空气钻井井眼净化与冲蚀效应模拟分析

Numerical simulation of hole cleaning and erosion effect for air drilling

空气钻井环空气固两相流场分布、工艺参数设计方面的研究较少。笔者基于流体动力学与空气动力学理论,采用有限体积法对气固两相流动控制方程进行了离散求解,模拟分析了不同注入参数条件下环空内的压强和流速分布,着重分析了"关键点"处的流场分布,并结合井眼净化和冲蚀效应评价方法,选取了合适的注入参数。模拟所得压强、流速分布均与实际情况吻合较好,并为实际工程参数设计(比如注入压力及井口回压确定)提供了依据,研究成果已用于指导川庆钻探公司空气钻井施工。

Previous papers rarely focused on the distribution of gas-solid two-phase flow in annulus and the qualifications of technical parameters in air drilling.Based on the computation fluid dynamics and aerodynamics theory,finite volume method was employed for the discrete solving of the gas-solid two-phase flow governing equation in this paper.Then the distribution of pressure and flow velocity in annulus with variable injecting parameters were analyzed,especially the flow field distribution at key points.Combined with the hole cleaning and erosion effect evaluation methodology,suitable injecting parameters were obtained.The pressure and flow velocity distribution obtained by the simulation was in good agreement with the actual situation.Some references are provided to design the injecting pressure and wellhead back pressure in practice.Research results had been used to guide the air drilling in Chuan-Qing Drilling Company.