海陆过渡相页岩气储层特殊性--以大城地区山西组为例

Shale Gas Reservoir Particularity of Shanxi Formation in Dacheng Shanxi Marine-continental Facies

随着南方海相页岩气开发取得突破，华北地区海陆过渡相?陆相页岩气也逐渐受到重视。通过实验测试分析，以大城地区山西组页岩气储层为例，分析海陆过渡相页岩气储层的特殊性。研究认为大城地区山西组沉积环境为下三角洲平原分流间湾；储层黏土矿物平均含量为56.24%，石英等脆性矿物平均含量为42.13%;T0C平均为1.85%，有机质类型主要为IH型干酪根为主，成熟度平均为1.09%;泥页岩发育两类不同类型的孔隙。对比海相焦石坝龙溪组和陆相鄂尔多斯延长组7段储层特征，表明海陆过渡相山西组泥页岩厚度小、层数多为特征，有机地化和矿物组成等均与海相与陆相页岩气储层存在显著差异。山西组页岩气储层发育基础、有机地化和物质组成条件均较为良好，页岩气保存条件较好。山西组页岩气、煤层气与致密砂岩气叠置成藏，具有丰富的资源潜力，具有联合开采的资源基础。

With the breakthroughs in the development of marine shale gas in southern China,the marine-contin-netal transitional and continental shale gas in North China have also obtained much more attentions.The particulari-ties of marine-continental shale gas reservoir have been analyzed by experiments,in which the shale of Shanxi For-mation in Dacheng area was taken for an example.The results indicated that the sedimentary environment of the Shanxi Formation shale in Dacheng area is shallowed inter-distributory bay of the lower delta plain.The total organ-ic matter content of the shale is1.85%on average.The main types of organic matter in shale is type IH,and the vitrinite reflectance is1.09%on average.The content of clay minerals in Shanxi Formation shale is about56.24%,and the brittle mineral accounts for42.13%of the total mineral content.There are mainly two different types of pores in shale.Comparied to the reservoir characteristics of the marine shale of Long Maxi Formation in JiaoShiba and that of continnetal shale of Yanchang Formation in Erdos basin,the single layer thickness of the Shanxi Formation shale is small,but the thickness of total shale in Shanxi Formation is very large,and the organic geochemical characteristics and mineral composition of Shanxi Formation shale in Dacheng area are quite different.The reservoir characteristics,organic geochemical characteristics and mineral composition of Shanxi Formation shale are all conducive to shale gas accumulation,and preservation conditions are also ideal.As shale gas,coalbed methane and dense sandstone gas are adjacent in the Shanxi Formtion,the co-exploration of shale gas,coalbed methane and dense sandstone gas in Shanxi Formation shows good prospects.