不同煤阶煤层气吸附、解吸特征差异对比

研究煤层气吸附、解吸特征差异，是揭示煤层气成藏机理及高效开发煤层气的基础。高、低煤阶煤层气藏吸附、解吸特征受煤储层物性差异的控制，呈现出显著差别，目前这方面的研究还基本上处于空白。利用煤层气成藏物理模拟及热变模拟实验等手段，研究了高、低煤阶煤层气吸附、解吸特征的根本性差异，并深入剖析了该差异的形成机制。结果显示：高煤阶煤层气藏吸附平衡时间长且较分散，初期相对解吸百分率与相对解吸速率低；低煤阶煤层气藏吸附平衡时间短而集中，初期相对解吸百分率与相对解吸速率高；其化学分子结构、物理结构及显微组分的差异是导致该差异的主要原因。因此，高煤阶煤层气藏解吸效率较低，开发难度较大，低煤阶煤层气藏开发较容易。同时，构造热事件对高煤阶煤储层的改造作用很显著，有助于高煤阶煤层气藏的开发生产。

Comparison of Adsorption/Desorption Properties of CBM in Different-rank Coals

A thorough understanding on the differences of adsorption/desorption properties of CBM is the basis for study of the mechanism of CBM pooling and highly effective development of CBM. The adsorption/desorption properties of CBM in high and low ranks coals, controlled by the physical properties of coal reservoirs, are quite different. Almost no study has been performed in respect of this at present. Experimental methods, such as CBM pooling physical modeling and thermal alteration simulation, are used to systematically study the fundamental differences of adsorption/desorption properties between the high and low rank CBM, and thoroughly analyzes the mechanisms resulting in these differences. For high rank CBM gas reservoir, the adsorption equilibrium time is long and relatively decentralized, and the initial relative desorption percentage and speed are low. In contrast, CBM gas reservoir in low rank coals has a short but centralized adsorption equilibrium time and high initial relative desorption percentage and speed. This is mainly caused by the differences in their chemical molecular structures, physical structures and micropetrological units. Therefore, the modification of tectonic thermal events on high rank coal reservoirs is obvious, and is favorable for production of CBM in high rank coals.