Numerical simulation on the flow field of self-propelled multi-orifices nozzle for ultra-short radius radial jet drilling

Abstract

Ultra-short radius radial jet drilling (USRRJD) is a beneficial method to develop the conventional and unconventional oil and gas resources. Nozzle is a self-propelled bit and key tool for USRJD, which could rapidly erode the targeted formation, and then form to regular hole to produce. Multi-orifice nozzle is a special self-propelled bit. This paper introduced flow field characteristics of multi-orifice nozzle jetting by numerical method. Combined with the mathematical and RNG k-e turbulent model, physical model is established. The simulated self-propelled force coincides well with the reported experimental data. The simulated results show that the flow field includes four areas, such as forward flow, cross flow, backward flow and low velocity. Forward orifices enlarge bottom hole impact zone which is beneficial to enlarge hole diameter, the maximum axial velocity of forward orifices is deviated due to absorption of central orifice. Backward orifices can further enlarge hole diameter and generate self-propelled force. Wall adsorption in backward orifices results in low velocity of backward jetting, which would decrease the propelled force. This study provided the reference for optimising multi-orifice nozzle and operation parameters. [Received: September 18, 2015; Accepted: July 17, 2016]