泥页岩中水的赋存态研究进展及其意义

Research Progress and Significance of the Occurrence of Water in Shale

泥页岩中的水具有多种赋存态,明确其赋存形式、各赋存态水的含量及其分布特征,有利于进一步理解“油(气)—水—岩石”之间的内在联系,对页岩油气的生成、存储、运移和勘探开发具有重要的指导意义。目前关于泥页岩中不同水的分类繁杂且不统一,综合现有的划分方法,提出基于水的赋存态将其划分为自由态的可动水、体积充填态的毛管束缚水、表面吸附态的水膜束缚水以及离子态的结构水4种类型。其中,束缚水是油气存储空间的“竞争者”和运输通道上的“障碍物”,水膜束缚水主要占据页岩油气的有效吸附位,而毛管束缚水则会堵塞部分小孔道。同时,水的赋存态会随矿物和有机质的自身变化而发生改变,从而影响储层的润湿性和页岩油气的勘探开发。此外,探讨泥页岩中矿物、有机质和孔隙性质对水的赋存机制的影响,并调研热分析和核磁共振等检测方法以研究泥页岩中不同赋存态水的含量、位置以及微观分布特征,以期为页岩油气的高效开发提供理论基础。

Clarifying the occurrence,form,content,and distribution of water in shale is conducive to further understanding the internal relationship between“oil(gas)-water-rock”.This line of research has implications in guiding the generation,storage,migration,exploration,and development of shale oil and gas.Considering that the current classification of different waters in shale is complex and inconsistent,a classification approach based on the occurrence state of water is proposed combined with existing classification methods.Specifically,it categorizes water into free-state movable water,volume-filled capillary-bound water,surfaceadsorbed bound water film,and structured water of ionic state.Irreducible water is the“competitor”of the storage space and an“obstacle”in the transportation channel for oil(gas).The bound water film occupies the effective adsorption sites of shale oil and gas,and the capillary-bound water blocks small pores and throats.Simultaneously,the occurrence state of water changes with changes in the minerals and organic matter,thus affecting the wettability of the reservoir and the exploration and development of shale oil and gas.In addition,the influence of minerals,organic matter,and pore characteristics on the occurrence-related mechanisms of water in shale were discussed,and thermal analysis and nuclear magnetic resonance detection methods were applied to understand the content,location,and microscopic distribution characteristics of different occurrences of water.This was done to provide a theoretical basis for the efficient development of shale oil and gas.