Study on Waterproof Lock Low Concentration High-Density Fracturing Fluid System and Its Field Application

Abstract

For water sensitive gas reservoir with high pressure in construction, the conventional fracturing fluid has some difficult problems, such as serious damage caused by water lock and high construction pressure, which seriously affect the gas well production. Using low damage high-density fracturing fluid with waterproof lock function as reservoir stimulate fluid is an effective measure to improve gas production of this kind of reservoir. Therefore, the research on the high-density fracturing fluid system with low concentration and waterproof lock function is carried out, including the selection of weighting agent, the research of waterproof locking agent, the optimization of low concentration fracturing fluid system, the evaluation of the adaptability of fracturing fluid to reservoir and the optimization of fracturing technology. The technology was applied in X well in Debei. The main fracturing scheme was continuous sand addition and crosslinked fracturing fluid. Crosslinked fracturing fluid was 680 m3, construction rate was 5–5.5 m3/min, proppant concentration was 385–328 kg/m3 and total proppant was 31 m3. The flowback rate after fracturing was as high as 82.5%. The construction pressure and friction are lower than that of conventional fracturing fluid, and the damage to reservoir caused by fracturing fluid is effectively reduced. The successful application of the well proves the feasibility and effectiveness of the waterproof lock low concentration high-density fracturing fluid system, and also shows that it has a good application prospect in water sensitive gas reservoirs with high operation pressure.KeywordsWaterproof lockLow concentration high-density fracturing fluidLow damageConstruction pressureFriction