摘要：The reservoir type of the MH oil field in the Junggar Basin is a typical low-permeability conglomerate reservoir. The MH oilfield was developed by water injection in the early stage. Nowadays, the reservoir damage is serious, and water injection is difficult. There is an urgent need to carry out conversion injection flooding research to improve oil recovery. The use of CO2 oil-flooding technology can effectively supplement formation energy, reduce greenhouse gas emissions, and improve economic benefits. In order to clarify the feasibility of CO2 flooding to improve oil recovery in conglomerate reservoirs with low permeability, strong water sensitivity, and severe heterogeneity, this paper researched the impact of CO2 miscibility on production characteristics and mechanisms through multi-scale experiments. The aim was to determine the feasibility of using CO2 flooding to enhance oil recovery. This study initially elucidated the oil displacement characteristics of varying degrees of miscibility in different dimensions using slim tube experiments and long core experiments. Subsequently, mechanistic research was conducted, focusing on the produced oil components, changes in interfacial tension, and conditions for pore mobilization. The results indicate that the minimum miscibility pressure (MMP) of the block is 24 MPa. Under the slim tube scale, the increase in the degree of miscibility can effectively delay the gas breakthrough time; under the core scale, once the pressure reaches the near mixing phase, the drive state can transition from a non-mixed "closed-seal" to a "mixed-phase" state. Compared to the immiscible phase, the near-miscible and completely miscible phase can improve the final recovery efficiency by 9.27% and 18.72%. The component differences in the displacement products are mainly concentrated in the high-yield stage and gas breakthrough stage. During the high-yield stage, an increase in miscibility leads to a higher proportion of heavy components in the produced material. Conversely, in the gas breakthrough stage, extraction increases as the level of mixing increases, demonstrating the distinct extracting characteristics of different degrees of mixed phases. The core experiences significant variations in oil saturation mostly during the pre-gas stage. CO2 miscible flooding can effectively utilize crude oil in tiny and medium-sized pores during the middle stage of flooding, hence reducing the minimum threshold for pore utilization to 0.3 mu m.

关键字：conglomerate reservoir; MMP; near-miscible flooding; on-line NMR; composition change

ISSN号：2227-9717

卷、期、页：卷: 12期: 6

发表日期：2024-06-01

影响因子：0.000000

期刊分区（SCI为中科院分区）：四区

收录情况：SCI（科学引文索引印刷版）,地学领域高质量科技期刊分级目录（国外T2）,EI（工程索引）,SCIE（科学引文索引网络版）

发表期刊名称：PROCESSES

参与作者：寇根,肖志朋

通讯作者：罗贇,张一琦,赵帅,赵向上,白雷

第一作者：杨胜来,章星,陈浩,王秀宇

论文类型：期刊论文

论文概要：罗贇,杨胜来,张一琦,寇根,赵帅,赵向上,章星,陈浩,王秀宇,肖志朋,白雷，Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations，PROCESSES，2024，卷: 12期: 6

论文题目：Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations