砂岩成岩相地震预测--以松辽盆地齐家凹陷青山口组为例

Seismic prediction of sandstone diagenetic facies:Applied to Cretaceous Qingshankou Formation in Qijia Depression,Songliao Basin

以松辽盆地齐家凹陷青山口组为例,探讨应用地震沉积学和实验室岩心分析手段,采用常规三维地震资料预测砂岩成岩相的可行性。用地震资料划分地层和成岩相单元、建立岩心成岩相与地震属性的联系以及寻找有效的地震成岩相成图方法,是地震成岩相研究的3个关键步骤。井-震高分辨率层序分析和地层切片的制作可提供储集层尺度(20 m)成岩相单元的合理载体。砂岩成岩相分析和成岩序列的建立可揭示影响储集层质量的最重要因素——成岩作用。通过储集层参数和岩石物性分析可进一步了解成岩作用和波阻抗的关系并筛选适用地震检测的主要成岩作用。地震岩性体(如90°相位地震体)转换提供了成岩相的振幅(波阻抗)检测信号,用地震岩性体制作的地层切片可用于识别沉积相。在沉积相图上分析沉积相、波阻抗和成岩相的关系,可最终形成地震成岩相图。对青山口组泥质胶结砂岩和方解石胶结砂岩的实际分析表明,虽然砂岩成岩相地震检测尚处于起步阶段,但目前用常规三维地震资料预测砂岩成岩相是可行的。

Seismic diagenetic facies is an important control factor on reservoir quality. This study investigated the possibility and feasibility of predicting sandstone diagenetic facies with conventional 3D seismic data by seismic sedimentology, calibrated by lab core analysis data in the Qijia area of the Songliao Basin. There are three core issues related to seismic characterization of diagenetic facies, including how to correlate stratigraphic and diagenetic units from seismic data, how to evaluate relationship between core-based diagenetic facies and seismic attributes, and how to fmd an effective way to map seismic diagenetic facies. Well- and seismic-based high-resolution sequence analysis and seismic stratal slicing provided reservoir-scale （20 m） seismic representations of diagenetic units. Core-based analyses of sandstone diagenetic processes and diagenetic sequence revealed that the diagenesis has the most important influence on reservoir quality. An investigation of reservoir parameters and acoustic rock properties further disclosed link between diagenetic facies and impedance, leading to the recognition of calcite cementation as a process that can be detected by seismic data. Seismic-based lithology cube （e. g., 90°-phased seismic volume） provided amplitude （impedance） signal for detection of diagenetic facies The stratal slices made from the seismic-based lithology cube were used to interpret depositional facies and systems. Eventually, a seismic diagenetic facies map was generated by analyzing relationships between depositional facies, impedance, and diagenetic facies. The case study of the clay-cemented sandstone and calcite-cemented sandstone in the Qijia area showed that although being in its infant stage with many difficulties, the seismic detection of sandstone diagenetic facies with conventional seismic data is not only possible, but also feasible.