The Research Of Fracturing Technology In Fracture Sandstone Reservoir

As the exploration of Wenmingzhai-Weichen-Hubuzhai area proceeded, the Triassic fractured sandstone reservoir was discovered, whose explored and controlled reserves reached 551.55×104t.For the compaction and low permeability of this sand reservoir, fracturing is needed for wells in this area. Among the 33 fracturing wells, 6 wells have the problem of sand plug, 3 wells have a low sand injection volume. By analyzing thses failures, the reasons are: first, the natural fractures are well developed, fluid loss is serious, instead of a main effective fracture, and multi-branched fractures are formed; second, the poor condition of barrier causes the fracture height extension out of control, the narrow and short hydraulic fracture raises the difficulty of pumping sand and causes sand plug.Aimed at the problems of fracturing in sandstone fractured reservoir, the performance of low damage fracturing fluids and their additives had been evaluated, the volume of gelling agent, crosslinker, fluid loss agent, surfactant, stabilizer had been optimized, low damage fracturing fluid system for different temperature had been successfully developed. Experimental evaluation shows that this fluid system has features of good temperature resistance, easy to break, no residue, small formation damage and good stability. Integrated with fluid loss control technology, quickly flowback technology, forced fracture closure technology and related perforation technology, a systematic fracturing technology for Wenmingzhai-Weichen-Hubuzhai Triassic fractured sandstone reservoir is developed.This technology had been applied more than 20 wells in this area. The success rate and effective rate of fracturing reached 95.0% and 88.9%, respectively. The average sand concentration is 27.1%, and the oil production of a single well is averagely increased 773 t. The field tests showed significant stimulation effects and extremely broad application prospect.