Patent ID: 9670761
Date: 2017-06-06
CPC Classifications: E21B

Claim:
1. A method, comprising: heating a heat transfer fluid; continuously circulating the heated heat transfer fluid into a vertical wellbore to a downhole heat exchanger positioned in a steam chamber of the vertical wellbore via tubing; advancing heated feedwater into the vertical wellbore to the downhole heat exchanger in concentricity with the tubing carrying the heated heat transfer fluid to further heat the heated feedwater flowing downward in the vertical wellbore above a packer assembly, the packer assembly being provided in a downhole position of the vertical wellbore above the downhole heat exchanger, wherein the downhole heat exchanger is configured to transfer heat from the heated heat transfer fluid to the heated feedwater to generate steam and return the heated heat transfer fluid via the continuous circulation from the downhole heat exchanger for reheating; controllably feeding the heated feedwater below the packer assembly via a feed valve provided by the packer assembly, wherein the heated feedwater flashes into steam below the packer assembly via the heat transfer from the heat exchanger; transmitting the steam from the downhole heat exchanger into a subterranean formation, whereby thermal energy from the steam causes a reduction in viscosity of hydrocarbons in the subterranean formation; injecting, via an acid wash line that is separate from the tubing, an acid scale wash to counter scale buildup on the downhole heat exchanger from the heated feedwater; returning the heated heat transfer fluid from the downhole heat exchanger via the continuous circulation to a surface thermal fluid heater; recovering liquefied oil deposits from the hydrocarbons in the subterranean formation in a horizontal wellbore; and transmitting the recovered liquefied oil deposits to above ground through a production line.