Beijing Key Laboratory of Unconventional Natural Gas Geology Evaluation and Development Engineering China
University of Geosciences( Bejing) School of Energy Resources,China University of Geosciences( Beiing)

为了探讨不同性质的气体对低煤阶煤水润湿性的影响,采用低场核磁共振技术,研究了3种条件下湿煤粉饱和水和气(CO2和He)驱替水试验过程中的T2谱的变化。结果表明:湿煤粉饱和水的过程中,CO2的存在能抑制煤样吸水,而He的存在不影响煤样吸水;气驱替水试验过程中,CO2能将煤中的吸附水驱替置换为毛管束缚水,且随着CO2的压力越大,这种置换作用越强;而He不具备这种置换的能力。造成这种现象的可能原因是:CO2对煤具有较强的吸附能力,从而会改变煤表面的性质,减弱煤-水间的相互吸引力、导致煤和水的接触角变大,从而降低煤的亲水性。可见CO2具有改变煤润湿性的能力,而He对煤的润湿性没有影响。

In order to investigate the influences of gases that had different properties on the water- wettability of low rank coal,by used the low- field Nuclear Magnetic Resonance( NMR) Technology,the change of T2 spectrum during the process of water- saturation of wet coal powder under three kinds of condition,and wet coal powder re place with pressurized gases were analyzed. Results showed that in the process of water- saturation of wet coal powder,CO2 could reduce the ability of water imbibitions,b ut not the helium. In the process of the wet coal powder replace with pressurized gases,CO2 could transmit the adsorbed water to capillary water,the effect increased with CO2 gas pressure. In contrast,helium did not have this ability. A possible reason was that CO2 was easily to be adsorbed on coal inner pore surface,and change coal inner- surface property,resulting in a reduction of the interactions of coal- water and an increase of the contact angle of coal- water. It is concluded that CO2 gas has the ability to change the wettability of low rank coal,but helium has no effect on coal wettability.

国家自然科学基金资助项目(41472137,U1262104)；中石油科技创新基金资助项目(2014D-5006-01-02)；全国优秀博士学位论文作者专项资金共同资助项目(201253)；