煤储集层解吸特征及其影响因素

中国煤层气储集层的解吸特征受多种因素影响,不同地区差异很大.煤层气解吸率一般在40%左右,多小于70%,主要与煤层原位含气量和储集层压力等因素有关.煤层气解吸时间主要为0.188 3～19.17d,随着煤阶的增高解吸时间有增大的趋势,其中以高煤阶煤岩吸附时间跨度最大,最高可达30d之上.统计大量实验数据发现,煤层形态、温度、煤阶、灰分含量、含气量、割理发育程度、沉积环境与煤岩类型是影响煤岩吸附时间的主要因素.根据数值模拟的结果,煤岩解吸量影响煤层气井的单井产量,解吸量越大单井产量越大.煤岩的吸附时间主要影响煤层气井产量峰值的大小和出现的时间,吸附时间越长,煤层气井产气高峰出现得越晚且峰值越小.图6参16

Desorption characteristics of coalbed methane reservoirs and affecting factors

The desorption characteristics of coal beds in China are affected by many factors. The desorption ratio of coalbed gas is about 40%, and mostly less than 70%, and it is affected by gas content and coal bed pressure. Most of the desorption time values are between 0. 188 3 to 19.17d, and the time span of high rank coal is the biggest which can reach over 30d. The value has a positive correlation with coal rank. A great number of experimental data shows that temperature, coal dimension and shape, coal rank, ash content, gas content, cleat, sediment environment, and coal style are the main affecting factors of desorption time. According to the numerical simulation result, coal desorption volume affects the single well production, and the single well output has a positive correlation with the desorption. The variation of coal desorption time value can induce the change of output peak value of a single well and its occurring time.