页岩气解析实验及其地质应用

The desorbing experiments of shale gas and its geological application

陕北斜坡构造带发育陆相页岩,部分页岩气开发井已经投产,但针对页岩气排烃方式、赋存过程的研究仍较薄弱,对页岩气储量的估算还存在不确定性。这些问题的解决有助于认识资源潜力、降低勘探风险。基于页岩气解析实验可以获得气体化学组成和碳同位素组成数据,其不仅为页岩气的成因研究及形成过程研究提供基础信息,还能解决上述地质机理及储量计算的问题。研究表明,研究区页岩气属于典型的油型气;页岩的吸附作用具有选择性,页岩优先吸附重烃气体和具13 C的甲烷分子;页岩气的初次运移遵循小分子组分优先运移的规律;研究区页岩气的地质赋存过程为先吸附再溶解后游离。

Lacustrine shale is well developed in the Shanbei area,and some shale gas wells have been put into production in this area.However,the researches on shale gas migration as well as storage process are very poor,the estimation about shale gas reserves is also a debatable issue for exploration.Solving the above challenges helps to recognize the resource potential,and reduce exploration risk.The gas components and carbon isotope compositions can be obtained from the desorbing experiments,and these data provide us with important information about the origins and storage process of shale gas.Furthermore,they can help to solve the problems of geological mechanisms and reserves calculations.The results show that,the shale gas in the study area is oil type gas;the heavy gases as well as methane enriched in 13 C have the priority over other components to absorb on the shale surface;the small molecules have the priority over large molecules to migrate within the shale;the formation order of different gas types is absorbing gas,dissolving gas and then free gas.