泥岩盖层封气性演化阶段及其研究意义

在研究泥岩盖层封气性的形成条件及演化特征的基础上 ,对 3种类型泥岩盖层的封气性演化阶段进行了划分 :既无生气能力又无异常孔隙流体压力的泥岩盖层 ,其演化不存在阶段性 ,仅有毛细管封闭 ;具生烃能力但不具异常孔隙流体压力的泥岩盖层 ,其演化可分为毛细管封闭和毛细管 压力封闭两个阶段 ;既具生烃能力又具异常孔隙流体压力的泥岩盖层 ,其演化可分为毛细管封闭、压力封闭 毛细管封闭 抑制封闭和毛细管封闭 替代封闭 3个阶段。研究泥岩盖层封气性演化阶段 ,可以正确评价泥岩盖层的封气能力及其有效性。以松辽盆地三肇凹陷青山口组和泉头组一、二段两套泥岩盖层为例 ,讨论了泥岩盖层封气性演化阶段的划分及其意义

GAS CONFINING EVOLUTION OF MUDSTONE SEALS AND ITS SIGNIFICANCE

Based on a study of gas confining origin and evolution of mudstone seals,three types of gas confining evolution have been recognized:(1)For the mudstone with neither gas generating ability nor abnormal pressure,its gas confining is only a capillary sealing,and there is no evolution stages. (2)For the mudstone with gas generating ability and normal pressure,there are two stages of gas confining evolulion,i.e.capillary sealing and,capillary pressure sealing. (3)For the mudstone with gas generating ability and abnormal pressure,there may be three evolution stages of gas confining,i.e.capillary sealing,capillary pressure restraining sealing and capillary replacing sealing.The study of gas confining evolution of mudstone seals can be used to evaluate gas confining ability and its efficiency.As a study case,this paper has discussed gas confining evolution stages and their significance for two mudstone seals of Qingshankou(K 1qn) and Quantou (K 1q 1 2 ) Formation in Sanzhao Sag,Songliao Basin.