射孔完井水平井筒变质量流压降规律实验

Experiments on variable mass flow in perforated completion horizontal wells

目前各国学者主要针对注入比对射孔完井水平井筒变质量流压降的影响规律进行研究，而关于射孔相位、射孔直径、射孔密度对水平井筒变质量流壁面摩擦压降、混合压降、总压降影响规律的研究并不系统。因此笔者开展了射孔完井水平井变质量流压降规律实验研究。实验设计了三种射孔相位（45度螺旋射孔、90度螺旋射孔、180度螺旋射孔）、三种射孔直径（10、20、30mm）和三种射孔密度（8、16、24孔／m）、主流雷诺数为1000～20000、壁面注入比（单位井筒长度壁面入流量与主流流量的比值）为0．01％～10％。通过实验，研究了射孔相位、射孔直径、射孔密度对壁面摩擦压降、混合压降、总压降的影响规律，同时分析了壁面注入比对混合压降和加速度压降的影响规律。研究结果表明：随着射孔密度和射孔直径增大，壁面摩擦压降和总压降增大，混合压降减小；随着射孔相位增大，混合压降、壁面摩擦压降和总压降均增大；随着壁面注入比的增加，混合压降和加速度压降均增加。同时发现壁面注入比存在一个临界值，当壁面注入比小于此临界值时，混合压降为负值，加速度压降基本为零，总压降小于壁面摩擦压降；当壁面注入比大于此临界值时，混合压降开始为正值，加速度压降随着壁面注入比的增加而显著增加。

A considerable number of experimental work on the influence of flux ratio on variable mass flow in perforated completed horizontal wells has been published by many scholars, but the effects of perforation phasing, perforation diameter and perforation density on frictional, mixing and total pressure drop have not been studied systematically. In this paper,an experiment system is developed to investigate the influence of the perforation phasing,diameter and density. Three values of screw perforating phasing （45°,90°, 180°）, three kinds of perforation density （8 meter-1, 16 meter-1, 24 meter-1） and three sizes of perforation diameter （10 mm,20 mm,30 mm） are considered in the experiment of this paper. In the experiment,the Re （Reynolds number） of axial flow in pipe ranges from 1 000 to 20 000,the flux ratio （the ratio of the radial volume inflow at unit wellbore length to the axial volume flow in production pipe） ranges from 0.01% to 10~. The results indicate that：the frictional and total pressure drop increases while mixture pressure drop reduces with the increase of the perforation density and perforation diameter; the ＂mixing＂, frictional and total pressure drop all increases with the increase of the perforation phasing; the proportion of frictional pressure drop to total pressure drop reduces while the proportion of ＂mixing＂ and acceleration pressure drop increases with the flux ratio;the ＂mixing＂ and acceleration pressure drop increases with the flux ratio, but there exists a critical value of flux ratio. When the actual flux ratio less than the critical value, the ＂mixing＂ pressure drop is negative,the acceleration pressure drop is almost 0 that induces the total pressure drop less than the frictional term. When the actual flux ratio is bigger than the critical value, the ＂mixing＂ pressure drop increases to positive, and the acceleration pressure drop increases with the flux ratio obviously.