Acta Petrolei Sinica ›› 2020, Vol. 41 ›› Issue (7): 875-884,902.DOI: 10.7623/syxb202007009

• Oil Field Development • Previous Articles     Next Articles

Influence of CO2 flooding mode on oil displacement effect and reservoir damage in heterogeneous multi-layer reservoirs

Wang Qian1, Yang Shenglai1, Bai Jie2, Qian Kun1, Li Jiajun1   

  1. 1. College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China;(;
    2. Research Institute of Oil/Gas Technology, PetroChina Changqing Oilfield Company, Shaanxi Xi'an 710021, China
  • Received:2019-07-25 Revised:2020-04-27 Online:2020-07-25 Published:2020-08-08

非均质多层储层中CO2驱替方式对驱油效果及储层伤害的影响

王千1, 杨胜来1, 拜杰2, 钱坤1, 李佳峻1   

  1. 1. 中国石油大学(北京)石油工程学院 北京 102249;
    2. 中国石油长庆油田公司油气工艺研究院 陕西西安 710021
  • 通讯作者: 杨胜来,男,1961年10月生,1982年获太原理工大学学士学位,1996年获中国矿业大学博士学位,现为中国石油大学(北京)石油工程学院教授,主要从事油气田开发工程方向研究工作。Email:yangsl@cup.edu.cn
  • 作者简介:王千,男,1991年1月生,2014年获西南石油大学学士学位,现为中国石油大学(北京)博士研究生,主要从事油气田开发方向的研究。Email:wq5635137@163.com
  • 基金资助:

    国家自然科学基金项目"超深层碎屑岩油气藏渗流物理基础研究"(No.51774300)和国家科技重大专项"CO2驱油与埋存关键技术"(2016ZX05016-006-004)资助。

Abstract:

During the development of low-permeability reservoirs by CO2 injection, reservoir blockage caused by asphaltene precipitation and CO2-formation water-rock interaction exacerbates the complexity of displacement characteristics in heterogeneous multilayer sandstone reservoirs, thus affecting the seepage of fluids in reservoirs and final oil recovery during CO2 and CO2-WAG flooding. In this study, the CO2 and CO2-WAG flooding experiments were conducted in simulated multi-layer reservoir systems with similar physical properties under miscible conditions (70℃, 18 MPa). The two displacement modes were evaluated in terms of oil and gas production, remaining oil distribution and permeability damage. The experimental results show that the oil recovery of the entire system is lower after CO2 flooding, the oil production is mainly from the high permeability layer, the remaining oil is distributed in the medium and low-permeability layers. During the CO2-WAG flooding, the CO2 breakthrough time was late, and the oil recovery of the entire system was significantly improved. In addition, the permeability of the high-permeability layer decreased by 16.1% after CO2 flooding, and 95.1% of the decrease was caused by asphaltene precipitation. However, after CO2-WAG flooding, the permeability of each layer decreased by 29.4%, 16.8%, and 6.9%, respectively. Asphaltene precipitation is still the main factor and causes even more serious reservoir blockage. Moreover, the permeability decline caused by CO2-formation water-rock interaction in the high-permeability layer cannot be ignored, contributing 20.7% of the corresponding factors. Therefore, for multi-layer reservoirs with strong heterogeneity, CO2-WAG flooding has better oil displacement effect, but the prevention and control measures for asphaltene precipitation are necessary.

Key words: CO2 flooding, CO2-WAG flooding, remaining oil distribution, permeability reduction, asphaltene precipitation, CO2-formation water-rock interaction, multi-layer heterogeneous reservoir

摘要:

低渗透油藏注CO2开发过程中沥青质沉淀和CO2—地层水—岩石相互作用引起的储层堵塞加剧了非均质多层砂岩储层中驱替特征的复杂性,影响CO2和CO2-水交替驱(CO2-WAG)驱油过程中流体在储层中的渗流和最终的原油采收率。研究中的CO2和CO2-WAG驱油实验是在混相条件下(70℃、18 MPa)模拟的具有相似物性的多层储层系统中进行的,从油气产量、剩余油分布和渗透率损害3方面评价了两种驱替方式。实验结果表明,CO2驱后整个系统的采收率较低,产油主要来自高渗透层,剩余油分布在中、低渗透层。CO2-WAG驱过程中CO2突破时间较晚,整个系统的原油采收率显著改善。此外,CO2驱后高渗透层的渗透率下降了16.1%,95.1%的下降幅度是由沥青质沉淀引起。在CO2-WAG驱后,各层的渗透率下降幅度分别为29.4%、16.8%和6.9%,沥青质沉淀仍是主要因素,且引起的储层堵塞更严重,但高渗透层中CO2-地层水-岩石相互作用引起的渗透率下降不容忽视,占20.7%的因素。因此,对于具有强非均质性的多层储层,CO2-WAG具有更好的驱油效果,但是对沥青质沉淀的预防和控制措施是必要的。

关键词: CO2驱, CO2-WAG驱, 剩余油分布, 渗透率下降, 沥青质沉淀, CO2&mdash, 地层水&mdash, 岩石相互作用, 多层非均质储层

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