2种氧化剂对贫煤孔隙特性影响的对比研究

为探讨过硫酸铵与二氧化氯对贫煤孔隙特征的影响,优选出更加适合贫煤储层改造的氧化剂,对采集自大平矿与告成矿的贫煤煤样进行压汞实验,分析讨论了过硫酸铵与二氧化氯对煤样孔隙度、分形维数和排驱压力等储层基本特征参数以及孔体积、比表面积及其分布的影响。结果表明,二氧化氯能够有效提高煤储层的孔隙度,减小其孔比表面积及分形维数,过硫酸铵则可能导致煤储层总体孔隙度降低,减小孔比表面积,增大其分形维数。二氧化氯与过硫酸铵作用后,煤样大孔孔体积所占比例增加,中、小及微孔体积比例减小,使孔隙分布更加均匀,各类孔比表面积分布变化不大。因此,二氧化氯与过硫酸铵均能够对贫煤储层进行氧化刻蚀,降低其亲甲烷能力,而二氧化氯对煤层气解吸运移的促进作用要优于过硫酸铵。

Comparative Study on Effect of Two Oxidants on Pore Characteristics of Lean Coal

To explore the influence of ammonium persulfate and chlorine dioxide on pore characteristics of lean coal and to optimize the oxidant which is more suitable for the coal reservoir reconstruction, lean coal samples from Daping Mine and Gaocheng Mine were collected for mercury injection experiment. The effects of ammonium persulfate and chlorine dioxide on porosity, fractal dimension, drainage pressure, pore volume, specific surface area and distribution of coal samples are discussed.The results show that chlorine dioxide can effectively improve the porosity of coal reservoir, reduce its specific surface area and fractal dimension, and ammonium persulfate may lead to a decrease in the overall porosity of coal reservoir, reduce the specific surface area of reservoir, and increase its fractal dimension. After the interaction of chlorine dioxide and ammonium persulfate, the proportion of large pore volume in coal sample increased, while the proportion of medium, small and micro pore volume decreased,making pores more uniform and the specific surface area of various pores did not change much. It is concluded that both chlorine dioxide and ammonium persulfate can oxidize and etch the reservoir of lean coal and reduce its methanophile ability. The effect of chlorine dioxide on desorption migration of CBM is better than that of ammonium persulfate.