结合高温高压物性实验确定致密油储层充注物性下限新方法

DETERMINATION OF THE PHYSICAL PROPERTY LOWER LIMIT OF TIGHT OIL RESERVOIR BY HIGH-TEMPERATURE AND HIGH-PRESSURE EXPERIMENT

致密油储层的开采物性下限变得越来越低,并且逐渐接近成藏充注物性下限,因此对于致密油储层物性下限的精确确定变得极为重要.束缚水水膜厚度在确定储层物性下限中起到关键作用,其中束缚水表面积通过氮气吸附实验可以精确得到.束缚水水膜体积的得出方法很多,但也存在很多缺陷.通过对多种方法的调研,最后确定采用模拟地层压力和温度的岩电实验,结合阿尔奇公式得到束缚水饱和度,计算出束缚水水膜体积的方法,最后得出的束缚水膜厚度.此法可以很好地模拟地层环境,所得结果更加接近地层真实值,最后得出的束缚水水膜厚度更加准确.束缚水水膜得出以后,与孔喉半径平均值建立关系图确定孔喉半径平均值下限,然后运用统计学原理建立孔喉半径平均值与孔渗的关系图,最终确定致密油储层的孔隙度充注下限值和渗透率下限值.根据压汞曲线图确认此种测试方法所得物性下限结果准确.

The physical property lower limit for mining of tight oil reservoir is becoming lower and lower,gradually approaching that of accumulation filling.Therefore,it is significantly important to accurately determine such lower limit.The bound water film thickness plays a key role in the determination,while the surface area of bound water can be obtained accurately by nitrogen adsorption experiment.There are quite a few defects despite many methods to determine the volume of bound water film.Through investigating various methods,the rock-electric experiment which simulates the formation pressure and temperature is finally adopted,combined with the Archie formula to calculate the saturability,then the volume and finally the thickness of bound water film.The method can well simulate the strata environment,with result closer to the true value,thus the obtained bound water film thickness is more accurate.The low limit of pore throat mean radius is determined by establishing its relation to the bound water film thickness.Then,with principle of statistics,the relation between the pore throat mean radius and permeability is set up to finally decide the low limit of porosity filling and permeability of tight oil reservoir.The results prove to be accurate according to the mercury injection curve.