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- Title
致密储层不同二氧化碳注入方式下的沥青质沉积特 征及其对渗透率的影响.
- Authors
杨明洋; 黄世军; 赵凤兰; 孙浩月; 陈新阳
- Abstract
The asphaltene deposition of crude oil caused by CO2 injection will damage the tight reservoir and seriously affect the ultimate recovery. In order to clarify the characteristics of asphaltene deposition and the influence on reservoir permeability under different CO2 injection methods, the experiments of CO2 flooding and CO2 huff-n-puff were carried out. The characteristics of asphaltene deposition, the performance of oil recovery, and the influences on the permeability of tight cores under different injection methods were analyzed by nuclear magnetic resonance (NMR) and scanning electron microscope (SEM). The results showed that the asphaltene deposition occurred in the tight cores under both of CO2 flooding and huff-n-puff, which was mainly deposited on the pore surface by membrane adsorption. Influenced by the interaction time between CO2 and crude oil, the amount of asphaltene deposition under CO2 huff-n-puff was greater than that under CO2 flooding. Moreover, the pore size range of asphaltene deposition under CO2 huff-n-puff was higher than that of CO2 flooding. The damage of asphaltene deposition to core permeability was related to the direction of crude oil production. Asphaltene deposition had greater damage to the forward (CO2 injection direction) core permeability under CO2 flooding, while that had greater damage to the reverse core permeability under CO2 huff-n-puff. When the confining pressure was 10 MPa and 5 MPa, the damage of asphaltene deposition under CO2 flooding and CO2 huff-n-puff to the forward core permeability (average decrease of forward permeability) was 7.05% and 1.67%, while the damage degree of the reverse core permeability (average decrease of reverse permeability) was 0.41% and 2.66%, respectively. Due to the influence of injection-production mode and flow mechanisms, the recovery of CO2 huff-n-puff was lower than that of CO2 flooding. The research results were significant in understanding the damage caused by asphaltene deposition in different directions and selecting injection methods during CO2 injection in tight oil reservoirs.
- Publication
Oilfield Chemistry, 2024, Vol 41, Issue 1, p85
- ISSN
1000-4092
- Publication type
Article
- DOI
10.19346/j.cnki.1000-4092.2024.01.012