油页岩的地震识别与评价技术

A seismic technique for recognition and evaluation of oil shale

松辽盆地上白垩统青山口组和嫩江组沉积时期发育未成熟油页岩,为提高其勘探效率并降低其勘探成本,利用地震正演-反演方法识别与评价油页岩。通过油页岩的微观孔隙、岩石组分及其地球物理响应分析,建立油页岩的等效岩石物理模型和地震波阻抗响应方程;采用合成记录法正演模拟地震资料的油页岩分辨能力,建立油页岩的楔形收敛地质模型;利用测井约束地震反演与神经网络算法运算,获取波阻抗和有机质反演数据体。研究结果表明:有机质和孔隙发育程度影响油页岩的地震响应;地震资料可分辨最小油页岩厚度为6.4 m;波阻抗反演结果只能定性评价油页岩发育的空间展布特征,而有机质反演结果不仅能预测油页岩发育的空间展布特征,还可以评价油页岩发育的品质。

The immature oil shale is evident in the Upper Cretaceous Qingshankou and Nenjiang formations of the Songliao Basin. The seismic technique was employed to recognize and evaluate oil shale, to improve exploratory efficiency and save on exploratory costs. An equivalent rock physical model and the wave impedance equation were established for oil shale based on the analysis of microscopic pores, macerals and their geophysical responses. Seismic forward modeling was used to research the seismic resolution of oil shale on the basis of synthetic recording. A geological model of converging wedge was established for oil shale. According to the method of logging-constrained inversion and neural network algorithm, the inverted volumes of wave impedance and organic matter were obtained. The results show that the seismic response of oil shale is influenced by organic matter and pore abundance. The seismic data can be used to distinguish minimum thickness with 6.4 m for oil shale. The inverted data of wave impedance can be employed to qualitatively evaluate the distribution of oil shale. However, the inverted organic matter volume is used not only to predict the distribution ofoil shale, but also to evaluate the quality ofoil shale.