SRV-oriented fracturing with viscosity-variable fracturing fluids in the Jin-30 well district, Dongsheng gas field

The He-1 Member, the main target of the Jin-30 well district of the Dongsheng gas field, is a tight sandstone gas reservoir with high heterogeneity. The hydraulic fracturing highlighting extended fractures is found with inferior reservoir stimulation performance. Under this background, the applicability evaluation of the stimulated reservoir volume (SRV)-oriented fracturing was performed, and the fracture propagation pattern was investigated using cores. The main control factors on the formation of complex fracture networks were clarified, and the fracturing treatment parameters were optimized via numerical simulation. The research showed that the He-1 Member reservoir of the Jin-30 well district is characterized by a high brittleness index, well-developed natural fractures and small horizontal principal stress difference, and therefore, complex fractures are expected in the case of fracturing using low-viscosity fluids and high pump rates. Moreover, the complexity of the resultant fracture network is high, and the SRV is rather expanded, under the conditions of the pump rate of 8−10 m³/min, injected liquid of 700−800 m³, the viscosity fracturing fluid combination of 10 mPa · s + 100 mPa · s, the proportions of prepad fluids of 50%−55% and the average proppant concentration of 20%−22%. The presented technology has been applied to 34 vertical/direction wells in the field. The average post-fracturing production reaches 1.85×10⁴ m³/d, representing an increment of 68.2%, compared with that of the fracturing technology targeting long fractures. This validates the high applicability of SRV-oriented fracturing with viscosity-variable fracturing fluids to the Jin-30 well district and applications of this technology should be further promoted.