. Above tests indicate that visco-elastic surfactant acid system has an obvious superiority in this well.