东营凹陷镜质体反射率异常的无机作用探讨

东营凹陷取芯井镜质体反射率(Ro)受到了抑制,从上部的0.60%向下逐渐降为0.45%.从有机地球化学,特别是地球化学作用角度分析了镜质体反射率异常的原因,从有机地球化学角度看,Ro值随腐泥组分的增加而减少,富氢有机质抑制Ro的增长;从无机地球化学角度看,研究段内自下而上水体逐渐变淡,酸性有所增强,酸性环境有利于有机质的成熟演化.Ro异常层段内钾、钠、镁、锂变化不大,与Ro没有明显的对应关系;钙、锰、锶、硼与Ro呈负相关关系,它们抑制了Ro的增加;铁、钡、钴、锌、镍、铷等与Ro呈正向相关关系,它们催化了Ro的增加.

Inorganic geochemical explanation of abnormal vitrinite reflectance: taking Niu-38 well in Dongying Sag,Jiyang Depression as an example

The vitrinite reflectance of Niu-38 well is restrained, it decreases from 0.6% of the upper to 0.45% of the lower of cored interval. The causes leading to the abnormality of the vitrinite reflectance are analyzed from organic geochemistry and inorganic geochemistry separately. The explanation from organic geochemistry is that, vitrinite reflectance decreases with the increase of the contents of sapropelic components, and hydrogen-rich organic matters restrain the increase of the vitrinite reflectance. From inorganic geochemistry, the study results in this paper show that, the information water in the studied interval becomes fresh and its acidity becomes a little strong from the lower to the upper. The acidic condition is favorable to the maturation of organic matters. In the studied interval, the contents of K, Na, Mg and Li vary a little, therefore, there are no correlations between them and vitrinite reflectance; there are negative correlations between the contents of Ca, Mn, Sr and B and vitrinite reflectance, they maybe restrain the increase of vitrinite reflectance; there are positive correlations between the contents of Fe, Ba, Co, Zn, Ni and Rb and vitrinite reflectance, they maybe promote the increase of vitrinite reflectance.