渤海油田非连续化学驱提高采收率机理  

Mechanism of enhanced oil recovery by discontinuous chemical flooding in Bohai oilfield

作　　者：张健 李宜强[3] 李先杰 管错 陈鑫 梁丹 Zhang Jian;Li Yiqiang;Li Xianjie;Guan Cuo;Chen Xin;Liang Dan(State Key Laboratory of Offshore Oil and Gas Exploitation,Beijing 102209,China;CNOOC Research Institute Co.,Ltd.,Beijing 100028,China;College of Petroleum Engineering,China University of Petroleum,Beijing 102249,China)

机构地区：[1]海洋油气高效开发全国重点实验室,北京102209 [2]中海油研究总院有限责任公司,北京100028 [3]中国石油大学(北京)石油工程学院,北京102249

出　　处：《石油学报》2024年第6期988-998,共11页Acta Petrolei Sinica

基　　金：中海石油(中国)有限公司科技项目(KJGG2021-05)资助。

摘　　要：渤海水驱油田以高孔高渗疏松砂岩为主,分大段强注强采至高含水阶段非均质性进一步加剧,存在水驱及常规聚合物驱方式难以动用更多小层、持续有效扩大波及等问题。按照化学体系调驱强度的差异,分别将凝胶、弹性分散流体和聚合物定义为强、中、弱3级调驱体系。根据连续化学驱(持续注入单一段塞体系)过程中渗流阻力动态变化规律,结合非均质岩心有效注入压力测试研究由强、中、弱3种调驱体系组合而成的非连续化学驱(DCF)扩大波及体积的动态特征;基于微流控实验揭示其扩大波及体积的微观机理,利用并联岩心驱替实验优化了DCF段塞组合注入方式;最后通过海上油田矿场试验验证DCF提高采收率的可行性。研究结果表明,连续化学驱过程中油水两相总流度持续增加,非均质岩心中的高渗区域总流度占比增大,扩大波及体积能力受限,不同药剂体系段塞组合的DCF驱替模式可以有效解决单一段塞增阻能力不足、过强或不均匀的问题;微流控实验表明,强-弱组合和弱-强组合DCF可较连续注入单一体系分别扩大波及29.2%和14.0%;岩心驱替实验表明,中-强-弱-强-弱DCF组合方式效果较好,可以在连续聚合物驱基础上提高采收率4.41%。有效调控注采压差和持续扩大微观波及体积是非连续化学驱提高采收率的主要机理。DCF模式在渤海BZ油田2口井的先导试验受效井含水率最大降低14%,增油量为6.97×10^(4)t,控水增油效果良好。The water-flooding oilfield in Bohai Bay is dominated by the unconsolidated sandstone with high porosity and high permea-bility.As a result,the heterogeneity is further intensified from the stage of strong injection and production in long subsection to the high water cut stage.This leads to a series of problems,such as the difficulty in exploiting more sub-layers by water flooding and conventional polymer flooding and continuously and effectively expanding the swept volume.According to the differences in flooding control strength in chemical system,polymer gel,elastic dispersion fluid and polymer were defined as being of strong,medium and weak flooding control system.Based on the dynamic change rules of flow resistance during continuous chemical flooding(continuous injection in a single slug system),in combination with a test on the effective injection pressure of heterogeneous cores,a study was performed on the dynamic characteristics of expanding the swept volume by discontinuous chemical flooding(hereinafter referred to as DCF),composed of strong,medium,and weak flooding control systems.Then,the microscopic mechanism of the expanded swept volume was revealed by microfluidic experiment.The discontinuous chemical flooding slug combined injection mode was opti-mized by the parallel-cores flooding experiment.Finally,the feasibility of enhanced oil recovery by discontinuous chemical flooding was verified by field tests in offshore oilfields.The results show that the total mobility of oil and water phases during the continuous chemical flooding process is increased,the proportion of the total mobility of the high-permeability area in heterogeneous core is also increased,and the ability of expanding swept volume is restricted.Therefore,DCF substitution model for the slug combinations of different pharmaceutical systems can be used to effectively solve the problem of insufficient,excessive or uneven resistance increasing capacity from single slug injection.In addition,microfluidic experiments show that the"strong-weak

关 键 词：渗流阻力 非连续化学驱 波及体积 注采压差 段塞组合 

分 类 号：TE357[石油与天然气工程—油气田开发工程]