Rescaled exponential and density-based decline models

Extension to variable- rate/pressure-drawdown conditions

Luis Ayala H., Miao Zhang

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Constant-bottomhole-pressure (BHP) solutions to the diffusivity equation are used routinely for the analysis of well-decline performance in boundary-dominated flow (BDF). Gas-well-performance equations for constant-BHP conditions may be written in a number of ways, including rate vs. pseudopressure, rate vs. pseudotime, rate vs. material-balance pseudotime expressions, and, more recently, in terms of density-based rescaled exponential models (Ayala and Ye 2013a, b; Ye and Ayala 2013). A significant constraint for some of these models, especially for the rescaled exponential model, is the assumption that BHP conditions remain constant throughout the declining life of the well. However, the most realistic well-specification scenario is that in which both BHP and flow rate decline in time (i.e., a variablepressure- drawdown/-rate condition). In this study, we explore and prove the validity of rescaled exponential and density-based gas decline models for the analysis of variable-rate/pressure-drop gas systems in BDF. We also demonstrate that the constant-rate and constant-BHP solutions given by the proposed density-based decline models for gas wells under BDF are interchangeable.

Original languageEnglish (US)
Pages (from-to)433-440
Number of pages8
JournalJournal of Canadian Petroleum Technology
Volume52
Issue number6
StatePublished - Jan 1 2013

Fingerprint

Gases
Pressure drop
Flow rate
Specifications

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology

Cite this

@article{82aafaf60c7c4cea84dc6ebd9d15fb10,
title = "Rescaled exponential and density-based decline models: Extension to variable- rate/pressure-drawdown conditions",
abstract = "Constant-bottomhole-pressure (BHP) solutions to the diffusivity equation are used routinely for the analysis of well-decline performance in boundary-dominated flow (BDF). Gas-well-performance equations for constant-BHP conditions may be written in a number of ways, including rate vs. pseudopressure, rate vs. pseudotime, rate vs. material-balance pseudotime expressions, and, more recently, in terms of density-based rescaled exponential models (Ayala and Ye 2013a, b; Ye and Ayala 2013). A significant constraint for some of these models, especially for the rescaled exponential model, is the assumption that BHP conditions remain constant throughout the declining life of the well. However, the most realistic well-specification scenario is that in which both BHP and flow rate decline in time (i.e., a variablepressure- drawdown/-rate condition). In this study, we explore and prove the validity of rescaled exponential and density-based gas decline models for the analysis of variable-rate/pressure-drop gas systems in BDF. We also demonstrate that the constant-rate and constant-BHP solutions given by the proposed density-based decline models for gas wells under BDF are interchangeable.",
author = "{Ayala H.}, Luis and Miao Zhang",
year = "2013",
month = "1",
day = "1",
language = "English (US)",
volume = "52",
pages = "433--440",
journal = "Journal of Canadian Petroleum Technology",
issn = "0021-9487",
publisher = "Canadian Institute of Mining",
number = "6",

}

Rescaled exponential and density-based decline models : Extension to variable- rate/pressure-drawdown conditions. / Ayala H., Luis; Zhang, Miao.

In: Journal of Canadian Petroleum Technology, Vol. 52, No. 6, 01.01.2013, p. 433-440.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Rescaled exponential and density-based decline models

T2 - Extension to variable- rate/pressure-drawdown conditions

AU - Ayala H., Luis

AU - Zhang, Miao

PY - 2013/1/1

Y1 - 2013/1/1

N2 - Constant-bottomhole-pressure (BHP) solutions to the diffusivity equation are used routinely for the analysis of well-decline performance in boundary-dominated flow (BDF). Gas-well-performance equations for constant-BHP conditions may be written in a number of ways, including rate vs. pseudopressure, rate vs. pseudotime, rate vs. material-balance pseudotime expressions, and, more recently, in terms of density-based rescaled exponential models (Ayala and Ye 2013a, b; Ye and Ayala 2013). A significant constraint for some of these models, especially for the rescaled exponential model, is the assumption that BHP conditions remain constant throughout the declining life of the well. However, the most realistic well-specification scenario is that in which both BHP and flow rate decline in time (i.e., a variablepressure- drawdown/-rate condition). In this study, we explore and prove the validity of rescaled exponential and density-based gas decline models for the analysis of variable-rate/pressure-drop gas systems in BDF. We also demonstrate that the constant-rate and constant-BHP solutions given by the proposed density-based decline models for gas wells under BDF are interchangeable.

AB - Constant-bottomhole-pressure (BHP) solutions to the diffusivity equation are used routinely for the analysis of well-decline performance in boundary-dominated flow (BDF). Gas-well-performance equations for constant-BHP conditions may be written in a number of ways, including rate vs. pseudopressure, rate vs. pseudotime, rate vs. material-balance pseudotime expressions, and, more recently, in terms of density-based rescaled exponential models (Ayala and Ye 2013a, b; Ye and Ayala 2013). A significant constraint for some of these models, especially for the rescaled exponential model, is the assumption that BHP conditions remain constant throughout the declining life of the well. However, the most realistic well-specification scenario is that in which both BHP and flow rate decline in time (i.e., a variablepressure- drawdown/-rate condition). In this study, we explore and prove the validity of rescaled exponential and density-based gas decline models for the analysis of variable-rate/pressure-drop gas systems in BDF. We also demonstrate that the constant-rate and constant-BHP solutions given by the proposed density-based decline models for gas wells under BDF are interchangeable.

UR - http://www.scopus.com/inward/record.url?scp=84901064303&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84901064303&partnerID=8YFLogxK

M3 - Article

VL - 52

SP - 433

EP - 440

JO - Journal of Canadian Petroleum Technology

JF - Journal of Canadian Petroleum Technology

SN - 0021-9487

IS - 6

ER -