中文摘要：

随着鄂尔多斯盆地靖边气田扩边勘探的深入，在靖西地区奥陶系中组合白云岩储层中已发现多个含气区，但各含气区天然气的富集程度差异明显，尤其以靖西中部最为明显，有关这种富集差异的原因尚未开展深入研究。为此，借助钻井岩心、测井及储层物性等地质资料，从天然气充注能力、输导通道连通性、储层发育特征等方面对比分析了靖西中部地区苏127、苏203及桃15等3个区块天然气成藏特征的差异，从而探讨了靖西中部地区天然气富集差异原因，并对有利勘探方向进行了预测。结果表明，靖西中部地区苏127区块-苏203区块-桃15区块天然气富集的差异主要由下列因素造成：供烃窗口处的天然气充注能力决定了天然气富集程度；中组合储层输导通道的连通性影响了天然气聚集成藏的位置；储层的物性控制了天然气聚集成藏的规模。综合分析认为，苏127区块北部-苏203区块-桃15区块南部的马五。亚段-马五。亚段为有利勘探区；马五，亚段-马五10亚段勘探潜力相对较差。

英文摘要：

During the progressive exploration of the Jingbian Gas Field in the Ordos Basin, multiple gas- bearing regions have been discovered in the dolomite reservoirs in the Middle Ordovician assemblages of Ordovician in the Jingxi area,but these gas-bearing regions are significantly different in terms of gas en- richment degrees, especially in the midland of Jingxi area. However, the reasons for it have not been figured out.On the basis of drilling data,logging data, reservoir data and other geological data, we compared the characteristics of natural gas accumulation of three areas in the midland of Jingxi area and analyzed the main factors controlling the gas accumulation.It is shown that the natural gas accumulation of the study ar- ea is mainly controlled by the following factors. Firstly, gas charging capacity of hydrocarbon-supplying windows controls natural gas enrichment degree.Secondly, the connectivity of transporting pathway affects the position of natural gas accumulation. And thirdly,the pore ratio and permeability of reservoir control the scale of natural gas accumulation.It is concluded that Ma5^5 and Ma5^6 sub-members are favorable explora- tion areas in the north of Su127 area,Su203 area and the south of Taol5 area,and the exploration potential of Ma5^7-Ma5^10 sub-member is relatively poor.