【作者】 朱军；

【导师】 沈跃；

【作者基本信息】 中国石油大学 ， 物理学， 2010， 硕士

【摘要】 随钻测量技术(MWD)是一种在钻井操作的同时对井下参数进行实时测量与传输的现代钻井辅助技术,依靠钻井液信道进行井下信息的遥测是目前井下随钻测量数据传输的有效方法,钻井液压力正交相移键控(QPSK)调制方式因其具有信息传输速率高和抗干扰能力强等特点,已成为钻井液信息遥测技术的发展方向。本文从旋转阀式钻井液连续压力波信号发生器的工作机理入手,说明了钻井液压力QPSK信号的调制过程。钻井液压力QPSK信号是基带信号根据调制规则对旋转阀转速调制产生的调相信号。基于基带信号及钻井液压力QPSK信号的信号特征分析,构建了钻井液压力QPSK信号的数学模型,并对QPSK信号的时域特性和频域特性进行了分析。研究表明,由于基带信号控制对象和控制方式不同,钻井液压力QPSK信号与常规电子通信系统的QPSK电信号在频谱分布上有一定区别,但其共同点是都存在明显的主频带,便于基带数据的频带传输,且频带跟随载波频率同步移动,有利于通过改变载频的方式避开干扰信号的影响。相对于数据的二进制差分相移键控(BPSK)调制,钻井液压力QPSK调制在相同的带宽下,信息传输速率和频带利用率均提高了一倍,只是调制后常规带宽内信号能量相对小于BPSK信号。通过对钻井液压力QPSK信号的数学分析,从理论上证明了QPSK调制技术用于井下测量数据高速率传输的可行性。应用流体力学理论和理想气体状态方程,分析了钻井液温度和压力沿定向井钻柱的分布规律;根据声学理论研究了定向井造斜段钻柱对钻井液压力波信号传输的影响,研究表明,由于造斜段的曲率半径远大于钻柱内径,压力波经过造斜段时的入射角接近于直角,在造斜段的钻柱内壁产生声波全反射,不会产生额外的能量损失,造斜段钻柱对信号传输的影响与垂直段相同;根据温度和压力对钻井液含气率的影响关系,建立了定向井中压力信号传递函数的数学模型,采用数值分析方法研究了钻井液压力QPSK信号自井底上传过程中,钻柱内径、载波频率、钻井液黏度及体积含气率等参数变化对信号传输的影响。更多还原

【Abstract】 Measurement while drilling(MWD) is a kind of modern drilling assisted technique, through which down hole parameters can be measured and transferred simultaneously while drilling. On the basis of down hole information telemetry through drilling fluid channel, MWD is an effective method to transfer measured data while drilling. Enjoying the advantages of high information transferring rate and strong anti-interference, drilling fluid pressure quadrature phase shift keying (QPSK) modulation is the development trend of drilling fluid information remote measurement technique.According to working mechanism of rotary valve drilling fluid continuous wave signal generator the process of QPSK modulation were built. Drilling fluid pressure QPSK signals is PM signals generated by modulation on rotary valve speed by baseband signals. Based on signature analysis of baseband signals and Drilling fluid pressure QPSK signals, mathematical model of drilling fluid pressure QPSK signal was built, and, time domain and frequency characteristics of QPSK signal were analyzed. Research indicates that, since control object and control manner of baseband signal are different, drilling fluid pressure QPSK signals and the QPSK electrical signal of the conventional electronic communication system have some differences. While both of them have obvious frequency band, which can facilitates frequency band transmission of baseband data, and, frequency band moves with carrier frequency simultaneously, which can avoid the impact of interference signal on frequency band transmission data by changing carrier frequency. Under the same bandwidth, compared with binary data differential phase shift keying(BPSK), drilling fluid pressure QPSK modulation can double information transfer rate and bandwidth utilization efficiency, and modulated signal energy in regular band is just slightly smaller than that of BPSK signal. Through mathematical analysis of drilling fluid pressure QPSK signal, feasibility of QPSK modulation technique using in transferring down hole data at high speed was proved theoretically.Through hydrodynamic theory and equation of state of ideal gas, distribution of drilling fluid temperature and pressure along the directional well string was studied. According to acoustical theory, effect of drilling string in buildup section of directional well to signal transmission of drilling fluid pressure wave was studied. Research indicates that, radius of curvature is much bigger than string internal diameter, thus incident angle of pressure wave in buildup section is close to right angle, then total acoustic reflection is generated in inner wall of string during buildup section, and additional energy loss cannot be generated, so effect of buildup section to signal transmission is same to straight section. According to effect of temperature and pressure to drilling fluid gas-bearing ratio, mathematical model of pressure signal transfer function in directional well was obtained. Through numerical analysis method, effect of string internal diameter, carrier frequency, drilling fluid viscosity and gas fraction to drilling fluid pressure QPSK signal transmit from down hole to surface were studied.更多还原