鄂尔多斯盆地上古生界储层中包裹体最小捕获压力的PVTsim模拟

Simulation for minimum trapping pressure of inclusions occurring in Upper Paleozoic sandstone reservoir of Ordos Basin using PVTsim

应用传统的方法求取包裹体的捕获压力存在许多问题。近几年发展起来的PVTsim软件已广泛应用于计算含油气盆地中液态烃包裹体的捕获压力,然而利用该软件计算缺乏液态烃包裹体的天然气藏储层中包裹体的捕获压力的文章尚未见报道。在对鄂尔多斯盆地上古生界储层砂岩中次生盐水包裹体进行有关测定和分析的基础上,利用PVTsim软件对该类包裹体捕获压力进行了模拟计算。结果表明,包裹体的最小捕获压力为16～21MPa,并有从南向北逐渐减小的趋势,而且包裹体的捕获压力远小于深盆气藏形成时的静水压力,这一特征与深盆气藏形成的地质地球化学条件相一致。

There are many problems on the investigation of the trapping pressure of inclusions by means of the conventional methods. Recently, the PVTsim has been widely applied to determination of the trapping pressure of petroleum inclusions in gas and oil bearing basin. However, there is no publication about the calculation of the trapping pressure of the inclusions in gas field where there have no petroleum inclusions by this method. In this paper, the trapping pressure of the secondary aqueous inclusions occurring in the Upper Paleozoic of Ordos Basin is calculated on the basis of the relative analytical data. The results show that the minimum trapping pressures of the aqueous inclusions vary from 16 to 21 MPa, with a tendency to decrease from south to north direction, and they are much lower than the state water pressures during the inclusions formation. This is consistent with the geological and geochemical conditions for the formation of deep basin gas trap.