水平井段泡沫流体瞬态携屑数值模拟研究

Research on Numerical Simulation of Transient Cuttings Transport with Foam Fluid in Horizontal Section

考虑层间质量传递和地层流体的侵入,建立了描述水平井段泡沫瞬态携岩机理的一维双层流动模型,基于修正的SIMPLE算法对模型进行数值求解,岩屑床厚度预测采用试算法,对泡沫携岩影响因素进行了敏感性分析。结果表明:岩屑床随钻时从钻头沿井筒延伸,一定时间后达到动态平衡;无量纲岩屑床厚度随着泡沫特征值和泡沫流量的增大而减小,随着钻杆偏心度、岩屑粒径和机械钻速的增大而增大,地层气和水的侵入有助于提高泡沫携岩效率。该模型为水平井泡沫钻井的水力参数设计和井眼净化技术提供了理论依据。

Considering the interlayer mass transfer and fluid influx from the reservoir, a one-dimensional two-layer hydraulic model was established to describe the transient cuttings transport mechanism with foam fluid in horizontal section. The model was numerically computed based on the modified SIMPLE algorithm, and the cuttings bed height was predicted by the trial-and-error method. Sensitivity analysis was conducted on the affecting factors on the cuttings transport performance. The experimental results show that cuttings deposition moves along the horizontal wellbore from the drilling bit, and finally achieves a steady state of dynamic balance. Dimensionless cuttings bed height decreases with the increase of foam quality and foam flow rate, but increases with the increase of drill-pipe eccentricity, cuttings size and drilling rate. The influx of water and gas from the reservoir is helpful to improve the cuttings transport efficiency with foam. The proposed model offers theoretical guidelines for hydraulic parameter design and hole cleaning control in foamed horizontal drilling.