Application of cross-linked acid-carrying sand fracturing technology to carbonate reservoirs

In recent years, in view of transformation of carbonate reservoirs, a variety of acid fracturing technologies taking deep acid fracturing as the focal have been developed both at home and abroad. At the same time, sand fracturing is tested by trial. Based on analyzing the shortcomings of acid fracturing and sand fracturing, the cross-linked acid-carrying fracturing technology is developed, according to the characteristics of the Lower Paleozoic carbonate reservoir in Changqing gas field. Cross-linked acid fracturing fluid features in high viscosity, low filtration, low friction, convenient pump delivery, slow acid-rock reaction, high efficiency in seam building, easy flowback, good rheological property, and good sand-carrying capability. So the target to achieve deep penetration of acid system, improve conductivity of etching cracks, extend the validity period after fracturing, and improve the single well capacity can be fulfilled. The technology has been used for the cross-linked acid-carrying sand fracturing test of carbonate reservoirs in Jingbian gas field successively since 2006. Statistics of 23 wells show that the success rate and efficiency of using the technology reach 100%. In the carbonate reservoir with similar physical property and gas bearing property, the average absolute open flow (AOF) reaches 13.791×104 m3/d after using the technology. While the average AOF of eight wells is only 9.745×104 m3/d after hydraulic fracturing. Te production is therefore increased a lot by using the technology.