Research On Imbibition Effect Of Injected Water In Coal Containing Gas

The coal seam water injection not only improve the physical strength of coal, but also change the absorption and desorption characteristics of gas due to the microscopic interaction between the moisture and gas in coal. In engineering application, the coal seam water injection is influenced by many factors, the distribution of moisture in coal is indiscipline, it is often exist blanking zone of gas control in injection regional, moreover, the effective range of the wetting coal can not be intuitive judgment, the biggest trouble is easy to be hidden, the “Provisions on Prevention and Control of Coal and Gas Outbursts” which promulgated at 2009 in China also cancelled the regional outburst prevention measures by coal seam water injection, the research on coal seam water injection technology has entered a bottleneck period. The water injection has comprehensive effect on coal gas, which is set high pressure antireflection, displacement, replacement, water lock and other factors as a whole, the effect mainly reflected in two aspects: promote and inhibit the gas desorption, but in the process of water injection, how the single factor to effect and how much contribution that provide, there is no accurate conclusion. In order to solve above problems, we must gradually separate the complex comprehensive function process of water on coal gas, research the mechanism and contribution degree of the single factor.The paper put forward the quantitative study on the single factor of imbibitions of the coal containing gas, and then combines with the experimental research purpose; we independently develop an imbibitions test device of water absorption at constant pressure when the coal is in the high pressure gas adsorption state. It can eliminate antireflection and displacement effect of the high pressure injection, separate study the micro imbibitions of the water into the coal. Through the investigation and comparison of the saturated soaking effect of the coal particle and briquette from the No.3 coal of Yonghong mine, find that briquette is better than coal particle from the water absorption, the water absorption rate, absorption speed and the distribution of water content,the briquette is more suitable for imbibition test. Through the spontaneously water absorbing research of different height of briquette(30mm-80mm), the effect shows that: As the briquette height increase, the water content is increase gradually, but the increasing extent is slowdown, the saturated water adsorptive value tends to be the same, when the height of briquette is 80 mm, the average water absorption rate began to decrease, it is go against the experiment of different water absorption rate, therefore, the briquette height should not exceed 80 mm in the experiment.Use the imbibitions test device of coal containing gas, at the constant temperature of 30℃, we test the imbibition process of briquette under the different absorption equilibrium pressure and constant pressure water absorption, the results showed that: At the same absorption equilibrium pressure, with the increase of constant pressure water absorption, the imbibition gas and imbibition rate are increase gradually, there is a limit water value that can make the imbibition effect the best; At the same water content, with the increase of absorption equilibrium pressure, the imbibition gas is increase gradually, but the imbibition rate is almost constant.Based on the experiment results, and combine with the characteristics of fracture-pore dual medium, theoretical analysis that capillary force is the imbibition dynamic of coal containing gas, the absorption of water molecule is better than methane molecule, provide the material exchange basis.