大牛地气田长水平段水平井分段压裂优化设计技术

针对大牛地气田长水平段水平井压裂段数多、缝间干扰严重、压裂液滞留地层时间长且滤失量大、对地层伤害大、排液周期长等问题，采用油藏数值模拟、裂缝模拟及室内试验等技术手段，优化了裂缝参数、布缝方式、分段压裂工艺与施工参数，研究了压裂液同步破胶方法，形成了长水平段水平井分段压裂优化设计技术。该技术在大牛地气田进行了广泛的现场应用，盒1层21口水平段长度超过1 000 m的气井压裂结果表明:裂缝间距优化合理，后期生产没有出现明显的缝间干扰现象；施工参数与地层匹配性好，工艺成功率100%；压裂液同步破胶取得明显成效，基本达到同步破胶的目的；降低了地层滤失，提高了排液效果，压裂后自喷排液率达到50.0%以上；压裂措施有效率100%，平均产气量4.5×104 m3/d，产量增幅明显。现场应用分析表明，长水平段水平井分段压裂优化设计技术可大大提高大牛地气田特低渗透致密砂岩气藏的开发效果。 

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.