Abstract:

The coiled tubing used in the micro-hole drilling has the shortcomings of slender and highly flexible structure.The drilling weight on bit acted by the popular collar is difficult to meet the requirement of the micro-hole drilling.A micro-hole hydraulic thruster was designed to employ in borehole with a diameter of 88.9 mm.A computation model for drilling weight on bit while the hydraulic thruster connected above the mud motor was proposed,in consideration of the effects of mud motor,friction between side wall and drilling string beneath the thruster,friction between the moving components of thruster and the inner wall of its housing on the bottom of drilling weight.Solving the model could derive the relation curves of flow rate and nozzle diameter with the weight on bit.The research results can provide the reference for application of hydraulic thruster in micro-hole drilling.

Key words: micro-hole, hydraulic thruster, structure design, drilling collar, friction, weight on bit, computation model

摘要：

微小井眼钻进过程中,连续管的直径小、刚度低,采用传统的钻铤施加钻压不能满足钻井需要,为此设计了一种用于88.9mm井眼的微小井眼水力加压器。综合考虑井下马达、水力加压器以下钻柱与井壁的摩擦力、水力加压器运动部件与缸体内壁的摩擦力等因素对井底钻压的影响,建立了水力加压器串联在井下马达上方时井底钻压计算模型,通过对模型的求解可以得到钻井液流量、喷嘴直径与钻压关系曲线,为水力加压器在微小井眼钻进中的应用提供了理论依据。

关键词: 微小井眼, 水力加压器, 结构设计, 钻柱, 摩擦力, 钻压, 计算模型