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为探索地表放射性异常与地下油气藏的关系,在4种类型的9个油气藏上收集了310口井的放射性测井数据,同时在5个油气藏上补充进行了地面放射性测量工作。测量结果表明,放射性异常从油层到地表具有延续性;在同一油层上方异常随测点与油层距离加大而减弱;复合式油气藏各油层异常独立存在;不同类型油藏异常总体形态相似,异常幅值与油藏圈闭条件有关;地表放射性异常形态和幅度受油藏埋深影响不大,但与油藏规模有一定关系。这些为油气物质垂直运移及放射性异常深部形成机制提供了直接证据。在此基础上,综合前人研究成果,提出了油田放射性物质来源主要是生油岩的观点和油气盆地内流体微运移循环的设想,建立了放射性异常综合成因模式,即:放射性物质伴随油气运移,在重力分异作用下,聚集在油藏周围水中;由于盖层对油水的排替压力不同,形成有利于水穿过盖层的条件;放射性物质与水一起在流体微运移循环作用下,沿微裂隙和孔隙运移到地表,形成油田边界高值放射性异常;油藏顶部地表放射性值的高低受氧化还原条件、潜水面深度和其他地表因素控制。
In order to explore the relationship between surface radioactive anomalies and subsurface reservoirs, radioactive logging data of 310 wells were collected on four types of nine reservoirs, while ground-based radiometric measurements were supplemented on five reservoirs. The results show that the radioactive anomalies have continuity from the reservoir to the surface; the anomalies above the same oil layer weaken with the distance from the reservoir to the reservoir; the reservoirs of the composite reservoirs are anomalously independent; the general anomalies of the different types of reservoirs are similar The amplitude is related to reservoir confinement conditions. The shape and amplitude of the radioactive anomalies on the earth surface are not significantly affected by the depth of the reservoir but have a certain relationship with the reservoir size. These provide direct evidence for the vertical migration of oil and gas and the deep formation of abnormal radioactivity. On the basis of this, based on previous research results, the author put forward the idea that the source of radioactive material in oilfield is mainly oil-derived rock and the idea of microcirculation of fluid migration in oil-gas basin. The synthetic pattern of radioactive anomalies is established, that is, radioactive material accompanies oil and gas Migration, gravitational differentiation, gathered in the water around the reservoir; due to the cover of oil and water displacement pressure is different, forming a favorable conditions for water through the cap layer; radioactive material and water in the micro-migration cycle The micro-fissures and pores migrate to the surface to form high-value radioactive anomalies along the oilfield boundary. The radioactivity at the top of the reservoir is controlled by redox conditions, depth of submerged surface and other surface factors.