A Method for Gas Well Decline Analysis Under Constant Pressure Conditions and High-Velocity Flow J. Vega-P.; J. Vega-P. U. Industrial de Santander Search for other works by this author on: This Site Google Scholar F. Samaniego-V.; F. Samaniego-V. Pemex/UNAM Search for other works by this author on: This Site Google Scholar S. Berumen C. S. Berumen C. Pemex Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 1991. Paper Number: SPE-22926-MS https://doi.org/10.2118/22926-MS Published: October 06 1991 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Vega-P., J., Samaniego-V., F., and S. Berumen C. "A Method for Gas Well Decline Analysis Under Constant Pressure Conditions and High-Velocity Flow." Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 1991. doi: https://doi.org/10.2118/22926-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractThe correlation most widely used for predicting the rate decline of gas wells is that of Lee, Logan and Tek, which was derived from results of different constant rate production conditions. This paper presents the results of a study aimed at obtaining a presents the results of a study aimed at obtaining a correlation of the turbulent term coefficient D(mu) for constant pressure bottomhole conditions. Results were acquired through a radial real gas flow simulator, carefully tested for pseudosteady state conditions. The skin effect considered varies from 0 to 10. Two different gases are considered and other variables are the constant pressure, the reservoir size re/rw and formation permeability. The correlation is presented by means of log-log straight line fits of D(mu)qsc/f mu (1-rw/rd) in the vertical axis and for the horizontal axis two options are considered:D(mu i,s)qsc where D(mu i,s)=D(mu i)f(k/ks),f(k/ks)= Beta(ks)/Beta(k) (1-rw/rs)+rw/rs-rw/re, for the case of available estimates for ks and rs andsD(mu i)qsc if the above mentioned estimates are not available; the correlation coefficient was 0.99968 for option a) and 0.99920 for option b) An easy method for predicting rate decline under transient and pseudosteady state conditions is presented.IntroductionThe prediction of the rate behavior of a well is one of the basic endeavors of a reservoir engineer. With the increasing demand of energy, gas has steadily gained importance as energy supplier. The literature shows a number of papers dealing with the decline of gas wells. References 1-29 are a sample of these studies.For gas well decline predictions and for the interpretation of transient well tests, high-velocity flow effects if present must be taken properly into account. These effects are represented in terms of a high velocity pseudoskin D(mu)qsc, where D(mu) is the turbulent term coefficient. During production of a gas reservoir the average Pressure decreases, resulting in an increase of D(mu). It has been demonstrated that for constant pressure producing conditions, the high-velocity pseudoskin D(mu)qsc decreases with time On the opposite, for constant rate production conditions the pseudoskin D(mu)q sc increases with time.Several papers discuss the rate decline of homogeneous and fractured gas wells considering high-velocity effects. These studies can be classified in two groups. The first presents results, obtained through numerical simulations and other methods, by means of type curves. The second group presents analytical methods for the prediction of gas well decline, with the assumption that the turbulent term coefficient D(mu), is estimated from the Lee, Logan and Tek correlation. This correlation was derived from results of different constant rate production conditions, including simulation results and examination of field data.This paper presents the results of a study aimed at obtaining a correlation of the turbulent term coefficient D(mu) for constant pressure bottomhole conditions. An alternate easy method for predicting rate decline under transient and pseudo-steady state conditions is discussed.MATHEMATICAL AND NUMERICAL MODELTo formulate the mathematical model, the following assumptions usually made in well test analysis are applied. The reservoir has radial geometry with a closed outer boundary and is composed of a horizontal porous formation, that has uniform and isotropic rock porous formation, that has uniform and isotropic rock properties and constant thickness. However a radial properties and constant thickness. However a radial region of reduced permeability near the wellbore, as described by Hawkins, is considered. The reservoir model is essentially that considered by Wattenbarger an Ramey, except by the inner boundary condition that for our case is of constant pressure.P. 407 Keywords: turbulent term coefficient, coefficient, transient flow, upstream oil & gas, annual technical conference and exhibition, correlation, simulation, gas well decline analysis, drillstem testing, constant pressure condition Subjects: Formation Evaluation & Management, Drillstem/well testing This content is only available via PDF. 1991. 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