鄂尔多斯盆地中生界低压油藏特征与形成机制  

Characteristics and Formation Mechanism of Mesozoic Underpressured Reservoirs in Ordos Basin

作　　者：段毅[1] 曹喜喜 赵阳[1] 张忠义[2] 余永进 吴应忠[1] 徐丽[1] 何金先[1] 夏嘉[1] 张晓丽[1] 赵彦德[2] 齐亚林[2] 

机构地区：[1]中国科学院地质与地球物理研究所油气资源研究重点实验室,甘肃兰州730000 [2]中国石油长庆油田分公司勘探开发研究院,陕西西安710021 [3]中国石油长庆油田分公司第二采油厂,甘肃庆阳745000

出　　处：《地球科学（中国地质大学学报）》2014年第3期341-349,共9页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(No.41272125)

摘　　要：首次对鄂尔多斯盆地中生界油藏压力进行了研究，发现中生界油藏主要为超低压油藏，并且不同地区和不同层位油藏的异常低压差别显著．研究结果表明，随着地层剥蚀厚度增大和油藏抬升后温度降低值增加，储层压力系数呈减少趋势；延长组油藏抬升温度降低后使储层孔隙水的体积收缩量达0．82％～1．94％．这些指示了盆地在白垩纪末期长时间强烈抬升，地层剥蚀和古地温降低作用是形成低压油藏的主要原因．认为鄂尔多斯盆地中生界这种低压封闭体系对油藏的保存有利，同时对油藏调整、油气运移再富集和油水分布等成藏方面可能起到了重要作用．提出了陕北地区长6低压油藏由东南向西北方向富集和长7砂岩透镜体不含水低压油气藏形成，均与这种低压封闭体系分布密切相关．The pressure characteristics of Mesozoic oil reservoirs in Ordos Basin was studied for the first time. It is found that the Mesozoic oil reservoirs are mainly ultra-underpressured ones and the abnormal underpressure difference in oil reservoirs a- mong different regions and different layers is distinct. The results show that oil reservoir pressure coefficients exhibit a decrea- sing trend with the increase of eroded strata thickness and temperature drop value of oil reservoirs after, and the reservoir pore- water volume contraction amounts to 0. 82%--1.94 as a result of temperature drop after uplift of Yanchang Formation oil reservoirs, which indicates that the function of strata erosion and paleotemperature decrease due to long time and strong uplift of the basin at the end of the Cretaceous result in the formation of underpressured oil reservoirs. The underpressured closed system of Mesozoic in the Ordos Basin is believed to be advantageous for oil reservoir preservation and may have played an im- portant role in oil reservoir adjustment, re-enrichment of hydrocarbon by migration and oil and water distribution in oil reser- voirs. It is concluded that Chang-6 underpressured reservoir enriched from the southeast to the northwest in the North Shaanxi area and presence of Chang-7 lenticular sandstone body reservoirs with absence of water are closely related to the distribution of such underpressured closed systems.

关 键 词：低压油藏 形成机制 含油地层 透镜体 中生界 鄂尔多斯盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]