Well Cooling by Down-Ho Circulation of Water

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Abstract
Damage to production wells subjected to the high temperatures associated with in-situ combustion projects has been a problem since the advent of projects has been a problem since the advent of this thermal recovery technique. Injection of water down the annulus of hot wells has been successfully utilized for cooling and prolonging the life of such wells. A mathematical model that is suitable for predicting the effectiveness of cooling water in a predicting the effectiveness of cooling water in a particular application is developed. Typical results particular application is developed. Typical results for practical ranges of the various parameters involved are presented. Introduction: In the normal course of in-situ combustion operations, highly damaging conditions develop in the production wells as the combustion zone approaches, and these wells are subjected to high temperatures (up to 1500F). The resulting well damage is recognized as one of the more serious operating problems unique to the in- situ combustion process. Even in operations where well completions process. Even in operations where well completions have been specially designed to cope with this problem, the question arises as to how this problem, the question arises as to how this destructively high temperature can be kept within tolerable limits. A simple and economical approach to this problem is to circulate cooling water downhole. This method has been used with some success in shallow reservoirs. At greater depths, however, the heat exchange with the overburden surrounding the well and between the fluids in the tubing and the annulus tends to equalize the temperatures of the two fluid streams so that the cooling capacity delivered to the bottom of the hole decreases with well depth. This method would provide no appreciable control over the bottom-hole temperature at great depths. In order to delimit the condition under which cooling by water circulation is effective, the wellbore temperature must be related to the waterinlet rate and temperature; to the reservoir depth, production rate, and initial temperature; and to the production rate, and initial temperature; and to the combustion temperature at bottom-hole depth. A model that meets these requirements and that will offer an approach for developing engineering solutions to practical design and operating problems is described in this paper.

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