Experimental study on the fracture closure law of fault-controlled reservoir

• Published in: Energy reports 2022-11, Vol.8, p.14428-14441
• Main Author: Liu, Hailong
• Format: Article
• Language: English
• Subjects: Closure law; Filling style; Fracture width; Permeability; Pressurization and depressurization
• ISSN: 2352-4847; 2352-4847
• DOI: 10.1016/j.egyr.2022.10.376

This paper presents the fracture closure law of fault-controlled reservoir under different pressures by means of a combination of laboratory tests and numerical calculation. Fractures are an important seepage channel for fault-controlled reservoirs. With the improvement of the recovery degree of fault-controlled oil and gas reservoirs, the formation pressure decreases, and the effective rock stress increases, which leads to the deformation and even closure of fractures. The dynamic opening and closure of fractures restricts the formation permeability and affects the production of oil and gas wells. In this paper, experimental methods are used to study the fracture closure law. First collect carbonate rock samples, prepare samples through Brazilian splitting experiment and linear cutting method. We establish fracture deformation analysis method based on CT scan gray image. Through pressurization and depressurization test, the closure law of fractures under different filling conditions and fracture extension length was studied. The research results show that as the confining pressure increases, the fracture width and permeability gradually decrease. The stronger the ductility of the filler is, the more obvious the fracture closure is under pressure, and the greater the permeability reduction is. For the same quartz filled fractures, fracture closure laws are different under different filling methods. For fracture support effect, the single layer fine sand > thick layer fine sand > medium-fine mixture sand. In general, the greater the fracture extension length, the higher the permeability, but the increase of permeability is different. The findings of this study can help for a better understanding of reasons for large differences in single well productivity and contribute to rational productivity optimization of fault-controlled reservoirs.