摘要
基于水击压力波的压裂诊断技术可用于快速判别裂缝位置,进而用于压裂工艺优选与施工参数优化。水击波波速是水击压力波诊断的关键参数,波速计算的读取方法对波速的准确性产生较大影响。为了精确计算水击波波速、减小波速变化引起的裂缝深度计算误差,搭建水击压力波试验系统,开展水平管路中压力波波速试验。使用4种方法计算压力波波速:描点读取压力突变点法、小波分解结合互相关函数法、描点读取水击周期法、基于频谱分析的水击周期法。以平均值、标准差及变异系数为指标,分析4种方法波速计算的数值结果与稳定性。在该试验中,针对10 kHz的采样频率,使用小波分解结合互相关函数法时优选出最优小波基函数为db4小波,最优分解层数为10层。使用双传感器计算的方法(描点读取压力突变点法与小波分解结合互相关函数法)得到的压力波波速高于单传感器计算得到的方法(描点读取水击周期法与基于频谱分析的水击周期法)。结果表明:双传感器法得到的波速范围为959.08 m/s至1111.11 m/s;单传感器法得到的波速范围为619.98 m/s至859.98 m/s。小波分解结合互相关函数方法在数据稳定性方面效果最好,可重复性最强;采用频谱分析的水击周期计算得到的标准差最大,可重复性最差。研究成果可供压裂停泵中水击波波速计算参考。
The surge pressure wave(water hammer pressure wave)-based fracturing diagnosis technique can quickly identify fracturing location and then can be used to optimize the fracturing technology and the relevant construction parameters.As water hammer wave velocity is the key parameter for the diagnosis of water hammer pressure wave,the reading method of wave velocity calculation has large influence on the correctness of the wave velocity.In order to accurately calculate water hammer wave velocity and reduce the calculating error of fracturing depth,an experimental system of surge pressure wave(water hammer pressure wave)is built up for carrying out the experiment on the pressure wave velocity inside horizontal pipeline.The pressure wave velocity is calculated with four methods,i.e.the method of tracing point reading of pressure mutation point,the method of wavelet decomposition combined with cross correlation function,the method of tracing point reading of water hammer period and the spectrum analysis-based water hammer period method.Taking mean value,standard deviation and variation coefficient as the indexes,the numerical results and stabilities of the wave calculations made by the four methods mentioned above are analyzed.In this experiment,the optimal wavelet basis function optimized with the method of wavelet decomposition combined with cross correlation function is db4 wavelet with the optimal number of decomposition levels of 10 for the sampling frequency of 10 kHz.The pressure wave velocity obtained by the method of dual sensor calculation(the method of tracing point reading of pressure mutation point and the method of wavelet decomposition combined with cross correlation function)is higher than that obtained from the single sensor calculation(the method of tracing point reading of water hammer period and the spectrum analysis-based water hammer period method).The results show that the wave velocity range obtained by the dual sensor method is 959.08 m/s~1111.11 m/s,while the wave velocity range obtained from the single sensor method is 619.98 m/s~859.98 m/s.The method of wavelet decomposition combined with cross correlation function has the best effect of data stability with the strongest repeatability,while the standard deviation obtained from the water hammer period calculation of frequency spectrum analysis is the largest with the worst repeatability.The study results can provide a reference for calculating the water hammer wave velocity during pump shutdown caused by fracturing.
作者
胡晓东
李卓龙
周福建
丘阳
李宇娇
罗英浩
HU Xiaodong;LI Zhuolong;ZHOU Fujian;QIU Yang;LI Yujiao;LUO Yinghao(Unconventional Petroleum Research Institute,China University of Petroleum(Beijing),Beijing102249,China)
出处
《水利水电技术（中英文）》
北大核心
2022年第5期106-118,共13页
Water Resources and Hydropower Engineering
基金
国家自然科学基金青年基金项目“基于水击压力波信号的多裂缝识别方法研究”(52004300)。
关键词
水击波波速
压力突变点
小波分解
水击周期
变异系数
水力特性
稳定性
水力压裂
water hammer wave velocity
pressure mutation point
wavelet decomposition
water hammer period
coefficient of variation
hydraulic characteristics
stability
hydraulic fracturing
作者简介
胡晓东(1990-),男,副研究员,硕士研究生导师,博士,研究方向水力压裂裂缝扩展/支撑剂运移机理、水力压裂诊断与评估研究。E-mail:huxiaodong@cup.edu.cn。
