煤层气降压开采机理研究

Mechanism for Coalbed Methane Production

模拟计算了解吸时间、渗透率、等温吸附线形态、压差、含气饱和度等方面因素对煤层气产量高低的影响,分析了煤层气产出的机理。研究表明,低含气饱和程度、低地层压力、低渗透是造成我国煤层气产量较低的原因;解吸时间越短,气产量高峰期越早,高峰期产量越高,高峰期过后产量下降也越快;相渗曲线越陡,残余气饱和度越小对气产出越有利;等温吸附线在地层压力变化范围内的缓陡程度决定气产量的高低。

The effects of desorption time, permeability isothermal absorption curve shapes, pressure difference, oil and gas saturation on the degree of coalbed methane production are calculated and its producing mechanism is analyzed by simulation. The study shows that low gas saturation, low formation pressure, and low permeability are the causes of China's low coalbed methane production, the shorter desorption time is, the earlier gas production peak period is, the higher peak production is, the fast production decrease will be after production peak period. The steeper permeability curve is, the smaller residual gas saturation is, the more beneficial gas production will be. The curve steep degree of isothermal absorption within formation pressure change extent determines the gas production.