Pressure and temperature drawdown well testing: similarities and differences

Abstract

Temperature and pressure are the most frequently observed physical parameters in boreholes. The same differential diffusivity equation describes the transient flow of incompressible fluid in porous media and heat conduction in solids. The similarities and differences in the techniques of pressure and temperature well testing are discussed. It is shown that the mathematical model of pressure well tests based on the presentation of the borehole as an infinitely long linear source with a constant fluid flow rate in an infinite-acting homogeneous reservoir cannot be used in temperature well testing. A new technique has been developed for the determination of the formation thermal conductivity, initial temperature, skin factor and contact thermal resistance. It is assumed that the volumetric heat capacity of formations is known and the instantaneous heater's wall temperature and time data are available for a cylindrical probe with a constant heat flow rate placed in a borehole. A semi-analytical equation is used to approximate the dimensionless wall temperature of the heater. A simulated example is presented to demonstrate the data processing procedure.