C、O同位素在川东北碳酸盐岩储层研究中的应用

通过对川东北鸡唱地区碳酸盐岩的C、O同位素分析,结合岩石薄片镜下研究和阴极发光分析及前人的研究成果,探讨飞仙关组三级海平面变化趋势和白云岩化作用机理.为了便于分析,将样品分为泥晶灰岩和白云岩两组.泥晶灰岩的C、O同位素分析结果表明:δ13C全为正值,明显分为两段,先快速上升、然后低辐振荡下降,指示海平面在飞一段初期快速...

Application of Carbon and Oxygen Isotope to Carbonate Reservoirs in Northeast Sichuan Basin

The trend of third order sea level changes and mechanism of dolomitization are studied, based on C, O isotope analysis of carbonate rocks, as well as microscopic research, CL analysis, and previous studies of Feixianguan Formation in Jichang of northeast Sichuan Basin. In convenience to analysis, the samples were grouped into two sets of micrite limestone and dolomite. The C, O isotope analysis of micrite limestone shows that the value of δ13C are all positive, and two stages are clear, that is, the first stage is a fast rising stage and followed a falling stage with a wave shape. The result suggests that the sea level increases quickly in the early First Section of Feixianguan Formation, then, shows a slowly falling trend with sublevel fluctuation after maximum flooding surface. The δ13C evolution curve is rising totally, which is in accord with the rising trend of the Triassic global sea level. The implications of δ18O on the sea level changes is obscure, due to the processes of late diagenesis. The C, O isotope analysis of dolomite shows that the orthogonal points of δ13C (0.91‰~2.09‰) and δ18O ( 3.45‰~ 9.29‰) fall in the second quadrant. The result, combining with microscope studies and cathodeluminescent analysis, suggests that dolomitization was formed in the buried condition.