The paper demonstrates and explains the importance of globalinclusion (i.e. throughout the reservoir) of Non-Darcy (N-D)flow component for better prediction of well performance ingas reservoirs with bottom water drive by using a numericalsimulator. Traditionally, Non-Darcy flow effect in gasreservoirs has been attributed only to high gas flow rates, andconsidered locally around the wellbore. Consequently, mostnumerical simulators have the N-D component assigned to thewell rather than distributed throughout the reservoir. Also, thecommon judgment is that the effect is insignificant at gas rateslower than 10 MMscf/d, so it would not affect gas recovery inthe low-rate wells.In this project, we used an analytical model, field data, and anumerical simulator with global and local N-D component tostudy sensitivity of final recovery and gas rate to N-D flow fora variety of reservoir properties. The results show thatdisregarding the N-D flow globally leads to overestimation ofcumulative gas recovery by up to 42.2 percent. Moreover, thisoverestimated recovery is the same when N-D is ignored, orassigned locally to the wellbore.It is also shown that N-D effect is significant at lowproduction rates. Shown is the range of reservoir propertieswhere gas wells producing only 9.8 MMscf/D would havetotal pressure draw-down comprising 70% contribution of NDflow effect.
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