渤海南堡35-2油田原油物性差异地质成因分析  

Geological genetic analysis on the physical properties difference of crude oil in NB35-2oilfield,Bohai sea

作　　者：李浩 胡勇 别旭伟 潘广明 聂玲玲 LI Hao;HU Yong;BIE Xuwei;PAN Guangming;NIL Lingling(CNOOC China Limited,Tianjin Branch,Tianjin 300452, China)

机构地区：[1]中海石油(中国)有限公司天津分公司

出　　处：《中国海上油气》2019年第5期53-61,共9页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项课题“渤海油田加密调整及提高采收率油藏工程技术示范(编号:2016ZX05058-001-008)”部分研究成果

摘　　要：渤海南堡35-2油田各区原油物性平面差异较大。S-1区为轻质油油藏,油质最轻;南区为重质稠油油藏,地层原油黏度和密度从东南向西北逐渐增大;断块区地层原油黏度和密度介于南区和S-1区之间,油质由南向北逐渐变重。为明确原油物性差异的地质成因,以油气成藏理论和原油稠化机制为分析手段进行综合研究,认为该油田各区原油物性差异并非是不同油源造成的,并且烃源岩有机成熟度高,原始油品好,形成轻质油藏概率大;而稠油油藏是后期改造作用形成的,同一油源运移距离越远,受到生物降解、水洗等稠化作用越严重,原油密度和黏度容易增大。微生物降解受地层温度、断层活动速率和油水层空间位置关系控制:地层内部温度异常高,不易发生生物降解,原油密度和黏度越小;断层活动速率越低,地层原油黏度和密度越小;油水过渡带范围越大,生物降解程度越大,原油黏度和密度越大。同时,预测斜坡区原油黏度与密度和断块区南部相似,为该区优质储量潜力区。The physical properties of crude oil in different areas of NB35-2 oilfield in Bohai sea are quite different on the plane. The S-1 area is a light oil reservoir with the lightest oil gravity;the southern area is a heavy oil reservoir, and the in-situ crude oil viscosity and density increase gradually from the southeast to the northwest;the in-situ viscosity and density of crude oil in the fault block area are between that of the southern area and S-1 area, and the oil gravity gradually increases from south to north. In order to clarify the geological geneses of crude oil physical properties difference, a comprehensive study was carried out by means of hydrocarbons accumulation theory and crude oil thickening mechanism, and it was believed that the difference on crude oil physical properties of different areas was not caused by different oil sources. Moreover, the higher the maturity of organic matters in source rocks, the better the original oil quality will be, and the larger the probability of forming a light oil reservoir. The heavy oil reservoir was formed by the modification in the late period. The farther the migration distance of the same oil source is, the more serious the thickening effect of biodegradation and water washing, and the larger crude oil density and viscosity will be. Microbial degradation is controlled by formation temperature, fault activity rate and the spatial position of oil-water layer: The abnormally high internal temperature of formation hinders the biodegradation, and the density and viscosity of crude oil are smaller. The lower the activity rate of fault, the smaller the in-situ viscosity and density of crude oil;the larger the scope of transition zone, the greater the degree of biodegradation, and the larger the viscosity and density of crude oil will be. At the same time, it was predicted that the viscosity and density of crude oil in the slope area are similar to those in the southern part of the fault block, which is a potential area of high-quality reserves in this area.

关 键 词：南堡35-2油田 原油物性差异 地质成因 运移距离 地层温度 断层活动速率 油水过渡带 

分 类 号：TE122.1[石油与天然气工程—油气勘探]