空气携岩能力数值模拟分析

EFFECT OF INCLINATION,ECCENTRICITY,ROD ROTATIONAL SPEED ON SOLIDS-CARRYING CAPABILITY DURING AIR DRILLING

井斜、环空偏心率、钻杆转速等对井筒压降与空气携岩能力有着显著影响,但因其变化范围大,变化组次多,将影响程度定量化还比较困难,而这些恰是指导安全钻进的主要依据。文章基于计算流体动力学方法建立了空气钻井环空内气固两相流动的数学模型,通过数值模拟得出了不同井斜角、不同环空偏心距、不同钻杆转速条件下环空内流场与气固相体积浓度分布,分析了井斜、偏心、钻杆转速对空气携岩能力的影响,为空气钻井安全钻进与井眼净化评价提供依据。

Borehole inclination,annulus eccentricity and drill pipe rotational speed strongly affect pressure loss and air solids-carrying capability in the annulus.Due to the complex factors,accurately calculating the pressure loss and the solids-carrying capability are difficult,while these factors are the important basis for safe drilling.Mathematical model of gas-solids flow properties was set up based on the computation fluid dynamics theory.The distributions of flow properties and volumetric cuttings concentration with variable inclination,eccentricity and rotational speed were got by the simulation.Then impacts of the solids-carrying capability were analyzed with variable factors.Some references could be provided to guide safe drilling and appraise borehole cleaning in practice.