Experiment in relative permeabilities and two-phase transient theory
A series of pressure transients were observed at BR21, a high-enthalpy well. The variation in transient behavior with enthalpy gives some indication of the form of relative permeability functions for fractured media. The consistent form of the observed transients indicates that two-phase transient observations can be used to determine reservoir parameters.
The compressibility and hydraulic diffusivity of a water‐steam flow
Physical parameters are defined for a flow of water and steam in a porous medium: dynamic and kinematic viscosity, density, and compressibility. These permit single-phase pressure transient theory to be applied to two-phase flow provided that the pressure changes are not too large.
Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase
Abstract A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir.