水对过成熟页岩中超临界气体吸附的影响

Shale gas is accumulated in the form of free phase and adsorbed phase，a profound understanding of the physicochemical properties and controlling factors of this two types of shale gas is of importance for accurate assessment of shale gas-in-place. Water acts as a critical impact on the formation and evolution of shale gas, and its effect on gas sorption in shales is insufficiently studied, which has become a critical constraint on gas-bearing evaluation of shales. The characterization and influential factors of gas sorption in overmature shales will be investigated in this project based on a series of gas adsorption experiments and computational simulaitions. This project focuses on the occurrence mode of water and gas sorption process in overmature shales as to bring insight into the mechanism of the effects of water vapor and liquid water on gas sorption. Furthermore, the gas sorption model under hydrous and anhydrous conditions is expected to be established based on the relationships between the sorption parameters and the moisture, temperature and pressure via combining the sorption isotherms and theoretical calculations. A geological model of shale gas which is constructed by combination of gas sorption model and PVT simulation technique is lastly applied to assess the property and evolution of shale gas, so as to provide theoretical basis for the objective evaluation of shale gas-in-place.

页岩气主要赋存形式为游离态和吸附态， 深刻认识这两种赋存态页岩气的物理化学性质及主控因素对客观评价页岩原地气量具有重要意义。水是页岩气形成和演化过程中最常面临的一个影响因素，其对页岩中气体吸附的影响作用一直缺乏深入研究，严重制约页岩含气评价。本项目拟通过开展系列气体吸附实验和计算模拟，研究气体在过成熟页岩中的吸附特征及影响因素。本项目重点研究过成熟页岩中水的赋存模式和气体吸附行为，探讨水蒸气和液态水对气体吸附的影响机制。此外，基于吸附等温线和理论计算，通过确立吸附参数与含水率及温度压力的关系进而建立含水和干燥条件下的气体吸附模型。最后，结合气体吸附模型和PVT模拟技术构建页岩气地质模型，进而评价页岩含气特征及其演化规律，为客观评价页岩原地气量提供理论依据。