摘要
页岩孔隙的含水性特征直接影响页岩气的赋存、富集和开发。以扬子地区YQ1井龙马溪组和FY1井牛蹄塘组高成熟度海相页岩为例,基于干燥条件下页岩的孔隙结构参数和实取状态下页岩孔隙水的含量,通过理论计算初步研究了水在页岩不同孔隙中的分布和赋存相态。结果表明,页岩有机孔中的水可能只填充到有机微孔中,而有机非微孔中不含水;页岩无机孔中的水主要填充到无机微孔中和以单分子层吸附在无机非微孔孔壁上,少量的孔隙水会以双分子层和多分子层吸附在无机非微孔孔壁上。高成熟度海相页岩的孔隙水对微孔的影响程度显著大于非微孔,对无机孔的影响程度显著大于有机孔。实取状态下,页岩有效的比表面主要来自于有机孔,导致吸附气主要储存在有机孔中;页岩有效的孔容来自有机孔和无机孔的共同贡献,导致两类孔隙中均含有游离气。虽然YQ1龙马溪组和FY1牛蹄塘组页岩中水占孔隙结构的比例相似,但FY1页岩有效的孔隙结构中无机孔隙结构的占比更大,这可能也是造成牛蹄塘组页岩含气性较差的原因之一。
Water-bearing characteristics of shale nanopores directly influence the distribution, accumulation, and exploitation of shale gases. Based on the pore structure of shales under dried conditions and the pore water contents under as-received conditions, this study investigated the distribution and occurrence phases of pore water in various nanopores of the YQ1 Longmaxi Formation and the FY1 Niutitang Formation shales in the Upper Yangtze area. The results indicate that all the pore water in the organic matter hosted(OM) pores of shales is stored in the OM micropores in the capillary-filling phase, while the OM non-micropores are free of pore water.The majority of the pore water in the inorganic matter hosted(IM) pores of shales is stored in the IM micropores in the capillary-filling phase and adsorbs on the IM non-micropore surfaces in the monomolecular layer phase,while a small amount of the pore water adsorbs on the IM non-micropores surfaces in double-molecular or multimolecular layer phases. The influence of pore water on the micropores and IM pores is more significant than that on the non-micropores and the OM pores, respectively. The effective pore surfaces for the adsorption of shale gases are mainly contributed by the OM pores of shales, which results in the adsorbed shale gases being dominantly stored in the OM pores. Though the effective pore volumes of the shales are co-contributed by the IM and OM pores, most of the free gases may be stored in the IM pores resulting from the strong adsorption of OM pores on shale gases. The total effective pore structures are similar for the YQ1 and FY1 shales, however, the effective pore structures of the FY1 shales are more significantly contributed by the IM pores, which may be one of the reasons for the lower GIP(gas-in-place) contents of the Niutitang Formation shales.
作者
程鹏
吴伟
高海涛
罗超
刘燊阳
田辉
CHENG Peng;WU Wei;GAO Haitao;LUO Chao;LIU Shenyang;TIAN Hui(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;Shale Gas Institute of PetroChina Southwest Oil&Gasfield Company,Chengdu 610051,Sichuan,China)
出处
《地球化学》
CAS
CSCD
北大核心
2022年第5期503-515,共13页
Geochimica
基金
国家自然科学基金(41925014、U1810201)
广东省自然科学基金(2021A1515011381)
中石油西南油气田课题(XNS-YYY-JS2021-49)联合资助。
关键词
高成熟度
海相页岩
孔隙结构
孔隙水分布
水的赋存相态
overmature
marine shales
pore structures
pore water distribution
water occurrence phase
