Laboratory Simulation of the Formation Process of Surface Geochemical Anomalies Applied to Hydrocarbon Exploration

作     者：WANG Guojian TANG Yuping CHENG Tongjin TANG Junhong FAN Ming LU Li 

作者机构：Wuxi Research Institute of Petroleum GeologyResearch Institute of Petroleum Exploration and ProductionSINOPEC College of Material & Environmental EngineeringHangzhou Dianzi University 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2016年第90卷第6期

页      面：2149-2162页

核心收录：

学科分类：081801[工学-矿产普查与勘探] 081802[工学-地球探测与信息技术] 081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：supported by the National Natural Science Foundation of China(grants No.41373121 and 41072099) the scientific and technological project of SINOPEC under Contract No.P05069 Support by SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms,China 

主　　题：hydrocarbon microseepage surface geochemical anomaly 3D measurement laboratory simulation migration mechanisms and processes 

摘      要：The formation mechanisms and processes of geochemical anomalies used as proxies in surface geochemistry exploration （SGE） have not been well understood. Previous studies cannot realize 3D measurement of microseeping hydrocarbons from reservoirs to the surface, which made it difficult to understand the features and pathways of deep hydrocarbon microseepages. Understanding the processes of hydrocarbon microseepages will contribute to the acceptance and effectiveness of surface geochemistry. Based on a simplified geological model of hydrocarbon microseepages, including hydrocarbon reservoir, direct caprock, overlying strata and Quaternary sediments, this work established a 3D experimental system to simulate the mechanisms and processes of deep hydrocarbon microseepes extending to the surface. The dispersive halos of microseeping hydrocarbons in the subsurface were adequately described by using this 3D experimental system. Results indicate that different migration patterns of hydrocarbons above the point gas source within the simulated caprock and overlying strata can be reflected by the ratio of i-butane to n-butane （i-C4/n-C4）, which follow diffusion and infiltration （buoyancy） mechanisms. This is not the case for vertical measurement lines far from the point gas source. A vertical gas flow in the form of a plume was found during hydrocarbon microseepage. For sampling methods, the high-density grid sampling is favorable for delineating prospecting targets. Hydrocarbon infiltration or buoyancy flow occurs in the zones of infiltration clusters, coupling with a diffusion mechanism at the top of the water table and forming surface geochemical anomalies. These results are significant in understanding hydrocarbon microseepage and interpreting SGE data.