激励压力波漏层定位理论研究

Lost circulation is the most common technical problem during drilling engineering, and plugging technology is critical after loss circulation occurred, but the premise of plugging is to locate the lost circulation position accurately. At present, locating the lost circulation position mostly has two methods: the hydraulic calculation method and the directly measuring by tripping instrument in well hole. The former method limited by the selected hydraulics model has large deviation, the latter method using the expensive instrument has the complex work progress. In recent years, more researches adopt the pressure wave to detecting pipeline leak home and abroad. The active incentive pressure wave can be applied to locate the position of the tiny leakage or leaking steady state.Therefore, application of the active incentive pressure wave to the lost circulation detection can give full play to the advantages of the pressure wave detection technology, and overcome the existing shortcomings of the detecting lost circulation methods. The project aims at forming a complete pressure wave locating lost circulation position theoretical model and calculation method, based on the theoretical and experimental analysis method. The study about the pressure wave propagation in borehole is performed to locate the lost circulation position based on amplitude frequency characteristics analysis and water hammer transfer theory. With the pressure wave signal detection and digital signal processing technology, the correlation is analyzed between the lost circulation position, the leakage rate and the pressure wave amplitude frequency.This project is characterized mainly by (1) Establishing a theory model of pressure wave propagation under the lost circulation conditions; (2) Forming a signal processing method of accurate extraction lost circulation characteristics.

井漏是钻井工程中最常见的技术难题之一，井漏发生后及时进行堵漏非常关键，但是堵漏的前提是必须准确地找到漏层。目前，漏层定位方法主要有水动力学计算法和下入井下仪器测定法，前者受水力学模型等限制误差较大，后者所用仪器昂贵，施工复杂。近年来国内外对压力波检测管道泄漏研究较多，采用主动激励压力波还可以在微小泄漏或泄漏达到稳态时使用。因此，将主动激励压力波检测方式应用到井漏检测中，可以充分发挥压力波检测技术的优势，克服现有漏层定位方法的不足。项目拟采用理论研究与实验分析相结合的方式，从漏层定位问题出发，利用幅频特性分析和水击传递理论，研究压力波在井筒内的传播特性。借助压力波信号检测和数字信号处理技术，分析漏层位置和漏失量与压力波的幅频关系，形成完整的压力波定位漏层的理论模型和计算方法。本项目特色主要为（1）建立一套井漏条件下压力波传播理论模型；（2）建立精确提取井漏特征的信号处理方法。

井漏在钻井过程中会造成重大经济损失。井漏发生后堵漏是关键，快速确定漏层位置并堵漏能大大降低损失。检测方法分为水动力学计算法和检测仪器下井检测法，前者准确性差，后者施工强度大。本项目从压力波检测角度利用现地面节流管汇系统进行压力波激励，压力波在漏层处发生反射和折射，其幅频特性将发生变化，对地面检测到的压力波进行漏层特征提取，定位漏层。采用理论研究与室内实验相结合，建立了流道特征对激励压力波传播速度影响模型；分析了地面实施压力波激励条件下的井筒内漏层位置对压力波的反射和折射规律。设计了模拟地面激励压力波进行井筒漏层位置定位检测实验装置。分析了井漏信号特征提取方法，即激励信号滤波后，在频域范围内与漏失位置的对应关系。该方法不需下入井下仪器，提高漏层定位效率、降低施工成本、减少施工的复杂性和发生井下复杂情况的几率。