Acta Petrolei Sinica ›› 2023, Vol. 44 ›› Issue (10): 1693-1705,1738.DOI: 10.7623/syxb202310009

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Establishment and application of general equation for production decline

Wang Rui, Xue Longlong, Dang Dongqi, Gao Wenjun   

  1. Research Institute of Exploration and Development, PetroChina Tuha Oilfield Company, Xinjiang Hami 839009, China
  • Received:2023-05-10 Revised:2023-08-25 Online:2023-10-25 Published:2023-11-03

产量递减方程通式的建立及应用

王睿, 薛龙龙, 党东琪, 高文君   

  1. 中国石油吐哈油田公司勘探开发研究院 新疆哈密 839009
  • 通讯作者: 高文君,男,1971年3月生,1994年获大庆石油学院学士学位,现为中国石油吐哈油田公司勘探开发研究院高级工程师,主要从事油藏工程与提高采收率研究工作。Email:gaowj7132@petrochina.com.cn
  • 作者简介:王睿,女,1995年1月生,2017年获重庆科技学院学士学位,现为中国石油吐哈油田公司勘探开发研究院工程师,主要从事油气藏工程研究工作。Email:wangrkt@petrochina.com.cn
  • 基金资助:
    中国石油天然气股份有限公司"十四五"前瞻性基础性科技项目(2021DJ1106)资助。

Abstract: With the continuous development of unconventional oil-gas reservoirs, it has been quite difficult for the traditional Arps decline equation to describe the production decline process of large-scale volume fracturing and horizontal wells in unconventional oil-gas reservoirs. Therefore, by summarizing and studying the mathematical model of the existing production decline equation, the observation time in Arps production decline differential equation is replaced by a composite function that has time attribute and reflects the development and change of oil-gas reservoir system, and a general production decline equation with more general adaptability has been established. Under certain conditions, this general equation can be transformed into various existing common production decline equations, and also form new high-precision production decline equations. It is expected that in the future, the research of production decline equation will mainly focus on the determination of the relationship between composite function and decline time. Once the new relationship between composite function and decline time is determined, a new production decline equation can be formed. Meanwhile, for the convenience of application, the paper systematically provides the calculation method of the general production decline equation under the condition of two kinds of relationship between composite function and decline time. Through practical applications, it has been found that it is highly effective to use the time-varying structure estimation method and perform fitting between the general equation of production decline when T=mtb and the production decline curve of unconventional oil reservoirs in Ma 56 wellblock, and the estimated production is very close to the actual value.

Key words: production decline equation, observation time, composite function, general decline equation, least square method, time-varying structure estimation

摘要: 随着非常规油气藏相继投入开发,传统的Arps递减方程已很难适应描述非常规油气藏大型体积压裂+水平井的产量递减过程。为此,通过对已有产量递减方程数学模型梳理与研究,将Arps产量递减微分方程中的观察时间替代为反映油气藏系统发展变化、且具有时间属性的复合函数,建立了更具普遍适应性的产量递减方程通式,该通式在一定条件下可以转化为已有的各种常用产量递减方程,也可形成新的拟合精度较高的产量递减方程。产量递减方程研究的重点将主要集中在复合函数与递减时间关系式的确定上,一旦确定了新的复合函数与递减时间关系式,就能形成新的产量递减方程。同时,为了应用方便,系统性给出了两种复合函数与递减时间关系式的情况下产量递减方程通式的计算方法。通过应用实例发现,采用时变结构预估方法,利用T=mtb时产量递减方程通式拟合吐哈油田马56区块非常规油藏生产井的产量递减曲线效果更好,预估产量更接近实际值。

关键词: 产量递减方程, 观察时间, 复合函数, 递减方程通式, 最小二乘法, 时变结构预估

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