Rediscovering Non-Darcy Flow Effect in Gas Reservoir

Document Type

Conference Proceeding

Publication Date

1-1-2003

Abstract

The paper demonstrates and explains the importance of global inclusion (i.e. throughout the reservoir) of Non-Darcy (N-D) flow component for better prediction of well performance in gas reservoirs with bottom water drive by using a numerical simulator. Traditionally, Non-Darcy flow effect in gas reservoirs has been attributed only to high gas flow rates, and considered locally around the. wellbore. Consequently, most numerical simulators have the N-D component assigned to the well rather than distributed throughout the reservoir. Also, the common judgment is that the effect is insignificant at gas rates lower than 10 MMscf/d, so it would not affect gas recovery in the low-rate wells. In this project, we used an analytical model, field data, and a numerical simulator with global and local N-D component to study sensitivity of final recovery and gas rate to N-D flow for a variety of reservoir properties. The results show that disregarding the N-D flow globally leads to overestimation of cumulative gas recovery by up to 42.2 percent. Moreover, this overestimated recovery is the same when N-D is ignored, or assigned locally to the wellbore. It is also shown that N-D effect is significant at low production rates. Shown is the range of reservoir properties where gas wells producing only 9.8 MMscf/D would have total pressure draw-down comprising 70% contribution of N-D flow effect.

Publication Source (Journal or Book title)

Proceedings - SPE Annual Technical Conference and Exhibition

First Page

399

Last Page

406

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