Affiliation:
1. Research Institute of Exploration and Development, Xinjiang Oilfield Company, PetroChina, Karamay 834000, China
2. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China
Abstract
Conglomerate reservoirs are usually formed in sag slope belts, which have the characteristics of near-source rapid deposition, rapid sedimentary facies change, and distinct reservoir heterogeneity. Therefore, it is difficult to carry out treatments of stimulation because of insufficient understanding of the propagation mechanism of the unique “gravel-bypassing” and “gravel-penetrating” characteristics of fracture morphologies in Mahu conglomerate reservoirs. In order to study the law of hydraulic fracture propagation in conglomerate reservoirs, based on Brazilian splitting test results for conglomerates with different gravel particle sizes and different cementation degrees, true tri-axial fracturing experiments conducted in the laboratory were performed to conduct experimental research on natural conglomerate outcrops and analyze the effects of gravel size, fracturing fluid viscosity, and pumping rate on hydraulic fracture propagation morphology. The results show that: (1) the gravel cementation strength of fracture pressure is higher and the pressure drops preferably after fracturing. The fracture is more inclined to “pass through the gravel” to propagate in large-particle-size gravel. The poor gravel cementation of fracture pressure is relatively low-level and the pressure after fracture drops slightly, and fractures tend to occur at the margin of gravel; (2) using slick water for fracturing tends to initiate and propagate fractures at multiple points on the wellbore, which is conducive to the formation of complex fracture networks and the improvement of volume stimulation effects. Guanidine-gum fracturing has a higher fracture-forming efficiency and higher net pressure; and (3) a low pumping rate will increase the interaction degree between fractures and gravel, and gravels will cause a change in fracture roughness, resulting in small local fracture widths.
Subject
Process Chemistry and Technology,Chemical Engineering (miscellaneous),Bioengineering
Reference28 articles.
1. Channel architecture element and its controls on hydrocarbon accumulation: A case study from Chang-8 member in Huaqing area, Ordos basin;Xiao;Xinjiang Pet. Geol.,2018
2. Chen, X., Zhi, D., and Wang, X. (2018). Typical Reservoirs in Oil and Gas Fields of Junggar Basin: The Southern Margin, Petroleum Industry Press.
3. Geological features, major discoveries and unconventional petroleum geology in the global petroleum exploration;Zou;Pet. Explor. Dev.,2010
4. Yang, Y.-T. (2022). Evaluation of Petroleum Resources in Mahu Area, Junggar Basin. Guangzhou Chem. Ind., 50.
5. Pressure Analysis of Fractured Horizontal Wells Considering the Complex Modal Structure of Mahu Conglomerate Reservoir;Song;Sci. Technol. Eng.,2022