基于测井响应特征的烃源岩古超压成因分析——以鄂尔多斯盆地三叠系延长组7段烃源岩为例  

Origin analysis of paleo-overpressure of source rock based on logging response characteristics:Case study of the source rocks in the 7th member of Yanchang Formation of Triassic,Ordos Basin,China

作　　者：徐泽阳 刘震[1,2] 赵靖舟[3,4] 党佳城 李军 唐子怡[3,4] XU Zeyang;LIU Zhen;ZHAO Jingzhou;DANG Jiacheng;LI Jun;TANG Ziyi(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Provincial Key Lab of Hydrocarbon Accumulation Geology,Xi’an Shiyou University,Xi’an 710065,China;College of Earth Sciences&Engineering,Xi’an Shiyou University,Xi’an 710065,China;Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay 834000,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249 [3]西安石油大学/陕西省油气成藏地质学重点实验室,陕西西安710065 [4]西安石油大学地球科学与工程学院,陕西西安710065 [5]中国石油新疆油田分公司勘探开发研究院,新疆克拉玛依834000

出　　处：《天然气地球科学》2023年第11期1950-1960,共11页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:41502132)资助.

摘　　要：成藏期古压力对油气分布具有重要影响,但对其识别及成因分析的难度也远高于现今压力。为探讨鄂尔多斯盆地长7段是否存在古超压及其测井响应机制,提出了一套有机质含量影响的定量分析模型。通过经典超压成因判识模板反演分析与盆地模拟正演分析相结合,讨论了研究区长7段古超压成因及其成藏意义。结果显示:长7段高有机质含量对测井参数具有显著影响,定量分析认为由有机质引起的声波时差增量及密度减量分别在2.56~169.78μs/m和0.01~0.61 g/cm^(3)之间。以去除有机质贡献的声波时差和密度资料为依据,利用计算孔隙度对比法以及声波—密度交会图法进行分析,认为长7段存在过古超压,且生烃导致的流体膨胀增压是成藏期超压的主要来源。结合盆地模拟,指出生烃增压在时间上与烃源岩热演化匹配,在空间上与油藏分布吻合,进一步佐证了生烃增压成因的认识。认为古压力是重要的成藏主控因素之一,烃类聚集分布于高剩余压力区域中的局部低剩余压力区。The paleo-pressure during the accumulation period exerts a significant influence on the distribution of oil and gas,yet its origin is considerably more challenging to identify and analyze compared to present pressure.In this paper,a quantitative analysis model was proposed to investigate the existence of paleo-overpressure in the 7th member of Yanchang Formation(Chang 7 Member)of Ordos Basin and its logging response mechanism,with a focus on the influence of organic matter content.The origin of paleo-overpressure and its significance in hydrocarbon accumulation within the Chang 7 Member of the study area were discussed by employing the inversion analysis based on the classical origin identification template and the forward analysis based on the basin modeling.The findings indicate that the abundant organic matter content in Chang 7 Member exerts a significant influence on logging parameters.The quantitative analysis reveals that the increment of acoustic time difference and the reduction of density induced by organic matter are 2.56-169.78μs/m and 0.01-0.61 g/cm^(3),respectively.Based on the data of acoustic time difference and density with the removal of the contribution of organic matter,and used the methods of calculated porosity contrast and sonic velocity-density crossplot,it was concluded that there is paleo-overpressure in Chang 7 Member,and the fluid expansion and pressurization caused by hydrocarbon generation is the main origin of overpressure during the accumulation period.Combined with basin modeling,it was pointed out that the overpressure due to hydrocarbon generation matches the thermal evolution of source rock in time and hydrocarbon distribution in space,which further supports the understanding that the overpressure results from the fluid expansion by hydrocarbon generation.It was considered that paleo-pressure is one of the important controlling factors of reservoir formation,and hydrocarbon accumulation is distributed in the local low excess pressure area in the high excess pressure area.

关 键 词：古超压 超压成因 生烃增压 古压力恢复 

分 类 号：TE122.2[石油与天然气工程—油气勘探]