陕北中生界特低渗透高含水油藏特征及成因

结合油田开发实际，通过对试油试采等资料的综合整理与分析，总结陕北魏家楼油田长6特低渗透高含水油藏的基本特征及其高含水区带的分布规律，并探讨了其成因。研究结果表明，魏家楼油田长6油藏属于典型的特低渗透高含水油藏，含水率等值线在平面上围绕局部构造高点呈不规则的环带状分布；油藏内部含水率分布具强非均质性，沿北东—南西方向上含水率变化相对稳定，等值线呈带状延伸；沿北西—南东方向上含水率起伏较大，等值线呈现高、低含水区带交替相间分布；局部夹有高含水带的异常突入。资源条件差、油源不足是魏家楼油田长6特低渗透油藏高含水的根本原因；原油黏度高、流体性质差异大、流度比高、天然裂缝发育是其高含水的主要内因。图5表2参12

Characteristics and causes of Mesozoic reservoirs with extra-low permeability and high water cut in northern Shaanxi

Combining with actual oil field development, based on comprehensive analysis on the oil production and oil test data, this paper summarizes the characteristics of the Chang 6 reservoir of extra-low permeability and high water?cut?in the Weijialou oilfield in northern Shaanxi and the distribution rule of high water cut zones. The results show that the Chang 6 reservoir in the Weijialou oilfield belongs to a typical reservoir with extra-low permeability and high water cut, its water cut contour shows irregular annular distribution around local structure highs in plane. The water cut distribution within the reservoir shows high heterogeneity; along the NE-SW direction, water cut change was relatively stable, water cut contour extending in band shape; along the NW-SE direction, water cut fluctuated greatly, contours showing an alternating distribution of high and low water cut zones; there exists high water cut zone out-thrusting locally. Lack of effective hydrocarbon source rocks and poor resources conditions are the underlying causes of high water cut in the Chang 6 extra-low permeability reservoir in the Weijialou oilfield. High crude oil viscosity, large difference of fluid properties, high fluidity ratio, and well developed natural fractures are the main internal cause of high water cut.