ROLE OF CAPILLARY FORCES IN VIBRATORY ACTION ON HYDRAULICALLY TREATED GAS-SATURATED COAL

The relevance of the study is governed by the requirement to ensure safety of coal mining in the condition of high gas saturation by means of degassing. One of the ways to improve the quality of degassing is vibro-treatment of coal seam after hydraulic fracturing. The essence of the proposed method consists in the integrated effect exerted on coal seam in two stages continuously coming one after another. At the first stage, a network of large cracks is created in coal (by hydraulic fracturing), and at the second stage, a system of additional small cracks is induced by vibrational impact on the seam, which results in branching of large cracks created at the first stage. This study aims to disclose the physical mechanism of vibrational effect on coal as the method of enhancing capillary impregnation of coal. Results: the effect of capillary fluid transfer occurs when the radii of capillaries are less than 10 microns. The calculations show that the capillary pressure on a liquid meniscus is 4925 Pa at the capillary radius of 10 μm and is 49248 Pa at the capillary radius of 1 μm. The driving force of the capillary fluid transfer acts in the same direction as the force of vibratory displacement and leads to an increase in the amplitude of fluid oscillation in capillaries, which causes an increase in the energy of the carbon–liquid–gas oscillatory system. The vibrational impact on Troinoi coal seam in Komsomolskaya mine of Vorkutaugol has increased permeability of the seam from 0.1–0.001 mD to 1.0–1.1 mD. Vibro-treatment of coal is a method of sufficiently low energy intensity, opening up a new opportunity to use the inertia and elasticity of rock mass to change gaseous state and permeability of coal by creating new systems of cracks and pores.

For citation: Pavlenko M.V., Skopintseva O.V. Role of capillary forces in vibratory action on hydraulically treated gas-saturated coal. Gornyy informatsionno-analiticheskiy byulleten'. 2019;3:43-50. [In Russ]. DOI: 10.25018/0236-1493-2019-03-0-43-50.

Keywords

Gas-saturated coal mass, adsorption capacity of coal, hydraulic treatment of coal seam, degassing, vibrational impact on coal seam, capillary fluid transfer, vibrational displacement.

Issue number: 3
Year: 2019
ISBN: 0236-1493
UDK: 622.807
DOI: 10.25018/0236-1493-2019-03-0-43-50
Authors: Pavlenko M. V., Skopintseva O. V.

About authors: M.V. Pavlenko, Candidate of Technical Sciences, Assistant Professor, Mining Institute, National University of Science and Technology «MISiS», 119049, Moscow, Russia, e-mail: mihail_mggy@mail.ru, O.V. Skopintseva, Doctor of Technical Sciences, Professor, Russian State Geological Prospecting University named after Sergo Ordzhonikidzе (MGRI-RSGPU), 117997, Moscow, Russia, e-mail: skopintseva54@mail.ru. Corresponding author: O.V. Skopintseva, e-mail: skopintseva54@mail.ru.

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