基于小波变换的浊积岩微相测井定量识别

Quantitative Identification of Turbidite Microfacies by Well-Logs Based on Wavelet Transform

摘要: 相较于河流–三角洲沉积体系，浊积岩整体呈现出滑塌沉积的块状搬运特征，测井相差异性较小，识别相对困难。在史深100沙三中亚段利用一阶中心距放大各测井相的差异性，并用低频小波系数对其进行重构。从水动力的强弱与稳定性等角度赋予小波系数对应的沉积学意义，结合高频与低频小波曲线的特征建立各微相对应的识别模板。通过计算未知微相的前10个低频小波系数与模板中小波系数的欧氏距离后优选最小者，即可判定浊积岩微相类型。判别后与取心井的微相对比发现正判率高达89%，不但提高了浊积岩沉积微相识别的精度，而且将测井相对沉积微相进行综合分析这一复杂问题简化为对少数几个低频小波系数进行计算。将识别结果与注采动态耦合指导井间砂体对比，有效地解决了浊积岩油藏同体不连通的问题，扩大了注水的波及范围。

Abstract: Compared to the fluvial-delta sedimentary system, the turbidite is presented in mass transport complexes. The logging facies differences are less variance among sedimentary microfacies of turbidite for the reason of slump deposition. These are the main factors that contributed to the difficulty in identifying. The logging facies differences were enlarged by computing first-order center distance. Then it was constructed by low-frequency wavelet coefficients. The sedimentary significances of wavelet coefficients were analyzed from the aspects of hydrodynamic strength and stability. The identified plates of all sedimentary microfacies were established by combining the characteristics of high-frequency wavelet curve and low-frequency wavelet curve. The shortest distance was optimized by calculating the Euclidean distance between the first 10 low-frequency wavelet coefficients of the unknown microfacies and the wavelet coefficients in the template. The unknown microfacies were identified as the optimized. The identify accuracy can reach up to 89% compared to the results with the microfacies of coring well. The identification accuracy was improved compared to traditional logging facies analysis. The complex study of comprehensive analysis of sedimentary microfacies by logging curves was turned into the calculation of a few low-frequency wavelet coefficients. The results were used to dissect inter-well sand body connectivity by coupling identification results with injection-production dynamics. The problem of disconnection in the same single sand body was solved effectively in this way. As a result, the swept range of water injection was expanded.