西南石油大学学报(自然科学版)

• 石油与天然气工程 • 上一篇    下一篇

叠加原理不能求解含启动压力梯度渗流方程

李道伦1,2 *,杨景海3,查文舒2,王磊4,卢德唐1   

  1. 1. 合肥工业大学应用数学系,安徽合肥230009;2. 中国科学技术大学力学系,安徽合肥230027;
    3. 中国石油大庆油田测试技术服务分公司,黑龙江大庆163453;4. 中国科学院核能安全技术研究所,安徽合肥230031
  • 出版日期:2015-08-01 发布日期:2015-08-01
  • 通讯作者: 李道伦,E-mail:LdaoL@ustc.edu.cn
  • 基金资助:

    国家科技重大专项(2011ZX05009 006);国家重点基础研究发展计划(2011CB707305);中国科学院战略性先导科技专项(XDB1003-
    0402)。

Unsuitability of Using Superposition Principle to Solve Equation Incorporated with Threshold Pressure Gradient

Li Daolun1,2*, Yang Jinghai3, Zha Wenshu2, Wang Lei4, Lu Detang1   

  1. 1. Department of Applied Mathematics,Hefei University of Technology,Hefei,Anhui 230009,China
    2. Department of Modern Mechanics,University of Science and Technology of China,Hefei,Anhui 230027,China
    3. Logging & Testing Services Company,Daqing Oilfield Co. Ltd.,Daqing,Heilongjiang 163453,China
    4. Institute of Nuclear Energy Safety Technology,Chinese Academy of Science,Hefei,Anhui 230031,China
  • Online:2015-08-01 Published:2015-08-01

摘要:

由于含启动压力梯度的渗流方程不是齐次方程,使用叠加原理对其进行求解时会引起误差。首先建立含启动
压力梯度的渗流方程,然后基于PEBI 网格进行数值求解,最后将数值计算的试井曲线与基于叠加原理的试井曲线进
行对比。数值求解的计算结果表明:启动压力梯度使得关井后的井底压力很快稳定,并且井底压力不能恢复到原始压
力,同时,关井段的压力导数曲线下掉。基于叠加原理的计算结果表明:启动压力梯度使关井后的井底压力持续上升、
数百天乃至数千天都不能使恢复压力稳定,并且压力导数上翘。这不仅与数值解有很大的差别,而且也与封闭边界压
力导数下掉的趋势相悖。这表明叠加原理不适用来求解含启动压力梯度的渗流方程。

关键词: 启动压力梯度, 低渗透, PEBI 网格, 数值求解, 试井曲线

Abstract:

Equation incorporated with threshold pressure gradient(TPG)is not homogeneous,and the error exists if it is solved
based on superposition principle. A mathematical single-phase flow model incorporated with the threshold pressure gradient
is proposed to describe the flow behavior in low permeability reservoirs by coupling the well storage effect. The fully implicit
numerical simulation based on PEBI grid is developed to study the transient pressure response for a vertical well. Buildup
pressure based on numerical simulation shows that TPG quickly makes buildup pressure stabilize,and makes buildup pressure
lower than initial pressure,and thus leads to the drops of curves of pressure derivative during buildup period. However,buildup
pressure based on superposition principle increases with time and cannot stabilize even after 4 800 days,which makes curves of
pressure derivative go up during buildup period. Comparing well test curves based on numerical solution with well test curves
based on superposition principle,we find that solution based on superposition principle is totally different from the solution
based on numerical simulation,which exhibits that superposition principle cannot be used to solve flow equation incorporated
with threshold pressure gradient.

Key words: threshold pressure gradient, low permeability, PEBI gridding, numerical solution, well test curves