烃类垂向微渗漏近地表显示与运移通道的关系——以苏北盆地盐城凹陷朱家墩气田为例

RELATIONSHIP BETWEEN NEAR-SURFACE EXPRESSIONS OF HYDROCARBON MICROSEEPAGE AND MIGRATION PATHWAYS—A CASE STUDY IN THE ZHUJIADUN GAS FIELD, THE YANCHENG SAG, THE NORTHERN JIANGSU BASIN

王国建 程同锦 卢丽 任春 陈红宇

Wang Guojian Cheng Tongjin Lu Li Ren Chun Huang Xin

中国地质大学, 资源学院, 武汉, 430074 2. 中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

China University of Geosciences, Wuhan, Hubei 430074, China 2. Wuxi Research Institute of Petroleum Geology, Research Institute of Petroleum Exploration and Production, SINOPEC, Wuxi, Jiangsu 214151, China

烃类垂向微渗漏是油气化探的理论基础,在地表形成的化探异常形态和特征受油气分布、盖层、断裂与裂隙系统、储层流体属性等因素影响。为了研究油气藏中烃类垂向微渗漏近地表异常显示的主要受控因素,在苏北盆地盐城凹陷朱家墩气田上方近地表开展了以游离烃、顶空气法为主的地球化学勘探研究。结果显示,这些活跃的烃类指标异常分布与下伏气藏上方的优势运移通道具有良好的响应关系,表明油气藏中的烃类垂向微渗漏至地表是客观存在的事实。通过对已知气藏封盖条件和运移通道的分析,认为对该气田上方烃类垂向微渗漏的近地表异常显示起主控作用的是断层、盖层中的裂缝发育带和地层中的微裂缝系统。试验结果为今后研究油气藏上置化探异常模式及成因机理提供了较好的证据。

Hydrocarbon vertical microseepage is the theoretical foundation of surface geochemistry exploration.Surface geochemical anomalies are dominated by oil-and-gas distribution,cap rock,faults and fractures system as well as reservoir fluid property.In order to learn the dominating factors of surface expressions from hydrocarbon microseepage,surface geochemical explorations with free gas and headspace gas methods have been made over the Zhujiadun Gas Field,the Yancheng Sag,the northern Jiangsu Basin.It has been found out that,hydrocarbon index anomalies are in good response to favorable migration passages over gas fields,proving hydrocarbon vertical microseepage to surface.Analyzing sealing conditions and migration pathways of known gas accumulations,it has been concluded that fracture system in faults and cap rocks and microfracture system in strata are the controlling factors for near surface anomalies of hydrocarbon vertical microseepage.The results are good evidences for further studies of anomaly pattern and mechanism over oil and gas accumulations.

中国石油化工集团公司科技开发项目(P05069)

https://doi.org/10.11781/sysydz200803302