相对渗透率曲线归一化方法的改进

IMPROVEMENT OF RELATIVE PERMEABILITY CURVE NORMALIZATION METHOD

目前矿场岩心相对渗透率曲线归一化的两种常用方法存在一定的局限性,有必要对其进行有效的改进。幂函数数学模型在归一化岩心的相对渗透率曲线时不能拟合所有类型的相对渗透率曲线,而通过相对渗透率曲线形态影响因素分析,不能拟合的曲线是客观存在的,因此,需要寻找一种适宜所有类型相对渗透率曲线拟合的数学模型方法。同时,也不能用空气渗透率和相对渗透率曲线的束缚水饱和度、残余油饱和度、束缚水饱和度下的相对渗透率之间建立的线性回归关系来对样品筛选后再进行相对渗透率曲线的归一化处理,造成归一化相对渗透率曲线不能客观反映油藏的渗流特征。运用多项式数学模型能够精确拟合有效厚度井段内的所有类型相对渗透率曲线,而且推荐的归一化相对渗透率曲线方法能够隐含参与归一化的每个样品相对渗透率曲线的中间过程点的权重关系,矿场运用后认为多项式数学模型归一化岩心相对渗透率曲线是一种行之有效的方法。

In view of some limitations occurred in the conventional methods for normalization of relative permeability curves from core samples,it is necessary to improve them effectively. The mathematical model of power function can not be used to fit all types of relative permeability curves in the normalization of them,and the curve shape influencing factor analysis indicates that such a not-fitting curve is an objective existence. Therefore,finding a suitable mathematical model for all types of relative permeability curves is necessary. At the same time,using the linear regression relationship established by the relative permeability at irreducible water saturation and residual oil saturation in air permeability and relative permeability curves to select useful core samples followed by running such a normalization results in the normalized curves not objectively reflecting the flow features of reservoir rocks. This paper suggests that using polynomial mathematical model can accurately fit all types of relative permeability curves within effective thickness intervals,also,the recommended normalization method can be implied in the normalized relative permeability curves in the middle of the process of each sample point weight relations. The case study shows that the polynomial mathematical model for normalization of core sample's relative permeability curve is an effective method.