The Effect of Water Vaporization on the Well Productivity in High Temperature Gas Reservoirs

Abstract

Flow of gas through porous media at high velocity is affected by inertial forces resulted from convective acceleration of fluid particles in the medium, as well as viscous force, as explained by Darcy's equation. The inertial force further develops the additional skin effect, reducing gas production rate. At early stages of production, the pressure drop in the near-well region builds up the molar content of water in gas. This, in turn, results in water vaporization and hence a drop in the connate water saturation. Considering the fact that inertial force is a function of the non-Darcy coefficient, β, which itself is dependent on connate water saturation, this can ultimately reduce the non-Darcy component of pressure drop and therefore inertial forces. The present study focuses on the enhancement of gas well productivity through water vaporization.

Keywords:

• gas reservoirs
• non-Darcy flow
• simulation
• water vaporization
• well productivity

NOMENCLATURE

DQ	=	=  Rate dependent skin factor
h	=	=  Thickness of formation
Kj	=	=  Effective permeability of phase j
m(p)	=	=  Pseudo pressure
	=	=  Average reservoir pressure
Q	=	=  Gas flow rate, MMSCFD
r	=	=  Radius, ft
re	=	=  External radius, ft
S	=	=  Skin factor
Swi	=	=  Connate water saturation
U	=	=  Fluid velocity
Z	=	=  Compressibility factor

Symbols

β	=	=  Inertial coefficient
ф	=	=  Porosity
ρ	=	=  Density
μ	=	=  Viscosity