钻井液压力波激发的钻柱应力波传播特性研究

It has always been a hot and difficult topic to improve the transmission rate and distance of the MWD information transmission technology . Aiming at the short distance of high data rate information transmission caused by the serious attenuation of the high frequency pressure wave propagating in the drilling fluid and the low energy acoustic transducer in the acoustic telemetry system , this project proposes the idea that using the high energy drillstring stress wave excited by the pressure wave generator as the transducer of the acoustic telemetry system, and studies the serious attenuation problem caused by the contact between the drillstring and the well. The coupling model of the pressure wave generator and the drillstring is established, then the suppressing method of the noise generated by the multipath coupling and the influences of different structure parameters on the energy distribution of the pressure wave and the stress wave are analyzed. The non-linear contact model of the stress wave propagation at the frictional contact interface between the drillstring and the well is established, then the reflection and transmission at the interface are discussed. The stress wave propagation model based on the contact between the drillstring and the well is established, then the influences of the drilling parameters, the formation characteristics and the friction coefficient on the stress wave propagation properties are analyzed. Finally, the theoretical research conclusions will be evaluated by the stress wave excitation and propagation experiments. The research results of this project will provide the theoretical basis and experimental support for the MWD information transmission technology with the high data rate and long distance.

提高信息传输速率与传输距离一直以来都是随钻测量信息传输技术研究的热点与难点。本项目针对高频压力波信号在钻井液信道内衰减严重和现有声波信息遥传技术中信源能量低下导致的高速率信息传输距离短的问题，提出应用钻井液压力波信号发生器激发高能量钻柱应力波进行声波信息遥传的思路，并对钻柱与井壁接触导致钻柱应力波衰减严重的问题进行研究。建立压力波信号发生器与钻柱的耦合模型，分析多径耦合引起的杂波及抑制措施、不同结构参数对压力波与应力波能量分配的影响；建立钻柱应力波在钻柱与井壁摩擦接触界面处的非线性接触传播模型，分析接触界面上反射、透射的影响因素及规律；建立基于钻柱-井壁接触的钻柱应力波的传播模型，分析钻井参数、地层特性、摩擦系数等对钻柱应力波传播特性的影响；最后进行钻柱应力波激发与传播特性实验研究，验证理论分析结果。项目研究成果将为高速率、长距离随钻测量信息传输技术提供理论依据与实验支持。

提高信息传输速率与传输距离一直以来都是随钻测量信息传输技术研究的热点与难点。本项目针对高频压力波信号在钻井液信道内衰减严重和现有声波信息遥传技术中信源能量低下导致的高速率信息传输距离短的问题，提出应用钻井液压力波信号发生器激发高能量钻柱应力波进行声波信息遥传的思路，并对钻柱与井壁接触导致钻柱应力波衰减严重的问题进行研究。完成了钻井液压力波信号发生器与钻柱的相互作用的有限元模型的建立与分析，弄清了压力波信号发生器在钻柱内产生应力波的机理。建立了钻柱与井壁接触的有限元模型，分析了法向接触力、接触宽度、地层特性、摩擦系数等因素对接触界面上反射、透射的影响规律，研究了摩擦接触对透射系数和反射系数的影响。建立了井筒内钻柱的有限元模型，考虑钻柱与井壁的接触，分析了全井段钻柱与井壁的法向接触力的分布规律。针对压力波信号发生器的高温工作环境的特点，为压力波信号发生器的控制电路和电机设计了强制冷却保温舱；针对压力波信号发生器的电力供应问题，设计了从钻柱振动中吸取能量的振动发电机；建立了控制电机的硬件控制系统，并编制了控制程序；建立了实验管路系统，进行了验证性实验。