同步提取三参数小波变换及其在储层含气性检测中的应用

Synchroextracting three-parameter wavelet transform and its application in hydrocarbon detection of reservoir

随着我国石油勘探程度的不断加深,非常规油气藏逐步成为了油气勘探的重点.由于致密砂岩具有低孔、低渗、非均质性强等特性,因此迫切需要高精度时频分析后处理方法对该类气藏进行有效表征.本文提出了一种同步提取三参数小波变换(Synchroextracting Three-Parameter Wavelet Transform, SETPWT)新方法,该方法具有小波变换多尺度多分辨率的特性,通过改变三个参数来调节小波基的主频、带宽及相位,灵活匹配多种类型的合成信号以及地震子波;与传统时频分析方法相比,同步提取三参数小波变换在三参数小波变换结果的基础上引入同步提取算子(Synchronous Extraction Operator, SEO),通过SEO提取与信号理想时频谱高度相关的时频信息,去除多余能量,从而实现非平稳信号的高精度时频表征.合成信号算例表明,同步提取三参数小波变换的分辨率不但明显高于常用时频变换,同时具有优于同步提取变换(Synchroextracting Transform, SET)的抗噪性能;将同步提取三参数小波变换应用到地震资料含气性检测中,进一步验证了该时频算法在致密砂岩含气性检测中的潜力.

With the deepening of petroleum exploration in China, unconventional hydrocarbon reservoirs have gradually become the focus of hydrocarbon exploration. Because tight sandstone has the characteristics of low porosity, low permeability and strong heterogeneities, it is urgent to use high-precision time-frequency analysis postprocessing methods to effectively characterize this kind of hydrocarbon reservoir. The Synchroextracting Three-Parameter Wavelet Transform(SETPWT) proposed in this paper has the characteristics of multi-scale and multi-resolution like Wavelet Transform. The main frequency, bandwidth and phase of the wavelet base can be changed by adjusting three parameters, which can match various synthetic signals and seismic wavelets flexibly. Compared with the traditional time-frequency analysis methods, SETPWT introduces the Synchronous Extraction Operator(SEO) based on the results of Three Parameters Wavelet Transform. Furthermore, through SEO, SETPWT extracts the time-frequency information highly related to the ideal time-frequency representation of the signal, and removes the redundant energy, thereby achieving a highly energy-concentrated time-frequency representation result for nonstationary signals. The analysis results of synthetic signals show that the resolution of the SETPWT is not only higher than that of the common time-frequency transform, but also has better anti-noise performance than that of the Synchroextracting Transform(SET). The application of the field seismic data further verifies the potential of the SETPWT in the hydrocarbon detection of tight sandstone.