低渗透油藏启动压力梯度新算法及应用

A NEW METHOD AND THE APPLICATION ON CALCULATING START-UP PRESSURE GRADIENT IN LOW PERMEABLE RESERVOIRS

针对目前大多数低渗透油层的渗流研究都是通过岩芯驱替实验得到渗透率与启动压力梯度的关系,不仅费时费工,而且考虑的因素比较单一的问题。通过对中国西部某低渗油田不同渗透率岩芯室内驱替实验,从流体在低渗透多孔介质渗流机理出发,对实验数据进行处理和回归分析,建立了新的物理模型,提出了一种求解启动压力梯度的新方法,得到求解低渗透油藏启动压力梯度数学模型。由数学模型可以得到启动压力梯度的主要影响因素是驱动压力梯度、流体的流度,启动压力梯度与前者成正比关系,与后者成反比关系。利用求解启动压力梯度的数学模型,结合低渗透油田实际,研究了启动压力梯度对单井产量、极限注采井距和含水上升率的影响。

At the present, to the research flowing through porous media in most of low permeable reservoirs, the relation between permeability and start-up pressure gradient is dained by core flooding experiment, which is time-consuming and highly costed, and also, the factors taking into consideration are simple. Through the core flooding experiment, the core samples are from a certain low permeable reservoir in west China and with different permeability, processing and regression analysis of the data are carried on based on the mechanism of fluid flowing through low permeable porous media, a new physical model is set up, a new method studing start-up pressure gradient is presented, and the mathematical model soluting start-up pressure gradient of low permeable reservoir is gained. From the model, it can be derived that the main factors impacting start-up pressure gradient are driving pressure gradient and the fluid mobility, there is a positive relation between start-up pressure gradient and driving pressure gradient, and a negtive relation between start-up pressure gradient and the mobility. By means of the mathematical model soluting start-up pressure gradient and practice of low permeable reservoir, the influence of start-up pressure gradient on single well productivity, ultimate distance between producer and injector and water content increasing rate are studied.