试用数学地质法研究陕甘宁盆地上古生界煤系地层热演化

MATHEMATICAL GEOLOGY RESEARCH ON THE THERMAL EVOLUTON OF PALEOZOIC COAL-SERIES OF SHANGANNING BASIN

王少昌 傅锁堂

wang Shaochang Fu Suotang

石油工业部长庆石油勘探开发研究院

Research Institute of Changqing Oilfield

本文据煤层中所测的镜质体反射率(Ro)代表煤系热演化地温指数的论点、煤热模拟试验过程中热演化指标(Ro)随温度成函数递变的规律,研究煤系地层在不同地史过程中的Ro值与其影响因素的内在联系。 陕甘宁盆地上古生界煤系地层分布面积达二十三万平方公里。据现有资料,笔者整理了井下及地面123个煤样的Ro数据及二十一口井Ro值纵向变化资料,利用四口深井井温曲线及部分中、深试油井井温曲线作参照对比,结合区域构造及地质发展历史对上古生界煤系地层中Ro值及主要影响因素之间的关系、用数学地质的方法进行了赏试性的联系。从而应用于油气勘探。

Shanganning Basin is a major Mesozoic inland basin with an area of 230000Km2. There are evident differences in geothermic gradient depending on the burial depth of Mono-discontinuity. Using the relationship between temperature and vitrinite reflectance, it is possible to obtain the apparent palaeo-geothermic gradient which bears an inverse linear relation-ship to the burial depth of mohorovicic discontinuity. It is revealed that the value of vitrinite reflectance representing the maturity index of the upper palaeozoic source rock depends on the burial depth of mohorovicic discontinuity and that of the source rock itselt, and an equation for relating them has been worked out. Using multiple regression analysis for vitrinite reflectance, and the burial depth of mohorovicic discontinuity and the source rock, an empirical equation has been deduced to give the quantitative parameters for evaluating the hydrocarbon source rock of a new area and the erosional magnitude to be restored.

https://doi.org/10.11781/sysydz198601050