基于拉东变换的多尺度断裂识别方法及其应用

针对中深层低信噪比区断裂识别难的问题, 研究形成一套基于拉东变换多尺度断裂识别技术组合, 即对叠后地震数据进行压噪处理以提高初始地震资料信噪比, 压制随机干扰和高频噪声, 去掉岩性扰动等造成的弱边界信息; 通过分频处理检测不同频带地震数据对不同序级断裂的响应, 然后利用敏感性分析优选不同尺度断裂的敏感地震属性; 最后利用拉东变换技术进行边缘检测增强, 提高断层边缘效应。其核心思路是将基于图像重建理论的拉东变换引入到断裂三维解释中, 以区别常规边缘检测梯度算法, 拉东变换是一种积分运算, 具有线性增强、抗噪性强的特点。将该方法应用于珠江口盆地珠一坳陷浅水区断裂解释, 对不同序级断裂研究认为: ①相比于常规蚂蚁体切片, 显著提高了裂缝预测的精度和分辨率, 指示了陆丰13洼LF_A潜山构造主要发育北北西和北东向两组裂缝, 指导了花岗岩优质储层分布预测与评价; ②精细落实了阳江东凹EP_B构造断裂发育条件, 认为是受走滑作用控制的左阶雁列构造; ③陆丰C洼存在一条大型北东东向中央走滑断裂带, 与北西向调节断裂共同控制中央鼻状带圈闭形成, 新模式下发现了一批构造圈闭, 提高了洼陷勘探潜力。

Considering the difficulty in identifying faults in medium-deep strata with low signal-to-noise ratio (SNR), a multi-scale fault identification method based on Radon transform is developed. Specifically, the poststack seismic data are processed by noise suppression to improve the SNR of raw data. The noise suppression mainly deals with random interference and high-frequency noise, and removes weak boundary information caused by rock disturbance. The seismic responses at different frequency bands to different orders of faults are monitored through frequency division processing, and then sensitivity analysis is conducted to optimize the sensitive seismic attributes of faults of different scales. Finally, the Radon transform is used for edge detection enhancement to improve the fault edge effect. The method is essentially to introduce the Radon transform based on image reconstruction theory into the three-dimensional interpretation of faults, which is different from conventional edge detection algorithms. It is an integral operation with the characteristics of linear enhancement and high noise resistance. This method was applied for the first time in the shallow water area of the Zhu-I Sag, the Pearl River Mouth Basin. The results demonstrate that the proposed method significantly improves the accuracy and resolution of fracture prediction compared to conventional ant body slicing. It reveals that the LF_A buried-hill structure of the Lufeng 13 sag mainly develops two groups of fractures (NNW and NE), guiding the identification of high-quality granite reservoir distribution. The method helps confirm the fault development in the EP_ B structure of Yangjiang East sag, which is believed to be a left echelon structure controlled by strike slip. There is a large NEE-trending central strike slip fault zone in the Lufeng C sag, which, together with the NW-trending regulating fault, controls the formation of central nose shaped belt traps. Under the new model, a number of structural traps have been discovered, improving the exploration potential of the sag.