Mesoscale modeling on the influence of surfactants on seepage law during water injection in coal--颗粒学报PARTICUOLOGY

a College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China
b State Key Laboratory of Mining Disaster Prevention and Control Co-Founded By Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China
c Sinopec Research Institute of Safety Engineering Co., Ltd., Qingdao, 266000, China
d State Key Laboratory of Safety and Control for Chemicals, SINOPEC Research Institute of Safety Engineering Co., Ltd., Qingdao, 266000, China
e College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, 266590, China

10.1016/j.partic.2024.10.014

Volume 96, January 2025, Pages 1-13

Received 26 September 2024, Revised 22 October 2024, Accepted 23 October 2024, Available online 2 November 2024, Version of Record 12 November 2024.

E-mail: zhcj.qday@sinopec.com

Highlights

• Microscale digital cores of coal treated by CAB, CDEA, and SDS were reconstructed.

• With the water flow, average velocity exhibited the rapid, slow, and steady decline.

• Critical values of pressure difference within surfactants spread out were determined.

• When ΔP surpassed 15.6 MPa, water injection effect of CDEA-treated coal began improve.

Abstract

To investigate the mesoscopic influence of surfactants on seepage law during water injection in coal seam, this paper innovatively establishes a fluid transport lattice Boltzmann (LBM) model by incorporating the seepage resistance generated from the porous media and external forces, which embodies the impact of wettability degree resulted from cocamidopropyl betaine (CAB), sodium dodecyl sulfate (SDS), and coconutt diethanol amide (CDEA) reagents at a 0.1% concentration. The main conclusions derived from this investigation are as follows: Firstly, as the lattice number in the X direction increases, the average seepage velocities in coal samples treated by deionized water, 0.1% CAB, 0.1% SDS, and 0.1% CDEA reagents (Nos. 1, 2, 3, and 4) exhibit three distinct stages: rapid decline, slow decline, and steady decline; in comparison to raw coal sample, modified coal samples demonstrate decreases of 20.84%, 33.91%, and 61.70%, respectively. Secondly, the critical values of displacement pressure difference exist during the phenomenon that modified reagents spread out in the entire flow channel, which are 3.5, 3.5, and 5.2 MPa, respectively, for coal samples Nos. 2, 3, and 4; this signifies that surpassing these critical values help prevent issues such as blank belts within the wetting range and insufficient dust control. Finally, at a displacement pressure difference of 0.01 (lattice unit), the average velocity ratios for samples (Nos. 2, 3, and 4) are 0.78, 0.56, and 0.37 (lattice unit), respectively; notably, the water flow velocities in modified coal samples are lower compared to that in raw coal sample, indicating that the addition of surfactants impede the seepage process of water injection in coal seam. Moreover, when the displacement pressure difference reaches 0.03 (lattice unit), the velocity ratio of CDEA-modified coal sample exceeds 100%; this means that when the displacement pressure difference surpasses 15.6 MPa, the water injection effect of CDEA-modified coal sample begins to be improved. These research findings offer a theoretical basis for enhancing water injection technology in coal mines.

Graphical abstract

Keywords

Mesoscale seepageSurfactantLattice Boltzmann methodVelocity ratioCritical displacement pressure difference

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