Research and application of acid fracturing techniques in heterogeneous abnormal high pressure gas reservoirs in Talimu Basin

On the basis of summarizing the research achievements and application results of acid fracturing techniques used for the heterogeneous abnormal high pressure gas reservoirs in Talimu Basin in recent five years, a set of matching acid fracturing techniques have been formed for the reservoirs. They are: abnormal high pressure gas reservoir extreme overbalance perforating-alcohol- base retarded acid acidizing joint operation technique, heterogeneous gas reservoir viscous temporary plugging acidizing technique, low-permeability gas reservoir massive fracturing technique and hydraulic fracture cleaning technique. The extreme overbalance perforating-aciding joint operation technique was studied and applied to the naturally fractured abnormal high pressure gas reservoirs with severe mud filtration damage) through laboratory dual core flowing test and on-site application, the novel and effective viscous temporary plugging acidizing technique to the heterogeneous superdeep high-temperature gas reservoirs; and the massive sand fracturing technique to the abnormal high pressure superdeep low-permeability gas reservoirs. Meanwhile, an alcohol-base acidizing fluid system was developed, by which the fracture pollution caused by the fracturing in reservoir was successfully removed. Through these techniques' being applied on the spot, it was indicated that the individual well productivity of reservoir was greatly raised, petrophysical cutoff was lowered, and gas recoverable reserves were increased, thus providing an important technical support for the exploration and development of the abnormal high pressure superdeep gas reservoirs in the region.