AVO流体反演技术在低孔渗砂岩气藏预测中的应用

西湖凹陷A构造的砂岩气藏，主要埋藏于3000m以下的深层，且发育于浅水沉积环境，储层物性较致密，厚度横向变化大，导致储层的AVO响应复杂，常规AVO分析难以对储层流体进行有效识别。研究了AVO流体反演技术在该构造含气储层预测中的应用。该技术在对储层以及非储层速度、密度、厚度等关键参数的统计分析的基础上，利用Monte－Carlo随机模型建立、地震正演模拟、流体替换等技术，获得储层在不同流体下AVO响应的验前概率；然后利用Bayes理论，估算实际地震数据AVO响应指示储层含某种流体的可能性一验后概率，从而实现储层流体的预测。实际钻探结果证实了该方法的有效性。

The Application of AVO Liquid Inversion Technique in Prediction of Low Porosity and Permeability Sandstone Gas Reservoirs

The sand reservoirs of structure A which locates in the Xihu Sag are mainly bur- ied more than 3000 meters, and belong to shallow water depositional systems; The physical property of the sandstone reservoir is tight, and its thickness changes quickly, so the tradi- tional AVO（Amplitude Versus Offset） technique can＇t predict the reservoir＇s fluids effec- tively. The AFI （AVO Fluid Inversion） technique is studied to predict the gas reservoirs of structure A. Based on the statistical analysis of key reservoir parameters, such as velocity, culated based on Bayes Theorem using the AVO responses of field data. Then the predic- tion of sandstone gas reservoirs can be achieved. The actual drilling shows the AVO Fluid Inversion technique is effective in tight gas reservoir prediction.