初始模型对灰质浊积岩储层叠前AVO反演的影响研究

Study on the Effect of Initial Model in Prestack AVO Inversion of Calcareous Turbidite Reservoir

研究工区济阳坳陷滑塌浊积砂体主要发育在沙三下亚段,多含有灰质泥岩,灰质泥岩在速度和阻抗上与浊积砂岩差异不大,导致砂体识别困难。由于叠前地震数据中包含有更加丰富的振幅和旅行时信息,在识别储层上更具优势,因此,为了更加有效地识别及精细地刻画出砂体储层,本文首先通过建立灰质浊积岩储层地震地质模型,正演模拟得到理论地震数据,然后从基于不同测井数量、是否使用层位解释资料两方面出发,建立叠前AVO(Amplitude Variation with Offset,AVO)反演初始模型,探讨了初始模型对反演结果的影响;最后在对实际灰质浊积岩储层工区进行叠前AVO反演时,使用不准确的测井数据建立初始模型导致反演结果与实际测井解释不吻合,造成反演误差较大,进一步验证了叠前AVO反演中初始模型建立准确的重要性。

The slump turbidite sand bodies in Jiyang depression are mainly developed in lower Es3 sub segment,and most of them contain calcareous mudstone.The calcareous mudstone has little difference from turbidite sandstone in velocity and impedance,which leads to the difficulty of sand bodies identification.As prestack seismic data contain richer amplitude and travel time information,it has more advantages in identifying reservoirs.Therefore,in order to more effectively identify and finely depict the sand reservoir,this paper establishes a calcareous turbidite reservoir seismic geological model and obtains theoretical seismic data by forward modeling.The prestack AVO(amplitude variation with offset)inversion initial model is established based on different logging quantities and whether to use horizon interpretation data,then discusses the influence of the inversion initial model on the inversion results.When prestack AVO inversion is used in actual calcareous turbidite reservoir work area,the inversion results by establishing the initial model using inaccurate logging data are inconsistent with the actual logging interpretation,which further verifies the importance of accurate establishment of the initial model in prestack AVO inversion.