Variable-rate pressure-drawdown analysis of gas wells with turbulence and damage

Ibrahim S. Nashawi, Ahmed A. Elgibaly, Reyadh A. Almehaideb

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1 Citation (Scopus)


Over the years, several approaches have been proposed to solve the problems associated with the analysis of conventional gas well tests. For instance, pseudo-pressure has been effectively employed to partially linearize the diffusivity equation describing real-gas flow in the reservoir. Variable-rate tests were suggested as an excellent substitute for the constant-rate test. Trial-and-error procedure and multirate tests were applied to determine the rate-dependent skin of high-flow-rate wells. Even though these techniques, in general, provide good estimates of the reservoir characteristics, they are time-consuming and hard to apply in practice. This paper presents a simple and straight-forward technique to analyze variable-flow-rate drawdown data of gas wells with turbulence and damage. The proposed technique provides accurate estimates of the reservoir parameters by using two different plots. The formation permeability and the non-Darcy flow coefficient are respectively determined from the slope and the intercept of the first plot, whereas the mechanical skin factor is obtained from the intercept of the second plot. Field and simulated cases are used to illustrate the application of the proposed technique. The method has the advantage of providing more accurate and reliable results in a relatively short testing time over the current conventional and type-curve matching techniques. It is also handy when nonlinear regression is not preferred.

Original languageEnglish
Pages (from-to)291-320
Number of pages30
JournalIn Situ
Issue number3
Publication statusPublished - 1998

ASJC Scopus subject areas

  • General Chemical Engineering
  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology
  • Energy Engineering and Power Technology


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