Modeling of nanoparticle fluid microscopic plugging effect on horizontal and vertical wellbore of shale gas

Abstract Shale gas is an important part of realizing the modern multi-energy system as a kind of unconventional energy with huge reserves for human energy needs. Adding nanomaterials to plug shale pores is an effective method to improve shale gas development. However, the dynamic migration of nanoparticles in shale pores, the time-space process of plugging, and the mapping relationship between permeability under different wellbore conditions are unclear. In this paper, a fluid-solid coupling nano-blocking model based on pore characteristics, fluid physical properties, and discrete element parameters is established considering the nano-scale effects. In order to ensure the rationality of the nanoparticle force, codes were written to modify the flow resistance. Pore ratio with perpendicular and parallel to shale bedding and channel bending degree model is established, and their rationality is verified through experiments. Particle concentration, size, particle release mode and shape factors for plugging efficiency were discussed with different wellbore conditions. Results indicate the plugging gap between horizontal and vertical wells narrowed by 43.76% as particles increased from 1 wt% to 5 wt%. Increasing the particle size has a greater impact on plugging efficiency of vertical well pores. In the multi-scale particle release mode, the particle plugging effect is increased by 90.44% and 94.22% compared with vertical and horizontal wells, respectively. The research results can provide nano plugging solutions in drilling fluid for shale gas development.