大位移井钻进过程中动态岩屑运移与钻柱受力耦合机理研究

In extended reach drilling (ERD), it is common to have cuttings bed packed in the deviated parts of the wellbore. Cuttings transport efficiency and the forces acting on the drill string can affect each other significantly. However, traditional studies on cutting transport and tubular mechanics were isolated from each other, little work has been done on the mechanisms of coupling these two aspects together. This proposed research project will tackle the problems that are commonly encountered during drilling of ERD wells, such as poor hole cleaning, large friction resistance on drill string, insufficient weight on bit, stuck pipe, difficulties in sliding drilling, by coupling dynamic cuttings transport and tubular mechanics. The research scope includes experimental tests of dynamic cuttings transport and its effect on the forces acting on the drill string, development of a coupled transient cuttings transport and torque & drag (T&D) model to simulate the effect of cuttings on torque, drag, and drill string movement. Results of this work will provide important theoretical foundation and practical guidance for improving drilling design, predicting and avoiding problems related to poor hole cleaning and stuck pipe during drilling extended reach wells.

大位移井钻进时普遍存在岩屑床，岩屑运移效果与钻柱受力状态相互影响和制约。传统研究将岩屑运移分析和管柱受力分析相互分隔，独立研究。本项目针对大位移井钻进过程中井眼清洗难、钻柱摩阻大、钻头加压困难、卡钻事故率高、滑动钻进困难等工程难题，围绕动态岩屑运移与钻柱受力相互作用这一关键点，通过开展动态岩屑运移与钻柱受力耦合的室内模拟实验和理论分析研究，探索在大位移井中不同井斜区间段钻进时岩屑分布和钻柱受力的变化规律；分析井眼中沉积的岩屑对钻柱受力的影响；建立动态岩屑运移与钻柱力学耦合的系统计算模型；分析大位移井钻进过程中，岩屑床分布与钻柱扭矩、轴向力、钻柱运动能力之间的关系，为在大位移井工程实际应用中优化钻井设计，制定钻进方案，预测岩屑堆积和减小钻柱摩阻提供理论支撑和科学依据。

岩屑运移和钻柱受力问题是大位移井钻井的关键技术之一，了解大位移井钻进过程中岩屑分布剖面及钻具受力状况，对于大位移井钻井作业高效、安全的进行有重要意义。项目围绕动态岩屑运移与钻柱受力相互作用这一关键点，通过室内试验和理论分析相结合的方法，开展动态岩屑运移和钻柱受力耦合规律的研究。项目取得的主要研究成果如下：（1）研制并开发了岩屑运移与钻柱受力耦合实验平台，设计了相关实验过程，为耦合规律研究、验证提供了科学途径；（2）建立了大位移井统一动态岩屑运移模型，为大位移井钻井过程中岩屑动态变化提供模型参考，也为井眼清洁状况判断提供了理论依据；（3）研究并建立了岩屑分布与钻柱力学耦合系统模型，实现了大位移井钻进过程中，岩屑对扭矩、钻柱轴向摩阻的定量分析，填补了研究空白。本项目的研究，为解决大位移井岩屑运移和钻柱受力难题提供了理论支撑和科学依据。