利用三维荧光光谱技术确定煤岩成熟度的初步研究

三维荧光光谱(total scanning fluorescence,TSF)技术是一种新的荧光分析技术,在鉴别储层中烃类包裹体、油气运移路径及古油水-现今油水界面方面有着广阔的应用前景。这种技术的主要优点是效率高、所需样品量小且精度高。镜质体反射率(Ro)是确定煤岩成熟度的重要参数,不仅能反映煤岩煤化作用的特征,而且是确定煤阶的重要指标。通过分析采自沁水盆地及淮北煤田的14块煤岩样品的镜质体反射率和三维荧光光谱特征,研究了煤岩荧光光谱特征与镜质体反射率之间的关系。煤岩成熟度与TSF参数R1值具有较好的负相关关系,荧光强度(TSF intensity)与TSF参数R1值具有正相关关系,样品激发光波长与Ro具有负相关关系。实验初步认为TSF技术可以用于煤岩的成熟度评价,但具体的函数关系需要选取更多的煤岩样品进行试验以拟合Ro与激发波长、TSF参数及荧光强度之间的换算关系,建立计算Ro值的经验公式。总之,TSF方法可以快速高效地评价煤岩成熟度,而且不受镜质组组分含量多少的限制,在煤岩成熟度的确定方面有着广泛的应用前景。

Preliminary study on determining Coal Maturity Using Total Scanning Fluorescence Technique

Abstract: Total Scanning Fluorescence (TSF), as a kind of new fluorescence technique, has great significance and wide application in identifying hydrocarbon inclusions of reservoirs, hydrocarbon migration pathways and palaeocurrent oil-water interfaces. Total scanning fluorescence (TSF) is characterized by high efficiency, requiring low sample amount and high accuracy. Vitrinite reflectance (Ro) is one of significant parameters for determining coal ranks, it can not only reflect coalification features, but also provide a favorable indicator for coal maturity. In order to establish a relationship between vitrinite reflectance (Ro) and the characteristic parameters derived from total scanning fluorescence (TSF), fourteen coal samples (coal powder without separating macerals) collected from Qinshui basin and Huaibei coalfield are tested by TSF technique and vitrinite reflectance (oil immersion), respectively. It shows that TSF parameters are related to vitrinite reflectance value, although TSF parameters and fluorescence intensity of coals differ in Qinshui basin and Huaibei coalfield. Research indicates that more factors should be taken into consideration for coal sample TSF testing in the future so as to obtain an empirical formula relationship between Ro and TSF parameters.