基于绕射信息提取技术的断裂识别方法及应用

Research and application of fracture identification method based on diffraction information extraction technology

鄂尔多斯盆地A区块的地质、地震特征表现为:地表条件复杂,致密气储层非均质强、厚度小,不同井的气层测试产量差异很大,断层、裂缝影响油气富集并具有后期调整、再分配气层分布的作用;地震资料分辨率低,常规叠后数据难以满足薄储层中断层、裂缝体系识别的需求。为此,首先利用基于L0范数稀疏反演的压缩感知地震资料处理方法提高数据分辨率,为后续薄储层中断裂体系识别创造良好的资料条件。在此基础上探索基于中值滤波技术的绕射信息提取方法,在保幅偏移地震数据体上提取绕射信息,得到清晰的断点和断层信息;根据绕射波地震数据振幅及相位在空间上的不连续性,通过蚂蚁体追踪刻画断层和裂缝分布。结果表明:处理后的数据分辨率得到有效提高,并且断点清晰,更易识别断层;与常规叠后属性相比,基于绕射信息提取技术的断裂识别方法能够识别更小尺度的断裂;对比钻井气层解释结果、产能资料与绕射断裂识别结果发现,断裂和气层同时存在时产能较高,该认识可为井位部署提供重要依据。

Block A in Ordos Basin features complex surface conditions,strong heterogeneity and small thickness of tight gas reservoirs,great difference in the tested gas yield of different wells,and oil and gas enrichment influenced by faults and fractures which can adjust gas reservoir distribution later.Regarding its seismic characteristics,the resolution of seismic data is low,and conventional post-stack data is difficult to meet the needs of fault and fracture system identification in thin re-servoirs.In view of the above,the seismic data is first processed by compressed sensing based on L0-norm constrained sparse inversion to improve the data resolution,which creates good data conditions for subsequent fracture system identification in thin reservoirs.On this basis,the diffraction information extraction based on the median filtering technology is explored and then applied in the seismic data subjected to preserved-amplitude migration to provide clear fault point and fault information.Finally,according to the spatial discontinuity of diffraction amplitude and phase in seismic data,the distributions of faults and fractures are characterized by ant tracking technology.The results show that the data resolution after processing is improved significantly,with the fault points being clear,which makes fault identification easier.Compared with conventional post-stack attributes,fracture identification based on diffraction information extraction is effective for even smaller-scale fractures.The results of fracture identification based on the diffraction information extraction are compared with the interpretation results of gas la-yers in the drilled wells and productivity data,and the productivity is found higher when fractures and gas layers coexist.This finding can provide an important basis for well location deployment.