沉积岩包裹体烃源条件时间温度指数判别法的探讨--以鄂尔多斯下古生界为例

包裹体在油气地质邻域的应用,是近年来包裹体研究的热点和难点。本文探索性地运用沉积岩中包裹体测试数据计算烃源岩主要生烃时期的时间温度指数(TTI),对沉积盆地的烃源条件进行判别。首先利用鄂尔多斯下古生界包裹体显微测温数据求取捕获温度、计算古地温梯度,得出动态古地温曲线;然后计算出下古生界烃源岩的门限。奥陶系烃源岩生烃门限时间为280～131Ma,相当于二叠纪至侏罗纪,其对应的生烃门限温度为70～115℃,门限深度2100～3400m,生烃高峰期为181.4～149.6Ma,相当于侏罗纪中晚期。在生烃高峰期该层位的温度为110～115℃,埋深3300～3400m。和实际主要产气层分布相一致,说明了应用沉积岩包裹体计算时间温度指数,对烃源条件进行判别这种方法的有效性。

TTI Method of Judging Hydrocarbon Source Condition by Fluid Inclusion in Sedimentary Rock

It is prevalent and difficult to study oil-gas by inclusion in recent years. This paper presents time temperature index (TTI) method of judging hydrocarbon source condition by fluid inclusion in sedimentary rock. On the basis of fluid inclusion data of core in Ordos basin , TTI can be calculated out. We first calculate the capture temperatures and the capture pressure by the data of fluid inclusion microanalysis, then calculate the paleo-temperature gradient,the paleo-pressure gradient and the changable palaeo-temperature trajectory. Finally the time domain,the depth domain and the temperature domain of hydrocarbon-production can be worked out. We compare these calculated data with the data calculated in classic way , it shows that the inclusion TTI method is availabe and valid.