石油学报 ›› 2020, Vol. 41 ›› Issue (6): 737-744.DOI: 10.7623/syxb202006008

• 油田开发 • 上一篇    下一篇

致密气自扩散渗流模型

金衍1, 韦世明1, 陈康平2, 夏阳1   

  1. 1. 中国石油大学(北京)油气资源与探测国家重点实验室 北京 102249;
    2. 亚利桑那州立大学 美国亚利桑那州 85287-6101
  • 收稿日期:2019-05-18 修回日期:2020-01-22 出版日期:2020-06-25 发布日期:2020-07-11
  • 通讯作者: 金衍,男,1972年8月生,1994年获石油大学(华东)学士学位,2001年获石油大学(北京)博士学位,现为中国石油大学(北京)教授、研究生院常务副院长、长江学者特聘教授,主要从事石油工程岩石流固耦合力学与应用研究。
  • 作者简介:金衍,男,1972年8月生,1994年获石油大学(华东)学士学位,2001年获石油大学(北京)博士学位,现为中国石油大学(北京)教授、研究生院常务副院长、长江学者特聘教授,主要从事石油工程岩石流固耦合力学与应用研究。Email:jiny@cup.edu.cn
  • 基金资助:

    国家自然科学基金项目(No.51874321)和国家自然科学基金青年科学基金项目(No.51904318)资助。

Self-diffusion flow model of tight gas

Jin Yan1, Wei Shiming1, Chen Kangping2, Xia Yang1   

  1. 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China;
    2. Arizona State University, Arizona 85287-6101, USA
  • Received:2019-05-18 Revised:2020-01-22 Online:2020-06-25 Published:2020-07-11

摘要:

致密气藏已经开始在世界上大规模开发,但其基本渗流机理尚不明确,现有渗流模型难以对生产数据进行完善的解释。笔者介绍并通过实例对Jin和Chen (2019)提出的新渗流模型及其适用性进行了研究。Jin和Chen从可压缩流体的N-S方程出发,基于Klainerman和Majda (1982)的小马赫数流动理论,利用渐近展开,多尺度分析和体积平均升尺度技巧,得到了时间尺度大于声波时间尺度时致密气藏一次开采油藏尺度下新的渗流方程。新的渗流方程反映了致密气藏一次开采完全是由气体的膨胀性驱动的物理本质,其扩散系数与孔隙度和气体黏度成正比,与气体密度成反比。通过实例对比自扩散模型与目前基于Darcy定律及其修正的渗流模型发现,Darcy渗流以及组合流动模型得到的气体产量仅在生产压差较小时才能与实际生产数据吻合,此时的产量较小;生产压差越大,Darcy渗流模型与实际生产数据偏差越大;而自扩散模型计算的产量能够较好地拟合实际生产数据。

关键词: 致密气, 渗流机理, 一次开采, 可压缩流体N-S方程, 自扩散, 生产

Abstract:

Tight gas reservoirs have begun to be exploitated on a large scale in the world, of which the basic flow mechanism is still unclear. It is difficult to perfectly interpret production data using the existing flow models. Through the comparison of actual cases, this paper introduces and explores the new flow model proposed by Jin and Chen (2019)and its applicability by examples. According to the N-S equation of compressible fluids and based on the theory of Klainerman and Majda (1982)for low Mach number flow, Jin and Chen obtained the new flow equation for the primary recovery of tight gas reservoirs on the reservoir scale in the case of time scale greater than the acoustic time scale using asymptotic expansion, multi-scale analysis and the upscaling technique of volume averaging. The new flow equation reflects the physical nature that the primary recovery of tight gas reservoirs is driven entirely by the expansibility of gas, and its diffusion coefficient is proportional to porosity and gas viscosity, and inversely proportional to gas density. The comparison by case studies between the self-diffusion model and the current flow model based on the Darcy's law and its modification shows that the gas yield obtained by the Darcy and combined flow model can only be consistent with the actual production data when the producing pressure drop is small, and the gas yield at this time is small; the larger the producing pressure drop, the greater the deviation between the Darcy flow model and the actual production data; the gas yield calculated by the self-diffusion model can well fit the actual production data.

Key words: tight gas, flow mechanism, primary recovery, N-S equation of compressible fluid, self-diffusion, production

中图分类号: