鄂尔多斯盆地延长探区陆相页岩气勘探

Continental Shale Gas Exploration and Discussion on Issues Related to Geological Theory in Yanchang Exploration Area,Ordos Basin

鄂尔多斯盆地延长探区的柳评177井压裂出气,标志着中国陆相页岩气的成功发现,揭开了我国陆相页岩气勘探开发的序幕。之后,延长石油集团在页岩气勘探方面做了大量的研究工作,取得一系列重要的地质认识,为陆相页岩气勘探开发奠定了基础。鄂尔多斯盆地晚三叠世早、中期湖盆演化控制着页岩气源岩的形成;在延长探区内,主力生烃层为长7和长9页岩,其有机质丰度较高,干酪根主要为Ⅱ1型,处于成熟—湿气(原油伴生气)阶段;所发现的页岩气均为腐泥型干酪根热演化形成的油型气,页岩中油气共生,以湿气为主,以游离态、吸附态和溶解态等形式赋存,且以游离态为主,吸附态次之;结合鄂尔多斯盆地勘探实践,针对盆地页岩气勘探相关地质问题进行了讨论,最终得出盆地热演化差异性、低熟油气生成机理以及生烃期古地层压力研究是鄂尔多斯盆地页岩气勘探地质研究的关键理论问题。

The well Liuping-177 in Yanchang exploration area achieved success of fracturing and ignition as the first continental shale gas well in Ordos Basin of China which has opened the prologue of shale gas exploration ＆ development and exploration results are remarkable.On the basis of the vast majority of research work done on shale gas exploration,the conclusions are as follows：The Ordos Basin evolution in early and middle stage of Late Triassic has controlled the geochemical characteristics and thermal evolution degree of shale gas source rocks in Ordos Basin;the genetic type of shale gas is oil-type gas produced by sapropelic-type organisms;the main hydrocarbon-generation rocks are shale from Chang-7and Chang-9members of Yanchang Formation and the type of kerogen mainly isⅡ1type with high abundance of organic matter,which stands in mature stage of moisture;the occurrence form of shale gas occurs mostly in the free state,the adsorption state and the dissolved state,and the priority is free state but adsorption state takes second place;the thermal evolution of gas source rocks is in the stage of that given priority to moisture coexisted with shale oil.In addition,on the basis of summarizing and absorbing the geological understanding of shale-gas exploration home and abroad,combined with exploration practice in Ordos Basin,the geological issues related to shale gas exploration in basin have been discussed;the key geological theory research problems of shale gas exploration in Ordos Basin are pointed out that the variation of basin thermal evolution,generation mechanism for low-mature hydrocarbon and paleo-formation pressure.