Design Optimization of Staged Fracturing for Long Lateral Horizontal Wells in Daniudi Gas Field

Hydraulic fracturing of horizontal wells in Daniudi Gas Field with long lateral section brings with it some problems such as multiple stages,serious interference among fractures,high fluid loss and severe damage due to long fracturing fluid retention time in formation,and long flow-back period,numerical simulation,laboratory experimental tests and other technical measures were used to optimize fracture parameters,fracture placement mode,staged fracturing process and operation parameters.In addition,method of synchronous gel breaking of fracturing fluid was developed.These constitute the optimization design technology for staged fracturing of horizontal wells with long lateral-section.This technology has been widely used in Daniudi Gas Field.21 horizontal wells with lateral-section length over 1 000 m were fractured in 2012.The fracturing results show that:no obvious interference was observed among staged fractures during post-frac production indicating fracture interval is reasonable;operation parameters match well with treatment success rate up to 100%;synchronous gel breaking of fracturing fluid is good;circulation loss reduced,flowback effect improved;natural flow rate after fracturing reaches over 50.0% and average gas production is 4.5×104 m3/d,a significant increment.Comprehensive analysis shows the optimization design technology for staged fracturing of horizontal wells with long lateral-section works well in improving the development of Daniudi tight sandstone gas field with extremely low permeability.