The 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 correlation of the turbulent term coefficient D(μ) 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(μ)qsc/Fμ (1-rw/rd) in the vertical axis and for the horizontal axis two options are considered: a) D(μi,s)qsc where D(μi,s)=D(μi)f (k/ks),f(k/ks)=β(ks)/β(k) (1–rw/rs)+rw/rs–rw/re, for the case of available estimates for ks and rs and b) sD(μi)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.

Keywords:
turbulent term coefficient, coefficient, transient flow, upstream oil & gas, annual technical conference and exhibition, constant pressure condition, lee, society of petroleum engineers, permeability, bottomhole condition
Subjects:
Formation Evaluation & Management, Drillstem/well testing
Copyright 1991, Society of Petroleum Engineers
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