The Relationship Between Wettability And Gas Production For The 3~# Anthracite Coal Collected From Sihe Coal Mine

Through the experiments combined with theoretical analysis, the impacts of coal material composition and pore structure on coal wettability are predicted through partial wetting agents and reverse wetting agents when material composition and pore structure analysis are conducted for the 3~# coal collected from Sihe coal mine and the wettability of the coal is measured based on the measurement of inorganic rock wettability. The connection between the macro coal petrography composition and coal wettability is preliminarily identified by means of the measurement of vitrain and durain wettability; meanwhile, the desorption features, coalbed methane desorption ration & recovery ration and thermodynamic features are analyzed for the coal samples with various moisture contents through the CH4 isothermal adsorption and desorption experiments for the coal samples with various moisture contents; furthermore, proper gas production system is discussed for the coalbed gas in high-order coal areas based on the No. 1 well gas production data in Sihe as the subsection of gas production curve is done for three CBM vertical wells in Sihe and the hydraulic parameters in coal reservoir is set to analyze the connection of water production and gas production.The results show as follows: the coal petrography compositions of 3~# anthracite reservoir in Sihe present high vitrinite, low inertinite and minerals with small amount of clay; also it presents the low porosity- the porosity of vitrain is higher than that of vitrain- and that vitrain band is beneficial for the CH4 circulation in primary- structured coal areas while the durain band is good for the CH4 adsorption accumulation; 3~# coal in Sihe has a poor wettability and the vitrain has a relatively rich wettability; 6501, JFC and laundry powder are used as wetting agents in favor of coal adsorption of water molecules while g502 solution is as a reverse wetting agent in favor of a hydrone reversed; the 3~# coal in Sihe with rich moisture contents has a weak adsorption of CH4; the coal with poorer moisture content has a higher theoretical desorption ration and gas production ration; and it conforms to the E negative exponential attenuation for the daily gas production/cumulative gas production & daily water production/cumulative water production for vertical wells in Sihe coalbed methane. Analog calculation shows that the gas production at 2.5 m3/d water production is far higher than that at 1.8m3/d. Adding reverse wettability agents in coal reservoir is in favor of dehydration to increase the hydrophobicity of coal reservoir; it helps to prevent velocity sensitive & stress sensitivity as well as to appropriately increase the drainage intensity in favor of coalbed methane desorption and output.