摘要
针对鄂尔多斯盆地中部地区长_(7)段页岩热演化偏低以及页岩气赋存特征复杂的问题,利用基本地球化学方法以及气体解析实验开展对比性研究,揭示页岩气的地球化学特征,探索页岩气的赋存过程。研究结果表明:页岩的有机质类型主要为Ⅰ型和Ⅱ1型,热演化程度为中等,有机碳含量平均为4.52%,游离烃含量为4.09 mg/g,热解烃含量为8.70 mg/g;研究区页岩气属于油型气,其地质成因为热解成因;页岩气的赋存相态为游离气、溶解气和吸附气共存,且吸附气含量和溶解气含量之和大于游离气含量;页岩对不同气体的吸附性能具有较大差异,对氮气的吸附性最弱;烃类气体中,小分子气体的初次运移能力强于大分子气体。由于热演化程度偏低,一方面使得页岩内部油气水共存,整体含气性不高,另一方面使得油气在地质运动过程中得以大量保存。在针对长_(7)段的开发过程中,进行页岩油气的共同开发最具有现实意义和经济价值。研究结果对长_(7)段下步勘探开发具有一定的指导意义。
In view of the low degree of thermal evolution and complicated shale gas occurrence of the Chang_(7) Member in the central Ordos Basin,a comparative study was conducted with basic geochemical methods and gas analysis experiments to discover the geochemical characteristics of shale gas and explore the occurrence process of shale gas.The results showed that the shale mainly contained TypeⅠand TypeⅡ1 organic substances,with moderate thermal evolution,average organic carbon content of 4.52%,free hydrocarbon content of 4.09 mg/g,and pyrolysis hydrocarbon content of 8.70 mg/g;the shale gas in the study area was petroliferous gas,and its geological origin was thermal decomposition;the occurrence state of shale gas was coexistence of free gas,dissolved gas and adsorbed gas,and the sum of adsorbed gas content and dissolved gas content was greater than free gas content;the adsorption of shale for different gases was quite different,and its adsorption for nitrogen was the weakest;as for the hydrocarbon gases,the initial migration capacity of small molecule gases was greater than that of macromolecular gases.Due to the low thermal evolution,on the one hand,oil,gas and water coexisted in the shale,generally low gas content in shale is not high.On the other hand,a large amount of oil and gas was preserved in geological movement.In the development process of Chang_(7) Member,joint development of shale oil and gas is of the most practical and commercial significance.There is much for reference of the study results to the further exploration and development of Chang_(7) Member.
作者
霍萍萍
范柏江
王妍妍
梁全胜
李亚婷
王霞
师良
Huo Pingping;Fan Bojiang;Wang Yanyan;Liang Quansheng;Li Yating;Wang Xia;Shi Liang(Yan′an University,Yan′an,Shaanxi 716000,China;Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi′an,Shaanxi 710000,China)
出处
《特种油气藏》
CAS
CSCD
北大核心
2021年第2期49-56,共8页
Special Oil & Gas Reservoirs
基金
陕西省教育厅科学研究专项“滑塌浊积体储层的孔喉特征与微观控制要素”(19JK0968)
延安大学大学生创新创业项目“延安周边地区页岩油赋存条件与有利区优选”(202010719066)。
