The Importance of Joule-Thomson Heating (or Cooling) in Temperature Log Interpretation
Authors: Steffensen Roger J. , Smith Robert C. 
Published: December 2007

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
This paper shows how knowledge of the Joule-Thomson effect can aid temperature log interpretation. The effect is a cooling of produced or injected gas, or a warming of produced or injected gas, or a warming of injected water, due to pressure drop in flow through the formation and perforations. This influences shut-in temperature behavior, and thus is important in temperature log interpretation. A key conclusion is that the shut-in temperature profile is influenced not only by the previous flow rate profile, but also by the permeability profile. Methods for quantitative interpretation (i.e., determination of injection rate profiles) are reviewed, in light of this conclusion.

Introduction
Joule-Thomson heating of water and cooling of gas are of interest because they can have a significant influence on temperatures in and around production and injection wells, and thus on temperature log interpretation. The heating or cooling occurs as a result of pressure drop during flow within the pressure drop during flow within the formation and through perforations. Thus the Joule-Thomson effect (JTE) influences the temperature distribution in the formation during flow. This distribution then determines the rate of wellbore temperature change (at flow zone depths) after shut-in, since these changes are due to conductive heat transfer.
Information presented herein on the JTE is based on theoretical analysis, on computer modeling such as that presented in Ref. 1, and on examination of temperature logs from a number of wells. The influence of the JTE on both qualitative and quantitative interpretation of temperature logs is discussed.
Although portions of this paper are presented in terms of radial flow systems, the presented in terms of radial flow systems, the same ideas also apply for linear (i.e., vertically fractured) systems. For both types of systems, convective heat transfer and the JTE significantly influence the temperature distribution near a well during flow and thus the wellbore temperature behavior after shut-in.

DEFINITION OF THE JOULE-THOMSON EFFECT
The JTE is the change in temperature of a fluid upon expansion (i.e., pressure decrease) in a steady flow process involving no heat transfer nor work (i.e., at constant enthalpy). This occurs in "throttling" type processes such as adiabatic flow through a processes such as adiabatic flow through a porous plug or an expansion valve. In the porous plug or an expansion valve. In the original experiment by Joule and Thomson, the throttling was accomplished by flowing gas through a cotton plug.