Investigation of the factors affecting the self‐propelled force in a multi‐orifice nozzle using a novel simulation method

Abstract

AbstractA multi‐orifice nozzle is the primary actuator of radial jet drilling for the stimulation of unconventional and low‐permeability reservoirs. This research developed a 3D flow field simulation model to investigate the self‐propelled force of a multi‐orifice nozzle based on ANSYS‐CFX. To evaluate the self‐propelled ability of the nozzle, investigation was performed on the effects of the angle, number, the diameter of the forward and backward orifices of the multi‐orifice nozzle, and the diameter of the micro‐hole in the radial well on its self‐propelled ability by sensitivity analysis. The results revealed that the self‐propelled force slightly increased with the angle of forward orifice increasing, and decreased with the angle of backward orifice increasing; and that the self‐propelled force had a tendency to decrease significantly with the number of forward orifices increasing, and increased slightly with the number of backward orifices increasing. The self‐propelled forces for different combinations of forward and backward orifices were obtained by the simulation method, which agreed well with those obtained by the calculation method, with an average accuracy of 95.82%. It was observed that the self‐propelled force increased substantially as the value of K (d2/d1) increased, but tended to slow down when the flow rate was within a certain range. Besides, with the increase in the diameter of the micro‐hole, the self‐propelled force reduced, and increased substantially as the inlet flow rate increased, but tended to slow down as the inlet flow rate further increased. Thus, to ensure the self‐propelled ability of the jet nozzle, a set of optimal structural parameters can be used to generate the target self‐propelled ability. The research improves the working performance of multi‐orifice nozzles and provides theoretical guidance for hydraulic radial jet drilling process.