某铜矿难崩矿体水力压裂试验与效果评价

Hydraulic Fracturing Test and Its Effect Evaluation of a Difficult-to-Collapse Ore Body in a Copper Mine

针对某铜矿难崩矿体的水力压裂可行性,开展了岩体压裂物模试验。采用数值模拟方法研究了不同簇间距、不同施工排量、不同施工规模工况下压裂裂缝扩展,进行了地表裸眼和射孔两种压裂工艺的水力压裂工业试验和监测。试验结果表明:矿体可压裂性较好,具备形成多条复杂裂缝的条件;数值模拟结果表明,水力压裂施工排量在4~5 m^(3)/min范围内,单段液量主体为200~450 m^(3)时,能够满足40~70 m裂缝半长的需求,并可形成复杂裂缝网络;工业试验的两井水力裂缝在矿体短轴方向上延伸偏短,整体上符合延伸规律,基本达到设计要求;相比于裸眼井压裂,射孔井压裂由于采用多簇射孔+暂堵转向(孔眼+缝内),形成的水力裂缝更密集,监测到的缝长明显比设计的缝长短。研究结果为该矿山自然崩落法采矿的压裂诱导提供了依据。

A rock fracturing material model test was conducted to investigate the feasibility of hydraulic fracturing for a difficultto-collapse ore body in a copper mine.Numerical simulations were applied to investigate fracturing crack propagation under various cluster spacing,construction displacements,as well as construction scales and working conditions.Industrial hydraulic fracturing tests and monitoring were conducted for two types of fracturing processes,including surface open-hole and perforation.The results indicate that the ore body has a favorable fracturability,possessing the potential to form multiple complex fractures.The numerical simulations show that a hydraulic fracturing construction displacement is within the range of 45-m^(3)/min and a single-stage fluid volume of 200-450m^(3) can meet the demands of fracture half-lengths of 40-70m,resulting in complex fracture networks.The hydraulic fractures of two wells in the industrial test extend relatively short in the short axis direction of the ore body,which overall conforms to the extension law and basically meets the design requirements.Compared to open-hole fracturing,perforation fracturing uses multiple clusters of perforation and temporary plugging turning(perforation+internal fracture),resulting in denser hydraulic fractures,and the monitored fracture length is significantly shorter than the designed fracture length.The research results can provide a basis for the fracturing induction of natural caving mining method in this mine.