基于网格过水倍数提高油藏历史拟合精度的方法

Improving reservoir historical matching accuracy based on grid displacing multiple factor

在高含水油藏历史拟合过程中,为了表示水体对岩石孔隙冲刷的影响,往往分阶段进行相渗标定。由于油藏内水驱的不均匀性,统一改变相渗会使水体尚未波及的区域含水上升速度加快,从而影响拟合效果。本文提出采用网格过水倍数来选择不同相渗曲线的方法。网格过水倍数为数值模拟模型中单个网格累积通过水的体积与网格孔隙体积之比,该参数不仅刻画了水驱波及范围,而且描述了波及范围内的水驱强度。在油田开发过程中,随着孔隙过水倍数增加,岩石亲水性增强,相渗曲线向右移动,水相相对渗透率增加。为了模拟储层物性的时变特征,将实验得到的不同过水倍数的相渗曲线输入数值模拟模型中,根据网格过水倍数选取不同的相渗曲线进行拟合,提高了油藏高含水阶段历史拟合精度,对高含水期提高油藏驱油效率和采收率具有重要意义。

In the process of high water cut reservoirhistory matching,the relative permeabilitycurves are often calibrated in stagesto express thewash and brush effect of aquifer on pore structure.Because of the non-uniformity of the water flooding in the reservoir,the uniform change of relative permeability will increase the water cut of the area wherehas not been affected by the aquifer,affecting the historical matching result.In this paper,a method of selecting different relative permeability curves is proposed by using the gird displacing multiple factor.The gird displacing multiple factor is the ratio of the accumulated volume of water flowing through individual grid to the pore volume of this grid in a numerical simulation model.It not only describes the distribution of the water flooding area,but also indicates the flooding strength.The more the volume of aquifer water flow throughthe pore,the higher the rock hydrophilicity gets.As a result,water relative permeability increases with the relative permeability curve shifts to the right.During the numerical simulation process,different relative permeability curves obtained by the experiments are entered into the model,and the selection of the curve for each grid is based on displacing multiple factor.This method has improved the model historical matching precision on the reservoir high watercut stage.It has great importanceonthe increase of the oil displacement efficiency and the oil recovery of during the high water cut period.