Geological Control of Irreducible Water Within the Coal Matrix and Its Quantified Evaluation Model

Mingjun Zou; Yuanzheng Liu; Zhiquan Huang; Miao Zhang; Peilun Zhang

doi:10.1021/acsomega.0c00782

Geological Control of Irreducible Water Within the Coal Matrix and Its Quantified Evaluation Model

ACS Omega. 2020 Apr 13;5(16):9540-9549. doi: 10.1021/acsomega.0c00782. eCollection 2020 Apr 28.

Authors

Mingjun Zou¹, Yuanzheng Liu¹, Zhiquan Huang¹, Miao Zhang², Peilun Zhang³

Affiliations

¹ College of Geosciences and Engineering, North China University of Water Resources and Electric Power, Jinshui East Road No. 136, 450045 Zhengzhou, China.
² He'nan Province Research Institute of Coal Geological Prospecting, He'nan Coalfield Geological Bureau, Shangding Road No. 70, 450052 Zhengzhou, China.
³ Educational Administration Office, Shangqiu University, Beihai East Road No. 66, 476000 Shangqiu, China.

Abstract

This paper adopts the measurement of mercury intrusion porosimetry and nuclear magnetic resonance (NMR) to analyze the pore system and the pore structure of coal samples, and the measurement of maceral group composition, scanning electron microscopy, and energy dispersive X-ray spectroscopy to obtain the organic/inorganic composition of coal samples. Gravimetric and NMR methods are both used to calculate irreducible water saturation of the samples, and qualitative and quantitative research studies are therefore conducted. The following knowledge is obtained. Coal samples can be classified as micro-trans-pore-dominated samples, meso-macro-pore-dominated samples, cleat-dominated samples, and even development samples. The main composition of the samples is organic, and a little kaolinite and pyrite can be observed. Irreducible water saturation obtained by the gravimetric method is almost close to that gained by the NMR method. The influencing parameters can be divided into two categories. The first category contains the maximum vitrinite reflectance, volumetric factor, fixed carbon yield, volatile yield, vitrinite percentage, and inertinite percentage, which have a strong correlation with irreducible water saturation. The second category includes the buried depth and median radius, and they have a weak correlation with irreducible water saturation. Multivariate regression shows that there is a linear quaternion equation between irreducible water saturation and independent variables such as maximum vitrinite reflectance, volumetric factor, volatile yield, and vitrinite percentage.