三维大尺度非均质油藏模型下的剩余油水驱物理模拟实验研究

Water driving physical simulation test of remaining oil based on 3D large-scale heterogeneous reservoir model

为弄清绥中36-1油田在中高含水期剩余油分布的复杂情况,从高温高压实验上研究复杂非均质储层9点井网流场变化特征,基于新研制的三维大尺度岩心模型制作技术和油水饱和度立体采集系统,设计并开展了9点基础井网及加密后的排状注采井网流场特征研究的物理模拟实验。研究结果表明:对韵律复杂的注采井网来讲,剩余油分布也非常复杂、但存在一定的规律;对单一正韵律条件,即使在实验模型条件下注入水下沉也较为明显,剩余油主要分布在正韵律上部;在反韵律条件下注入水能够均匀波及模型各个渗透率层,剩余油主要集中在水动力弱的区域;在结构复杂的复合韵律情况下,剩余油的分布取决于复合结构中水驱作用弱的低渗透带,并不一定是边角井之间无流线穿过区域。同时,基于上述特征,还发现9点基础井网的水驱动用程度较高、可采出绝大部分可采储量、转为排状注采井网对非均质油藏可提高采收率的幅度为8%~10%,实验研究认为这种复杂韵律结构的储层从9点注采井网到排状注采井网加密的最大采收率难以逾越40%。

In order to find out the complex situation of remaining oil distribution at the middle and high water-cut stage of Suizhong 36-1 Oilfield,and by the study of the flow field variation characteristics of nine-point well pattern for complex heterogeneous reservoirs by high temperature and high pressure experiments,the physical simulation experiments for the nine-point well pattern and the characteristics research for flow field of infilled row shape injection-production well pattern were designed and carried out based on the newly developed 3D large-scale core modeling technology and the stereoscopic acquisition system for oil-water saturation.For the injection and production patterns with complex rhythms,the distribution of remaining oil was also very complicated,but there were certain rules:under the condition of single positive rhythm,the subsidence of injected water was obvious even in the experiments,and the remaining oil was mainly distributed in the upper part of the positive rhythm;under the condition of inverse rhythm,the injected water could spread evenly to all permeability layers of the model,and the remaining oil was mainly accumulated in the weak hydrodynamic area;under the condition of complex compound rhythm,the distribution of remaining oil depended on the low permeability zone with weak water flooding in the complex structure,and it was not necessarily the area without streamline between corner wells.At the same time,based on the above characteristics,it was found that the water flooding degree of nine-point well pattern was high,most recoverable reserves could be produced.And when nine-point well pattern transformed into row injection-production well pattern,the recovery rate of heterogeneous reservoir could be improved by about 8%~10%.Experimental studies suggest that no matter for the nine point injection production well pattern or the converted row shape injection-production well pattern,the maximum recovery rate of structure reservoirs with complex rhythmic was difficult to exceed 40%.