新疆准南地区煤储层显微裂隙特征及矿物控因分析

Analysis on microfracture characteristics and control action of mineral genesis of coal reservoir in south margin of Junggar Basin,Xinjiang

为进一步提高和深化对我国低煤阶煤储层特征的理解和认识,基于显微光度计和扫描电镜能谱(SEM-EDS)分析,对取自新疆准噶尔盆地南缘地区(简称淮南地区)的25块煤岩样品的显微裂隙和矿物特征进行了系统研究。结果表明:准南地区煤储层显微裂隙极其发育,构造成因的外生裂隙非均质性程度要明显强于内生裂隙的,外生裂隙可以指示区域构造发育程度及构造煤存在的可能性。发育内生裂隙煤样中所含的矿物极少,以自生矿物为主,其次为陆源碎屑矿物,未见后生成因矿物;而发育外生裂隙煤样所含矿物种类较多、含量较高,以后生矿物为主,其次为自生高岭石,陆源碎屑矿物少见。煤储层中外生裂隙多被方解石充填且矿物充填呈现多期性,而内生裂隙的矿物多期充填则相对较少。

To further improve and deepen the understanding of the low rank coal reservoir characteristics in our country,microffacture and mineral genesis of 25 coal samples from the southern Junggar Basin of Xinjiang had been systematically analyzed based on the micro spec- trophotometer,scanning electron microscopy and energy dispersive spectrum （SEM-EDS） analysis. The results showed that the microfrae- tures in the research area were well developed. Exogenous fracture heterogeneity was much stronger than the endogenetie fracture, exoge- nous microfractures could indicate the complexity of regional tectonics and the possibility of the tectonic coal. The mineral conlent of coal samples that endogenous fractured developed was less, mainly by authigenic minerals, followed by the terrigenous clastie minerals, no epige- netic genesis minerals; however, the mineral types and content in coal sample that exogenous fissure developed was more and higher, domi- nated by epigenetic mineral followed by authigenic kaolinite, terrigenous clastic mineral was rare. Fluid exchange could easily occur in the exogenous microfracture, and exhibited a multi-period mineral filling. Many of the exogenous microfracture are filled with calcite, hut multi -period mineral filling in endogenous nlicrofracture is relatively small.