苏里格气田低阻砂岩储层的含气性预测研究

Research on gas-bearing prediction using AVO in sandstone reservoir with low-impedance,Sulige gas field

鄂尔多斯盆地苏里格气田是我国迄今发现的最大的天然气田 ,其主要产气层段为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 ,属典型陆相沉积的薄互层储层。基于大井距 (10～ 15 km)的评价钻探结果表明 ,该区是一个大面积含气但同时具有明显非均质性的砂岩复合气藏。在近万平方千米的勘探区域内 ,钻井揭示的含气层厚度最大达 15～ 2 0 m,而最小却只有 1～ 2 m,单井产量 (无阻流量 )最小为 2× 10 4 m3/ d,最大可达12 0× 10 4 m3/ d。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。在测井及地质资料综合分析的基础上 ,通过正演模拟 ,研究该区盒 8储层在地震资料中的 AVO响应 ,并利用岩石物性测定结果进行烃类检测反演 ,是该区进行钻前目标含气性预测的主要手段。在实际应用中 ,取得了较好的应用效果。

Sulige gas field is the biggest gas field of China found in Ordos Basin up-to-now,which main gas producting formation is sandstone reservoir of He 8 Member,near the bottom of Upper Paleozoic Lower Permian Lower Shihezi Formation,belonging to thin-interbedded reservoir of typical continental sedimentation.Appraisal well results based on large hole spacing (10～15km) show that the area is composite sandstone gas reservoir both gas-bearing with large area and typical heterogeneous.In nearly 10000km 2 exploration area,the maximum thickness of gas-bearing layer revealed by drilling is 15～20m,while minimum is only 1～2m;min-production of single well (non-resistant flow) is 2×10 4m 3/d and maximum can reach to 120×10 4m 3/d,varying in a large scope.Therefore,on the basis of prediction of reservoir thickness,qualitative or semi-quantitative gas-bearing prediction of sandstone reservoir is very important and necessary to effectively improve success rate of exploration well.On the basis of integrative analysis of logging and geologic data and through forward modeling,studying the AVO response of He 8 reservoir in seismic data and using petro-physical measuring results for inversion of hydrocarbon detection are major tools for gas bearing prediction of pre-drilling targets in the area,which gained better applied results in practice.