Multistage Temporary Plugging Acid Fracturing Technology Application Long Interval Heterogeneous Carbonate Reservoir

Abstract Sichuan Puguang Gas Field is high sulfur content carbonate gas reservoir buried in the depth of 4775.4~6461.3m. In the produced gas, the average content of methane is about 75%, H2S 15% and CO2 10%. The thickness of producing formation is between 176.4m~838.8m, on average, the thickness is 395m. The formation is severely heterogeneous, including type?, type? and type ? reservoir which is developed alternately. The proportion of type ? reservoir is more than 50%, the total ratio of type ? and type ? is more than 90%. Gas testing in early exploration phase obtained no commercial gas production in type ? and type ? reservoir. Using the cores from Puguang gas field reservoir, fracture flowing capacity experiments have been conducted by using various acid fracturing fluid systems and different technical models. Considering geological characters, completion situation and surface gathering conditions, large-scale temporary plugging multistage injection acid fracturing technology is selected. The plugging ratio of the temperature-controlled temporary plugging agent is more than 90% and the plugging strength is greater than 15MPa. The pump discharge capacity of the new gel acid system is 10 m3/ min. The operating friction is 30% of that of clear water. The viscosity is more than 30mPa•s after being kept for 180min under 130?. 34 wells have been acid fractured by using this technology, and the average open-flow capacity of a single well is 487.8×104m3/d. And after having been producing for one year the average gas production of a single well is 69.3×104m3/d. Multistage temporary plugging acid fracturing technology application to long well interval heterogeneous carbonate reservoir integrated with acid fracturing technology and optimized design is technical guarantee to develop Puguang Gas Field efficiently and safely, and at the same time it will also be a technology backup to develop some similar gas fields.