页岩气藏超低含水饱和度形成模拟及其意义  

Simulation of utlra-low water saturation in shale gas reservoirs and its significance

作　　者：方朝合[1,2,3] 黄志龙[1] 王巧智[4] 游利军[4] 康毅力[4] 王义凤[1] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]国家能源页岩气研发(实验)中心,河北廊坊065007 [3]中国石油集团非常规油气重点实验室,河北廊坊065007 [4]油气藏地质及开发工程国家重点实验室,西南石油大学,四川成都610500

出　　处：《地球化学》2015年第3期267-274,共8页Geochimica

基　　金：国家科技重大专项(2011ZX05018);国家重点基础研究发展计划项目(2013CB2281)

摘　　要：页岩气属于非常规天然气,资源丰富,开发潜力巨大。含水饱和度是控制致密气藏持续生产最关键的储层参数,然而现阶段对页岩气成藏中超低含水饱和度是否存在尚存在疑问。选取川渝地区页岩露头岩样,采用气驱法模拟了成藏过程中含水饱和度变化,结合川南页岩气储层地质特征,建立了生烃排驱的地质模型,提出了气携液的概念模型。结果表明,页岩气藏存在超低含水饱和度现象;页岩气成藏过程中大量生烃产生排驱效应与气携液作用,有利于页岩气储层超低含水饱和度的形成,气携液作用、裂缝和高温环境加速了含水饱和度降低;超低含水饱和度增加页岩气储层吸附能力,增大储层可流动孔喉范围,提高气相传输能力,但在工程作业过程中加大水相渗吸速率,强化水相滞留效应,使页岩气藏水相圈闭损害潜力更大。在页岩气有利区评价、气藏钻完井、开发过程中,须倍加重视超低含水饱和度这一客观事实和其衍生的工程作业问题。Shale gas as unconventional resource shows huge potential for exploration. The most critical parameter for shale gas reservoir is its water saturation, as it controls the tight gas reservoir＇s continuous production. There still is a controversial debate about the formation process of ultra-low water saturation in shale gas accumulation process and the geological and engineering significance. In this study, shale outcrop samples from Sichuan and Chongqing basins were used, simulation experiments of water displacement via gas injection were conducted, and the variety of water saturation was investigated in the course of hydrocarbon migration and accumulation. Based on the geological characteristics of southwestern Sichuan basin, the authors established a geological model for hydrocarbon charging and a conceptual model for liquid loading in evaporation. The results indicate that： （1） The accumulation process can help shale gas reservoirs to develop ultra-low water saturation; （2） Liquid loading in evaporation, fracture and high temperature can accelerate the process of decreasing water saturation; （3） Ultra-low water saturation can strengthen the capability of adsorption, extend the scope of movable pore throat and raise gas-mass-transfer capacity. In practical engineering operation, occurrence of ultra-low water saturation can accelerate imbibition, even enhance the effect of aqueous phase trapping which largens the potential on aqueous trapping damage of shale gas reservoirs. While in drilling, completion, exploration and evaluation of favorable areas, more attention should be paid on the objective fact of ultra-low water saturation and engineering damage.

关 键 词：页岩 超低含水饱和度 生烃充注 汽化携液 裂缝 

分 类 号：P593[天文地球—地球化学]