“两步法反演”技术在致密砂岩气藏预测中的应用——以苏里格气田苏X区块为例

苏里格气田苏X区块石河子组盒8段为致密砂岩储层,具有低孔、低渗、低丰度且非均质性严重等特点,而且有效砂体重叠模式复杂、连通性差,气水关系复杂,不同含气、含水砂岩之间无统一的气水界面。如何应用地震技术预测含气有利区成为该区块天然气开发所面临的主要难题之一。在综合分析目的层储层地质特征和地球物理特征的基础上,探索了＂两步法反演＂含气性预测技术,首先应用分频反演方法预测砂体富集区,在此基础上利用波阻抗反演方法预测砂岩的含气性,再将2种方法预测的结果有机地结合,预测出苏X区块盒8段的含气有利区。实际应用表明,该方法在一定程度上减少了多解性,提高了预测的准确性,能够有效地预测出含气有利区。

Application of "two step inversion" technology to the prediction of tight sandstone gas reservoir: A case study from Su X block in Sulige Gas Field

The tight sandstone reservoir is developed in the eighth member of Shihezi Formation in Su X block of Sulige Gas Field. The reservoir has the characteristics of low porosity, low permeability, low abundance and strong heterogeneity. It has complex overlapping pattern of sand bodies, complex gas and water relationship and non-uniform air-water interface between gas and water-bearing sands. How to apply seismic technology to predict favorable gas-bearing areas becomes one of the main problems in this block. Based on comprehensive analysis of reservoir geologic features and geophysical characteristics, this paper explored the ＂two step inversion＂ technology for predicting favorable gas-bearing areas. Firstly using frequency division inversion method to predict sand body enrichment area, and then using wave impedance inversion to predict gas-bearing properties of the sand, and finally combining the two methods to predict favorable gas- bearing areas of the eighth member of Shihezi Formation in Su X block. The practical application indicates that this method reduces the multiple solutions and improves the accuracy of prediction, and can be used to predict favorable gas bearing area effectively.