基于阿基米德双螺旋线原理的水力喷射压裂技术

针对水平井多级压裂双簇水力喷射效果不佳、上下游喷射器冲蚀不均匀和水平井筒内携砂流体中砂粒易沉降等问题，研究了基于阿基米德双螺旋线原理的水力喷射压裂技术。根据阿基米德双螺旋线原理，设计了双螺旋水力喷射压裂管柱及喷射器，并采用可视化试验方法对双螺旋特性进行了室内携砂评价试验；根据牛顿第二定律建立了水力喷射压裂工况下等径直管和双螺旋管柱内携砂流体中砂粒运移的动力学方程，得出了等径直管和双螺旋管柱内砂粒的运动速度计算模型。研究得出，双螺旋水力喷射压裂管柱及喷射器能起到螺旋旋流作用，均衡双簇水力喷射压裂效果和降低上、下游水力喷射器冲蚀的非均匀性；等径直管内砂粒的运动规律符合恒定加速度运动方程，双螺旋管内砂粒的运动规律符合变加速度运动方程。研究结果表明，采用双螺旋结构水力喷射压裂管柱及喷射器是可行的，在均衡多级水力喷射压裂效果和提高水平井筒内携砂流体携砂能力方面具有显著作用。 

Hydraulic Jet Fracturing Technology Based on Archimedes Spiral Theory

The multi-stage double-cluster hydraulic jet often encounters problems such as that of relative ineffectiveness,uneven erosion between the upstream and downstream by the injector,and sanding problems caused by the easy settlement of sands.To overcome these challenges,the theory of Archimedes double helix was utilized and integrated to a mathematical model of hydro jet fracturing,which provides the basis in the design of the double-helix hydraulic fracturing tubing string and injector.Then visualizations of the sand-carrying evaluation experiments were performed to evaluate the double-helix characteristics.In addition,kinetic equations of sand migration in sand-carrying fluid through straight pipes and double-helix pipes with the same diameter under hydraulic fracturing conditions were obtained based on Newton’s second law,then transformed into the calculation models of the kinetic velocity of sands.As indicated in the research,the double-helix hydraulic fracturing pipe strings and injector can generate rotational flow,which help to balance double-helix hydraulic fracturing effects,and reduce erosion unevenness between the upstream and the downstream.The movement of sands can be described in a model by the accelerated movement equation with a constant accelerated velocity and varied accelerated velocity inside straight pipes and double-helix pipes,respectively.The research demonstrated that the double-helix hydraulic fracturing pipe strings and injector can function well,which are feasible evidently in balancing the multi-stage hydraulic fracturing effects and improving sand-carrying capacity of fluid along horizontal wellbores.