基于微观孔喉结构的剩余油形成机理与动用界限研究  

Formation Mechanism and Flow Limits of Residual Oil Based on Microscopic Pore Throat Structure

作　　者：李廷礼 郑文乾 耿志刚 李俊飞 吴婷婷 LI Ting-li;ZHENG Wen-qian;GENG Zhi-gang;LI Jun-fei;WU Ting-ting(CNOOC(China)Co.,Ltd.,Tianjin Branch,Tianjin 300452,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300452

出　　处：《科学技术与工程》2023年第30期12892-12899,共8页Science Technology and Engineering

基　　金：“十三五”国家科技重大专项(2016ZX05058001)。

摘　　要：根据剩余油形成机理与动用界限提出相应开发策略,对改善高含水期开发效果具有重要意义。首先,利用岩心驱替实验与T2谱相结合方法,分析了高倍数驱替下剩余油在不同孔喉半径中的分布规律;然后建立大、小孔喉微观并联模型,应用伯肃叶流动方程,揭示了原油在小孔喉中的滞留机理及临界驱替压力梯度;最后将大、小孔喉转化成油藏尺度下的高、低渗流层,考虑启动压力梯度,采用迭代法确定了滞留剩余油动用技术界限。结果表明,随着驱替倍数的增加,半径大于50μm大孔喉中的原油不断驱出,水相逐渐变为连续相,明显干扰半径10~50μm小孔喉中的原油流动,从而小孔喉形成“注水绕流式”滞留剩余油;此时小孔喉平均半径为35μm,对应的临界驱替压力梯度为0.06 MPa/m;确定剩余油有效动用技术界限,随着驱替压力梯度增大,驱油效率增加速度先加快后变缓。渤海SZ油田高含水期采取水平井联合定向井分层系开发模式,驱替压力梯度提高1.8倍,采油速度提高0.8个百分点,水驱采收率提高16.8个百分点,极大改善开发效果,进一步发展和丰富陆相稠油油田高效开发理论。It is of great significance to propose corresponding development strategies based on the formation mechanism and utilization limits of remaining oil,in order to improve the development effect during the high water cut period.Firstly,the distribution pattern of remaining oil in different pore throat radii under high magnification displacement was analyzed using a combination of core displacement experiments and T2 spectroscopy.Then,a micro parallel model of large and small pore throats was established,and the Bernoulli flow equation was applied to reveal the retention mechanism of crude oil in small pore throats and the critical displacement pressure gradient.Finally,the large and small pore throats were transformed into high and low permeability layers at the reservoir scale,considering the starting pressure gradient,and the iterative method was used to determine the technical boundaries for producing residual oil.The results indicate that as the displacement ratio increases,the radius is greater than 50 μm The crude oil in the m large pore throat is continuously expelled,and the water phase gradually becomes a continuous phase,with a significant interference radius of 10~50 μm.The crude oil in the small pore throat flows,resulting in the formation of a “water injection bypass flow” to retain remaining oil.At this point,the average radius of the small pore throat is 35 μm.The corresponding critical displacement pressure gradient is 0.06 MPa/m.Determine the technical boundary for effective utilization of remaining oil.As the displacement pressure gradient increases,the rate of increase in displacement efficiency first accelerates and then slows down.During the high water cut period of Bohai SZ Oilfield,a horizontal well combined directional well layered development model was adopted.The displacement pressure gradient increased by 1.8 times,the oil recovery rate increased by 0.8 percentage points,and the water drive recovery rate increased by 16.8 percentage points,greatly improving the development effect an

关 键 词：剩余油 高含水 孔喉半径 驱油效率 压力梯度 

分 类 号：TE341[石油与天然气工程—油气田开发工程]