Multiscale pore-fracture hybrid pore network modeling for drainage in tight carbonate. (April 2023)

• Record Type: Journal Article
• Authors: Xu, Zhipeng; Lin, Mian; Ji, Lili; Jiang, Wenbin; Cao, Gaohui; Xu, Leige
• Is Part Of: Advances in water resources. Volume 174(2023)
• Publication Date: 2023-04
• Subjects: Multiscale pores -- Fractures -- Multiscale hybrid pore network modeling -- Two-phase flow -- Tight carbonate; Hydrology -- Periodicals; Hydrodynamics -- Periodicals; Hydraulic engineering -- Periodicals; 551.48
• DOI: 10.1016/j.advwatres.2023.104420
• Languages: English
• ISSNs: 0309-1708

Abstract

Highlights: A multiscale pore-fracture hybrid pore network method for drainage in tight carbonate is proposed. Various void spaces at multiple length scales and the flow characteristics in them are considered. The construction parameters are studied to obtain robust network. The significance of incorporating fractures and micropores in drainage model is indicated. The generated multiscale pore-fracture hybrid pore network reproduces realistic transport properties. Abstract: Tight carbonate possesses both fractures and multiscale pores. Flow through tight carbonate rocks involves several length scales and the complicated flow physics. Capturing and modeling the entire void space into a single pore network model for drainage is challenging. Here, we present a novel method for modeling of a multiscale pore-fracture hybrid pore network, which enables various void spaces at multiple length scales and the flow characteristics in them to be included. Pores and fractures in a low-resolution CT image are extracted by medial axis-maximal ball algorithm and medial surface algorithm, respectively, to generate a pore-fracture hybrid pore network. Then, a statistics-based small-scale stochastic pore network is established in the CT image solid domains to represent the micropores unresolved by the image. The two pore networks are organically integrated into a multiscale hybrid pore network by cross-scale connections. The statistics of small-scale pore network are determined by experimental permeability. We study the effects of the small-scale pore network density on connectivity, single- and two-phase flow properties of the model to obtain the robust parameter. The influence of fractures on two-phase flow properties is analyzed. Results show the significance of incorporating fractures and micropores in the model. The model is validated via comparison between simulation result and experimental data. This method can accurately, efficiently, conveniently construct multiscale pore-fracture hybrid pore network of tight carbonate rock for evaluating the drainage characteristics.