深层碳酸盐岩储层有机酸深穿透酸压工艺

利用常规酸液体系对深层碳酸盐岩储层进行酸压改造时面临着酸蚀缝长短、导流能力递减快等问题。为实现这类储层的高效改造,对有机酸、胶凝酸等不同的酸液体系获得的有效作用距离及长期导流能力进行实验研究。对比不同酸液体系的酸岩反应动力学方程,可知相较于胶凝酸,有机酸有效作用距离能提高10倍以上,但有机酸在低闭合应力(10 MPa)和高闭合应力(60 MPa)下长期导流能力均低于胶凝酸液体系。为在实现酸蚀裂缝长有效缝长及高导流能力,提出了"有机酸+胶凝酸"注入方式,先用有机酸进行远端刻蚀,再用胶凝酸提高近井导流能力。并对典型井优化,得到施工排量8～10 m~3/min,施工液量850～950 m~3,施工段塞在2～3段能取得较好的酸压施工效果。

Research on Long Penetration Organic Acid Fracturing Technique in Deep Carbonate Reservoir

The use of conventional acid system for acid fracturing of deep carbonate reservoirs is faced with problems about short acid-etched fracture length and fast decreasing conductivity. In order to realize efficient stimulation of such reservoirs, the effective distance and long-term conductivity of organic acid, gelling acid and other acid systems were studied experimentally. Comparing kinetic equations of acid rock reaction of different acid system, it can be seen that the effective distance of organic acid can be increased by more than 10 times compared with gelling acid. However, long-term conductivity of organic acids under low closed stress (10 MPa) and high closed stress (60 MPa) is lower than that of gelled acid systems.An organic acid + gelling acid injection method was proposed to achieve long penetration fracturing, which was firstly etched with organic acid, and then gelled acid was used to improve the conductivity of the near well. Optimized for typical wells, the fluid displacement is 8~10m³/min, fluid volume is 850~950m³, and the plugging in the 2~3 section can achieve better acid fracturing effect.