斜井和水平井钻井环空流核区及速梯区中岩屑的运移研究

长期以来，斜井和水平井的环空岩屑运移问题制约着斜井和水平井钻井，国内外学者在这方面做过大量的实验和理论研究，以液/固两相流为基础的理论模型在不断的发展。文章采用了新的研究方法，取岩屑颗粒单元为研究对象，通过分析偏心环空中流核区及速梯区岩屑颗粒的主要受力，来预测岩屑颗粒的运移趋势，通过数值计算，分析了井斜角、岩屑密度、钻井液返速对流核区中岩屑运移的影响、钻井液返速对速梯区中岩屑运移的影响及旋转钻柱能提高岩屑运移行程的机理，得出了一些对解决斜井和水平井钻井的环空岩屑运移问题有重要意义的结论。

RESEARCH ON CUTTINGS MIGRATION IN THE FLOW CORE ZONE AND VELOCITY GRADIENT ZONE OF ANNULAR SPACE IN DRILLING INCLINED HOLE AND HORIZONTAL HOLE

For a long time past, the problem with cuttings migration in annular space has restrained the development in drilling inclined hole and horizontal hole. A great number of tests and theoretic researches on this problem have been done by the domestic and foreign scholars and the theoretic model based on liquid/solid two-phase flow has been unceasingly expanded. By taking cuttings unit as the research target, the migration trend of the cuttings unit may be predicted on the basis of analyzing the forcing circumstances of the cuttings unit of the flow core zone and velocity gradient zone in eccentric annular space. According to numerical calculation and through analyzing the influence of the deviation angle, cuttings density and drilling fluid return velocity on cuttings migration in flow core zone, the effect of the drilling fluid return velocity on cuttings migration in velocity gradient zone and the mechanism of raising cuttings migration distance by rotary drilling string, some important conclusions of settling the problem with the cuttings migration in the annular space in drilling inclined hole and horizontal hole are achieved in the paper.