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鄂尔多斯盆地苏里格气田是迄今发现的我国最大的天然气田 ,其主要产气层段是上古生界下二叠统下石盒子组底部附近盒8段的砂岩储集层 ,钻探结果表明 ,该区是一个大面积含气同时具有明显非均质性的砂岩复合气藏。单井产气量 (无阻流量 )最小为 2× 10 4 m3 /d ,最大可达 12 0× 10 4 m3 /d ,变化非常大 ,因此 ,在储层厚度预测的基础上 ,定性或半定量预测砂岩储层的含气性 ,对于有效提高探井成功率十分重要和必要。本文在测井及地质资料综合分析的基础上 ,通过对已知井作正演模拟 ,总结其井旁地震道振幅随偏移距的变化规律 ,并利用岩性物理测定结果进行烃类检测反演 ,将本区含气砂岩组合正确归类。在苏里格气田的评价勘探中 ,把AVO技术作为该区进行钻前目标含气性预测的主要手段 ,取得了很好的应用效果。

Research and Application of AVO Technique in Sulige Gas Field

??Up to now the Sulige gas field found in E'erduosi Basin is the largest gas field in China and its main gas-producing interval is the P₁h₁⁸ sandstons reservoir at the bottom of Lower Shihezi Formation,Lower Permian,Upper Paleozoic.Drilling results indicate that this region is a composite sandstone gas reservoir with obvious heterogeneity and a large gas-bearing area.Individual-well gas producing rate (open-flow capacity) changed with a vast range from 20×10⁴m³/d (minimum) to 1200×10⁴m³/d (maximum).Therefore it is very important and imperative for raising exploration well success ratio to predict qualitatively and semiquantitatively the gas potential of the sandstone reservoir on the basis of predicting reservoir thickness.In the paper,based on comprehensively analyzing the geological and logging data,the gas-bearing sandstone groups in this region are properly classified through forward modeling the well-known wells,summarizing the change rule of amplitude versus offset (AVO) of the seismic traces beside wells and carrying out the hydrocarbon detecting inversion by use of petrophysical measure results.In the evaluation exploration for Sulige gas field,a good result of applying the AVO technique,which has been taken as the major means,to predicting the gas potential of the targets before drilling has been obtained in this region.