考虑优势通道发育的层状水驱油藏开发指标预测方法

摘要

高含水期层状水驱油藏普遍发育优势通道,与常规油藏渗流特征不同,注入水在优势通道中的流动可视为高速非达西渗流,但现有的层状水驱油藏开发指标预测方法尚未考虑优势通道的影响.为此,基于油藏工程和渗流力学理论,考虑注入水在优势通道中的高速非达西渗流,推导并建立了层状水驱油藏开发指标预测方法.该方法可以计算优势通道发育的层状水驱油藏的含水率和采出程度等开发指标,定量反映优势通道渗透率和厚度对油藏开发动态的影响.实例分析表明,随着优势通道渗透率和厚度的增大,油藏层间矛盾更加突出,小层中正常储层的采出程度降低,优势通道中注水量增大,注水利用率降低,油藏整体开发效果变差.该方法准确地反映了优势通道发育的层状水驱油藏的生产特征,可用于指导该类油藏的开发调整.%Large numbers of preferential flow paths exist in the multi-layer waterflooding reservoirs in high water cut stage.Being different with general oil reservoirs,the injection water obeys high velocity non-Darcy flow in the preferential flow paths.However,the present methods of development index prediction for the multi-layer waterflooding reservoirs do not take the preferential flow paths into account.Based on reservoir engineering theory and fluid mechanics in porous medium,considering the high velocity non-Darcy flow of injection water in the preferential flow paths,a method of development index calculation for multi-layer waterflooding reservoir was derived and proposed.This method can calculate the development indices such as water cut and oil recovery degree.It can reflect the effect of permeability and thickness of the preferential flow paths on production performance quantitatively.Results present that the interlayer contradiction increases with the increasing of permeability and thickness of the preferential flow paths.The recovery degree of normal reservoirs in the layer decreases.The injected water volume of the preferential flow path becomes larger,resulting in lower utilization factor of water injection and worse development effect.This method can exactly reflect the production characteristic of multi-layer waterflooding reservoir with preferential flow path and it can be used to guide the development adjustment for this kind of reservoir.