砾岩油藏水驱与聚合物驱微观渗流机理差异

发布时间：2018-08-30 17:34

【摘要】：砾岩油藏特殊的沉积环境导致储层孔隙结构呈现复模态特征,渗流系统以"稀网-非网状"流态为主,水驱与聚合物驱微观渗流机理及两者差异的研究成为油藏提高采收率的难点和关键。克拉玛依油田属于典型的砾岩油藏,选取实际岩心为研究对象,采用CT扫描技术研究了亲水和弱亲油岩石的水驱和聚合物驱微观驱替机理,并且在驱油效率影响因素分析的基础上,建立了2种驱替方式下砾岩油藏的最终采收率计算模型。实验结果表明:砾岩油藏亲水岩石水驱与聚合物驱渗流机理均以沿岩石表面"爬行"驱替为主,而弱亲油岩石则均以沿孔隙中部"突进"驱替为主,由于渗流机理的差异性,亲水岩石水驱后残余油主要在细喉道及孔隙交汇处赋存,聚合物溶液通过更强的剪切拖拽作用把这些残余油切割成许多小油滴,进而随着聚合物溶液顺利通过狭窄的喉道向前运动,以达到提高油藏采收率的目的;弱亲油岩石水驱后残余油主要以油膜形态及细孔道赋存为主,聚合物溶液以更强的剪切应力促使油膜通过桥接连通和形成油丝2种方式从颗粒表面被聚合物驱替带走。由于聚合物溶液与注入水溶液的性质存在本质差别,导致复模态的孔隙结构对聚合物溶液渗流和驱替的影响远小于水驱溶液。因此,针对2种不同润湿性的岩石,储层孔隙结构是水驱油效率的主控因素,物性和含油性的影响较小,而聚合物驱效果则与水驱后残余油饱和度具有较好的相关性,利用建立的模型可以有效地预测2个驱替阶段油藏的采收率。
[Abstract]:Due to the special sedimentary environment of conglomerate reservoir, the pore structure of the reservoir presents complex modal characteristics, and the percolation system is dominated by "thin-network-non-reticular" flow state. The study of microscopic seepage mechanism and their differences between water flooding and polymer flooding has become the difficulty and key to improve oil recovery. Karamay oilfield is a typical conglomerate reservoir. The microcosmic displacement mechanism of hydrophilic and weakly oil-lipophilic rocks is studied by CT scanning technique. Based on the analysis of the influencing factors of oil displacement efficiency, the final recovery calculation model of conglomerate reservoir under two displacement modes is established. The experimental results show that the mechanism of hydrophilic rock flooding and polymer flooding in conglomerate reservoir is mainly "crawling" displacement along the rock surface, while the weak oil-lipophilic rock is mainly "protruded" displacement along the middle of the pore, due to the difference of seepage mechanism. After hydrophilic rock flooding, the residual oil mainly exists in the fine throat and pore interface, and the polymer solution cuts the residual oil into a lot of small oil droplets through a stronger shearing and dragging effect. Furthermore, with the polymer solution moving forward through the narrow throat to improve the oil recovery, the residual oil after water flooding of weakly oil-lipophilic rock is mainly oil film shape and fine pore formation. The polymer solution is driven by polymer displacement from the particle surface by bridging the oil film and forming the oil wire by means of stronger shear stress. Due to the essential difference between polymer solution and injected aqueous solution, the effect of complex mode pore structure on percolation and displacement of polymer solution is much smaller than that of water flooding solution. Therefore, for two kinds of different wettability rocks, the pore structure of reservoir is the main controlling factor of water flooding efficiency, the influence of physical property and oil content is small, while the effect of polymer flooding has good correlation with residual oil saturation after water flooding. The established model can effectively predict the oil recovery of two oil reservoirs in displacement stage.
【作者单位】：中国科学院大学地球科学学院;中国科学院计算地球动力学重点实验室;中国石油新疆油田公司勘探开发研究院;
【基金】：中国科学院大学校部青年教师科研启动基金项目(55103BY00) 中国石油天然气集团公司重大科技专项(2011B-1104)资助
【分类号】：TE312

【相似文献】