Control of heat injection based on temperature and in-situ stress measurement

Abstract

The invention is a method to operate a heat injection well, the method comprising the steps of: providing a heat injection well comprising a metal casing and a controllable source of heat within the casing; determining the maximum temperature of the casing which can be applied to the metal casing as a function of external pressure; providing a formation stress measurement device within the formation in the vicinity of the wellbore; providing a temperature measurement device effective for determining the temperature of the casing; determining the formation stress during operation of the heat injection well; and controlling heat released from the controllable source of heat to maintain the formation stress below a predetermined fraction of the collapse stress of the casing. This method significantly reduces conservatism necessary in operation of heat injection wells due to unknown formation stresses, unknown variations in formation stress over the course of heat injection operations, and unknown temperatures of casings.

Dependencies are inferred from the claim text.