3D Acid Fracturing Technology in Maokou Formation of Well Jinghe 1 in Southwestern Sichuan

Wufeng–Longmaxi Formation is the main shale-gas production horizon in southwestern Sichuan, and good gas indication shows in Maokou Formation in logging data from wells drilled through. To make a confirmation of the gas potential of the formation, Well Jinghe 1 was drilled as a preliminary prospecting well. In light of the short effective acidizing distance and limited stimulation volume from acid fracturing in Maokou Formation of an adjacent area, the fracture and pore development characteristics of the drilled strata in Well Jinghe 1 were analyzed. A three-dimensional (3D) acid fracturing technology was researched from the aspects of full 3D fracture propagation, the acid fracturing fluid system, and supporting operation parameters. The research results show that fine sectioning by multiple packers accompanied by large-displacement can reach the stimulation effect aiming at realizing connection of fractured bodies. The three-stage alternative injection of fracturing fluid and gelled acid can increase the stimulation volume of fractured bodies and the distances of acid etched fractures. This can met the requirement of deep penetrating and non-uniform etching in the horizontal direction as well as the high production of fine sections in the vertical direction. The production of Well Jinghe 1 was 12.52×10⁴m³/d after 3D acid fracturing, which was 38% higher than that with prepad acid fracturing. The post-fracturing fitting results indicated that fractured bodies were well connected. The successful application of 3D acid fracturing technology in Maokou Formation of Well Jinghe 1 provides a new idea for the development of gas reservoirs in Maokou Formation, Qixia Formation, and Dengying Formation in southwestern Sichuan.