Patent ID: 9464514
Filing Date: 2016-10-11
CPC Classification: E21B

Claim Text:
1. A downhole heating system for delivery of thermal energy to a horizontal wellbore located in a subterranean formation via a connected vertical wellbore that provides a heated heat transfer fluid from a thermal fluid heater positioned above ground on the surface, said system comprising: a steam chamber separated by a thermal packer assembly and positioned at a downhole position of the vertical wellbore, said steam chamber having at least one heat exchanger and perforations to direct steam from the steam chamber into the horizontal wellbore; and a heat transfer fluid closed loop system which comprises concentric strings for flow of the heated heat transfer fluid, cooled transfer fluid and hot feedwater, wherein an innermost first string and a second string of the concentric strings connect the heater to heat exchanger to supply the heated heat transfer fluid through the vertical wellbore to the heat exchanger and return the cooled transfer fluid from the heat exchanger to the surface thermal fluid heater for reheating, and a third string of the concentric strings to provide the hot feedwater to the steam chamber, wherein the heat exchanger has tubing which transfers heat from the heated heat transfer fluid to the hot feedwater to generate steam in the steam chamber and cause heating of a subterranean region via the thermal energy added by the steam from the steam chamber being directed into the horizontal wellbore through the perforations.