用毛细管压力曲线确定储集层孔隙喉道半径下限

Application of Capillary Pressure to Determination of Cut-off Pore-Throat Radius in Reservoirs

毛细管压力曲线是研究储集层孔隙喉道结构的基础,是油藏评价的重要组成部分。对毛细管压力曲线进行处理即对孔隙喉道半径与进汞饱和度作对数与累计概率图,可以给出类似于粒度概率累计曲线悬浮段的直线段的油藏含义。该段代表的是难流动和不流动孔隙群,可直接读取主要流动孔隙喉道半径的下限值。这一下限值得到了传统求流动孔隙喉道方法和现代核磁研究的验证。另外,将毛细管压力曲线和核磁共振t2谱相结合可以求出含油孔隙喉道半径下限值。

The logarithmic graph and the cumulative probability diagram for pore-throat radius vs mercury injection saturation are presented, in which the straight-line portion similar with the suspending line portion on cumulative grain-size probability curve means the difficult-to-flow and stagnation pore domains in reservoirs, from which the typical cut-off pore-throat radius is read directly and verified by the conventional pore-throat radius method and the modern nuclear magnetic resonance technique. In addition, the combination of capillary pressure curve and spectrum t2 of nuclear magnetic resonance can help to direetly determine the eut-off oil-bearing pore-throat radius.