摘要
本文通过对大量数据的统计和分析,论述了柴达木盆地现今地温基本特征,总结了油气区、油气田的地温显示;在此基础上恢复了新生界生油层的地温历史,运用康南时温关系图式和TTI法,探讨了各生油层的成热门限和热演化进程,总结了盆地生油演化的基本状况和主要特征。
The Qaidam Basin is a large oil-gas basin with the highest geo-thermal intensity in the Northwestern areas of China. The relationship formula of the temperature and depth is. T= 3.201H+9.960, and the representative geo-ther mal gradient is 3.2℃/100m. The calculated terrestrial heat flow value is 60m w/m2 or so. On the border of the basin there is an evident low-temperature zone, and the geothermal gradient is 1 -3℃/100m. In those vast areas of the basin the geothermal distribution is relatively even, and the geothermal gradient is usually 3 -4℃/100m.
The related formula between the threshould temperature of oil generation and the age of the Cenozoic source rocks in the Qaidam Basin is. logt = 2857×1/T - 6.143. The critical TTI values of the different evolutional stages are as follows ; mature point is 5; the high peek of oil-generation is 90; the high mature point is 230. The main effective source rocks in the basin are the lower Ganchaigou Formation of the Oligocene series and the upper Ganchaigou Formation of the Miocene series in the Tertiary. Their present mature threshould values are 95-106℃, 2600-3100m. They might enter the mature stage in the early Pliocene Epoch or in the Miocene Epoch. At that time, their mature threshould values were 110-125℃ ,2600-3800m respectively. At present, its principal body is being in the oil-generating peek stage, and the partial area has developed into a higher mature stage or an over mature stage.
The basic characteristics of the source evolution in the Qaidam Basin are as follows ; the evolutional speed is fast; the evolutional degree is high; the mature horizon is young, and the evolutional stage is complete.
关键词
盆地
地温
新生代
生油岩
热演化
<keywords>Qaidam Basin, geotemperature, Cenozoic, Oil-source rocks, heat evolution
