非均质线性模型水驱油试验研究

EXPERIMENT STUDY ON HETEROGENEITY LINEAR MODEL OF WATER DRIVING OIL

为了确定岩心组合方式、渗流方式、渗透率的大小、非均质性等对驱油效率和剩余油分布的影响,首先选取不同的天然岩心,运用岩心组合技术,建立起不同的非均质模型;然后结合物理模拟技术,用恒速法进行水驱油试验。试验发现:平面非均质模型单向渗流时,剩余油饱和度和驱油效率与岩心渗透率无关,而与岩心所处位置密切相关,从模型的入口到出口,剩余油饱和度递增,驱油效率递减;低中高模型剩余油分布较均匀,而高中低模型剩余油集中分布在低渗透岩心;模型的驱油效率与其等效渗透率、非均质性相关;纵向非均质模型驱替后,剩余油主要分布于渗透率最低的岩心。研究认为:在平面非均质性比较严重的油层,可采取高渗区注水,低渗区采油,这样可以获得较高的采收率;在纵向非均质性比较严重的油层,可采用化学调剖堵水封堵高渗透层、改善吸水驱替剖面或者分层注水开采的方式来获得较高的采收率。

In order to determine the impact of different combined core mode,percolation matter,permeability,heterogeneity on water flooding efficiency and distribution of remaining oil,and to do further research,this dissertation firstly selects different natural cores,uses combined core technique,and establishes different heterogeneous models.Then with the help of combined physical simulation technique and constant flow rate method,water driving oil experiment is done.From the experiment,the following findings are acquired: as series connection model is one-way percolating,water flooding efficiency at inlet is obviously higher than that at outlet,saturation of remaining oil at outlet is obviously higher than that at inlet,and water flooding efficiency and saturation of remaining oil has nothing to do with the value of permeability;the distribution of remaining oil is even in the low-medium-high model,whereas it is centralized in the low permeability core in the high-medium-low model;the water flooding efficiency of the combined model has connection with the equivalent permeability and heterogeneity.As vertical heterogeneous model is water flooding,the remaining oil is centralized in the least permeability core.Finally,it is concluded that in the formation characterized by obvious horizontal heterogeneity character,the project of water flooding in high permeability zone and oil extraction at low permeability zone can be adopted to improve the recovery ratio. And in the formation characterized by obvious vertical heterogeneity character, the projects of chemical water plugging by profile control,plugging the high permeability formation,improving water entry profile,or separate water injection can be adopted to improve the recovery ratio.