基于小波边缘分析与井-震联合建模的波阻抗反演技术在乌尔逊断陷储层预测中的应用

Application of wave impedance inversion technology based on wavelet edge analysis and well-seismic joint modeling in reservoir prediction of Wuerxun rift

针对乌尔逊断陷构造复杂、储层横向非均质性强、含油砂体小而薄预测难的问题,应用小波边缘分析与井-震联合建模的波阻抗反演技术,从地震记录中直接提取反映构造和岩性变化的地震属性特征参数,与测井声波阻抗数据一起建立初始模型并参与波阻抗模型的扰动修改。此反演技术弥补了井间插值建模过程中井间高频成分的缺失和井间岩性的局部变化细节,避免了常规波阻抗反演过程中由于初始模型不准确而产生的错误信息,提高了地震资料识别“小而薄”砂体的分辨能力。结果表明:受东部物源控制,乌尔逊断陷铜钵庙断裂带发育扇三角洲-半深湖(深湖)沉积体系;受断裂坡折带影响,在铜钵庙断层的下降盘发育一系列扇三角洲前缘砂体。实际钻井结果与钻前预测对比表明,井点处砂体顶界构造深度的相对误差小于0.3%,砂体厚度的相对误差小于3.84%,预测精度满足精细储层预测要求。研究成果可为乌尔逊断陷精细油藏描述和井位部署提供依据。

In view of complex structures,high lateral heterogeneity of reservoirs and difficult prediction of small and thin oil-bearing sand bodies in Wuerxun rift,wave impedance inversion technology of wavelet edge analysis and well-seismic joint modeling is applied to directly extract seismic attribute characteristics parameters reflecting structural and lithological changes from seismic records,and establish initial model together with logging acoustic impedance data and participate in disturbance modification of wave impedance model.This inversion technology makes up for the lack of inter-well high-frequency components and the details of inter-well local lithologic change in the process of inter-well interpolation modeling,avoiding error information caused by inaccurate initial model in the process of conventional wave impedance inversion,and improving resolution of seismic data to identify“small and thin”sand bodies.The result shows that Tongbomiao fault belt in Wuerxun rift develops sedimentary systems of fan delta-semi deep lake(deep lake)controlled by eastern provenance.Influenced by faulted slope break belt,a series of fan delta front sand bodies are developed in downthrown side of Tongbomiao fault.Comparison between actual drilling and pre-drilling prediction indicates that absolute value of relative error of structural depth on sand body top at well point is<0.3%,and absolute value of relative error of sand body thickness is<3.84%.Prediction accuracy meets the requirements of fine reservoir prediction.The research provides basis for fine reservoir description and well deployment in Wuerxun rift.