大位移井中利用钻柱旋转作用清除岩屑床的机理研究

A STUDY OF THE MECHANISM TO REMOVE CUTTINGS BED IN EXTENDED REACH WELL BY UTILIZING ROTATIONAL ACTION

井眼净化 ,是大位移钻井的关键技术之一 ;大位移井中 ,岩屑床是制约井眼净化的关键性因素。除钻井水力、钻井液流变参数外 ,钻柱的旋转作用是清除岩屑床的一个重要因素。通过对钻柱旋转作用下的环空流场的研究和分析 ,揭示了钻柱旋转对清除岩屑床的力学机理 ,即旋转作用使压力分布呈现波动形式 ,产生了有利于清除岩屑的循环力和陀螺力。波动的压力使岩屑床趋于非稳定 ,而循环力和陀螺力则对岩屑床产生搅动和支承作用 ,便于环空上返流速对岩屑的携带。并以国内大港油田大位移井红 9— 1为例 ,说明了钻柱旋转在大位移井中对清除岩屑床的重要作用。

Hole cleaning is one of the key techniques in extended reach well drilling.For extended reach well,the cuttings bed is the key factor restricting hole cleaning.Besides the hydraulic action and rheological parameter of mud,the rotational action of drilling string is an important factor for removing the cuttings bed.Through researching and analyzing the annulus flow field under the rotational action of drilling string,the mechanical mechanism of removing cuttings bed by rotation of drilling string is revealed,namely the rotational action makes the pressure distribution fluctuated,causing a circulating force and gyroscopic force favourable to cuttings removal.The fluctuant pressure makes the cuttings bed unsteady but the circulating and gyroscopic force serves the function as stirring and supporting the cuttings bed,being convenient to make the cuttings to be carried by the annular return velocity.Taking the well Hong 9 1 in Dagang Oil Field for example,the important role of the rotation of drilling string in removing cuttings bed in extended reach well is expounded.