Abstract:

As for the gas reservoirs developed with horizontal wells,the production system is consisted of the flow through porous media in the gas reservoirs and the flow in the wellbore of the horizontal well.Pressure drop in horizontal well used to be ignored which results in bigger error in analyzing production system of horizontal wellbore.In this paper,mathematical models of flow through porous media and the flow in horizontal gas wellbore are established by using the concept of production index,then,by means of the volume balance principle,the flow in the gas reservoir is correlated with the flow in the horizontal wellbore,in case of covering flowing states of laminar flow,velvet turbulence and granulate turbulence,the relational expression of pressure drop and productivity with position variation is derived for horizontal wells of the gas reservoir.As an example,the variation law of wellbore pressure and productivity for a horizontal well in a gas reservoir are calculated and analyzed.This article presents a theoretical basis for analyzing production system of horizontal well.

Key words: gas reservoir, horizontal well, wellbore, pressure drop, productivity