孤岛油田东区馆6低含油饱和度特稠油油藏成藏条件及油水分布模式

Accumulation conditions and oil-water distribution patterns of low oil-saturated super-heavy oil reservoir in Ng6 layer in the east region of Gudao Oilfield

低含油饱和度特稠油油藏的油水关系一般较为复杂,针对该类油藏开展油水分布规律研究是可动用储量评价与开发的基础。应用测井、岩心分析及开发动态等资料对孤岛油田东区馆6开展储层含油性评价及油水分布特征研究,认为其为油水关系复杂的低含油饱和度特稠油油藏。其油气成藏机制为:以重力、浮力为主的弱成藏动力难以排驱较小喉道孔隙中的原生水,致使河道边缘、河间滩地等物性较差的砂体含油饱和度较低;油气成藏后,孤北断层剧烈活动,致使其附近区域的地面原油密度超过1.01g/cm^3,具有一定长度的连续油柱足以克服毛细管力排出孔隙,聚集于构造低部位,形成油水倒置现象。以油藏成因机制研究为指导,根据油水分布特征及控制因素,将孤岛油田东区馆6低含油饱和度特稠油油藏的油水分布模式划分为4种类型,分别为岩性控制的Ⅰ类、构造控制的Ⅱ类、构造和岩性双重控制的Ⅲ类、油水密度分异控制的Ⅳ类,并制定了差异化的开发策略,进而实现储量评价及有效动用。

The oil and water relationship of low oil-saturated super-heavy oil reservoir is generally complicated.In this kind of reservoir,the study of oil-water distribution rule is the basis for probable reserves evaluation and development.Based on the data of logging,core analysis and development performance,the evaluation of oil-bearing property of reservoir and the oil and water distribution characteristics were studied in Ng6 layer in the east region of Gudao Oilfield,and it is be.lieved that the reservoir is a low oil-saturated reservoir with complicated oil and water relationship.The weak driving forces dominated by gravity and buoyancy are difficult to drain the original water in pores with small throats,which leads to a low.er oil saturation of sand bodies in the river edge and river beach with poor physical property.After the accumulation of oiland gas,the intense movement of Gubei Fault make oil density increase to 1.01 g/cm^3,and continuous oil column with a certain length is able to make oil overcome capillarity pressure and blow out of pore to gather in low part of the structure and make inversion of oil and water.Directed by reservoir development mechanism based on oil-water distribution characteristics and control factors,the oil-water distribution pattern of Ng6 low oil-saturated super-heavy oil can be divided into four patterns including,lithological controlled patternⅠ,tectonic controlled patternⅡ,tectonic and lithological controlled patternⅢ,and oil-water density differentiation controlled patternⅣ.This research formulates the differentiated development strategy and realizes reserves evaluation and effective utilization.