海底烃类气体渗漏实验模拟:烃类气体含量及分子组成变化与渗漏过程重建

EXPERIMENTAL SIMULATION OF SEABED HYDROCARBON GAS SEEPAGE:VARIATION OF CONTENT AND MOLECULAR COMPOSITION OF THE HYDROCARBON GAS AND RECONSTRUCTION OF SEEPAGE PROCESS

利用海底烃类气体渗漏实验模拟装置对海底烃类气体渗漏过程进行了实验模拟。通过10个采样口样品采集和分析测试,探讨了各采样口在渗漏过程中烃类气体含量和分子组成变化。各采样口烃类气体含量和分子组成随时间具有明显阶段变化,总体显示了两阶段渗漏特征:第1渗漏阶段从7月13日到8月5日,第2渗漏阶段从8月6日到9月25日。根据各采样口烃类气体在两阶段渗漏强度可分为3类:第1类包括S1、S2、S5、S7和S8,表现为在第1阶段和第2阶段渗漏强度均不高,属于微渗漏类型;第2类包括S3、S4和S9,表现为在第1阶段渗漏强度低,属于微渗漏类型,在第2阶段渗漏强度高,属于宏渗漏类型;第3类包括S6和S10,表现为在第1阶段和第2阶段均属于宏渗漏类型。烃类气体渗漏主要受实验柱体内各种界面和沉积物粒度等因素控制,而且不同采样口渗漏烃类气体含量变化的控制因素也不尽相同。模拟结果为研究海底烃类气体渗漏过程中,断裂构造、地层不整合界面、岩性差异界面,以及沉积物粒度变化等对海底烃类气体渗漏控制机理提供了实验依据。

The experimental simulation for seabed hydrocarbon gases seepage was carried out by the authors.The changes in contents of hydrocarbon gases and their molecular compositions during the seepage were studied through sample collection and analysis at 10 sampling outlets.It is found that the hydrocarbon gas content and molecular composition of each sampling outlets have obvious phase changes with time.There are two stages of seepages in general,the first stage from July 13 to August 5,and the second stage from August 5 to September 25.According to the intensity of seepage,the sampling outlets can be divided into three categories.The first category includes S1,S2,S5,S7 and S8,during which the seepage intensity is not high and thus named as the micro-seepage type in the first and second seepage stages.The second category includes S3,S4 and S9,of which the seepage intensity is low and belonging to micro-seepage type in the first seepage stage,and high in second seepage stage and thus named the type of macro-seepage in this paper.The third category includes S6 and S10 with high seepage intensity and belongs to macro-seepage type.In the process of experimental simulation,hydrocarbon gas seepage is mainly controlled by various interfaces inside the experimental column and sediment grain size.The control factors for hydrocarbon gas seepage at different sampling outlets are different.The simulation results provided the experimental basis to the study of controlling factors and mechanisms of hydrocarbon gas seepage on seabed,such as fault structures,unconformities,lithological boundaries as well as changes in grain size.