摘要
VSP(Vertical Seismic Profiling)资料采集过程中,由于水泥固井不牢或多层套管之间水泥环空等原因,容易产生套管耦合噪声。该类噪声具有能量强、空间影响范围广、衰减缓慢等特点,且与有效信号在时间域、频率域等多域重叠,严重影响了VSP资料的信噪比。首先介绍了形态成分分析(Morphological Component Analysis,MCA)的基本理论,然后对比分析了有效信号和套管耦合噪声在时域、频域及时频域分布特征差异,接着将VSP资料建模为有效信号、套管耦合噪声及随机噪声之和,最终提出基于特征波形态成分分析的VSP资料套管耦合噪声压制方法。该方法选用Q可调小波变换(有效信号的稀疏表示字典)和余弦变换(套管耦合噪声的稀疏字典)构建了相应的超完备字典,然后采用分块坐标松弛法实现了VSP资料中套管耦合噪声的压制。实际VSP资料处理结果表明,该方法对套管耦合噪声能量及频域分布区域的变化具有良好的自适应性,在明显压制该类噪声的同时对有效信号具有良好的保真性。
During the acquisition of vertical seismic profile(VSP)data,coupling noise between casing strings frequently emerges due to poor well cementing or the presence of cement annulus between multiple casing layers.This type of noise features high energy,a wide spatial influence range,and slow attenuation.Furthermore,it overlaps effective signals in multiple domains,such as the time and frequency domains.Therefore,casing coupling noise severely affects the signal-to-noise ratio of VSP data.This study first introduces the basic theory of Morphological Component Analysis(MCA).Then,it conducts a comparative analysis of the distribution of effective signals and casing coupling noise in the time,frequency,and time-frequency domains.Subsequently,this study processes the VSP data as a combination of effective signals,casing coupling noise,and random noise through modeling.Finally,it proposes a MCA-based method for suppressing casing coupling noise mixed in the VSP data.In this method,corresponding overcomplete dictionaries are constructed utilizing the tunable Q-factor wavelet transform(a sparse representation dictionary for effective signals)and the cosine transform(a sparse representation dictionary for the casing coupling noise).Then,the block coordinate relaxation method is employed to suppress the casing coupling noise in the VSP data.As indicated by the processing results of actual VSP data,the method proposed in this study enjoys high adaptability to the changes in the energy and frequency-domain distribution zones of casing coupling noise.Furthermore,it exhibits high fidelity to effective signals while significantly suppressing such noise.
作者
潘龙
毛海波
蒋立
胡可扬
党志敏
陈文超
PAN Long;MAO Haibo;JIANG Li;HU Keyang;DANG Zhimin;CHEN Wenchao(Institute of Geophysics,Research Institute of Exploration and Development,Xinjiang Oil Field Branch Company,China National Petroleum Corp.,Urumchi 830013,China;School of Information and Communication Engineering,Xi’an Jiaotong University,Xi’an 710049,China)
出处
《煤田地质与勘探》
EI
CAS
CSCD
北大核心
2023年第7期184-190,共7页
Coal Geology & Exploration
基金
国家重点研发计划项目(2021YFA0716904)
国家自然科学基金项目(41974131)。
关键词
垂直地震剖面法(VSP)
信噪分离
波形形态分析
套管耦合噪声
Vertical Seismic Profiling(VSP)
signal-noise separation
waveform morphological analysis
casing coupling noise
