In situ thermal recovery from a relatively permeable formation with backproduction through a heater wellbore
A method for treating a relatively permeable formation containing heavy hydrocarbons in situ may include providing heat from one or more heat sources to a portion of the formation. The heat may be allowed to transfer from the heat sources to a selected section of the formation. The transferred heat may pyrolyze at least some hydrocarbons within the selected section. A temperature proximate a selected portion of a heater well may be selectively limited to inhibit coke formation at or near the selected portion. A mixture of at least some hydrocarbons may be produced through the selected portion of the heater well.
1. A method for treating a relatively permeable formation in situ, comprising:
providing heat from one or more heaters to at least a portion of the formation;
allowing the heat to transfer from the one or more heaters to a part of the formation such that the heat pyrolyzes at least some hydrocarbons within the part of the formation;
selectively limiting a temperature proximate a selected portion of a heater wellbore to inhibit coke formation at or near the selected portion; and
producing at least some hydrocarbons through the selected portion of the heater wellbore.
2. The method of claim 1 , further comprising generating water in the selected portion to inhibit coke formation at or near the selected portion of the heater wellbore.
3. The method of claim 1 , wherein the heater wellbore is placed substantially horizontally within the part of the formation.
4. The method of claim 1 , wherein selectively limiting the temperature comprises providing less heat at the selected portion of the heater wellbore than other portions of the heater wellbore in the part of the formation.
5. The method of claim 1 , wherein selectively limiting the temperature comprises maintaining the temperature proximate the selected portion below a pyrolysis temperature of about 270° C.
6. The method of claim 1 , further comprising one or more production wells, and producing a mixture from the part of the formation through at least one of the production wells.
7. The method of claim 1 , further comprising providing at least some heat to an overburden section of the heater wellbore to maintain the produced hydrocarbons in a vapor phase.
8. The method of claim 1 , further comprising maintaining a pressure in the part of the formation below about 150 bars absolute.
9. The method of claim 1 , further comprising producing hydrocarbons when a partial pressure of hydrogen in the formation is at least about 0.5 bars.
10. The method of claim 1 , wherein the heat provided from at least one of the heaters is transferred to at least a portion of the formation substantially by conduction.
11. The method of claim 1 , wherein a ratio of energy output of the produced mixture to energy input into the formation is at least about 5.
12. The method of claim 1 , wherein the produced mixture comprises an acid number less than about 1.
13. A method for treating a relatively permeable formation in situ, comprising:
providing heat from one or more heaters to at least a portion of the formation;
allowing the heat to transfer from the one or more heaters to a part of the formation such that the heat pyrolyzes at least some hydrocarbons within the part of the formation;
controlling operating conditions at a production well to inhibit coking in or proximate the production well; and
producing a mixture the from part of the formation through the production well.
14. The method of claim 13 , wherein controlling the operating conditions at the production well comprises controlling heat output from at least one of the heaters proximate the production well.
15. The method of claim 13 , wherein controlling the operating conditions at the production well comprises reducing or turning off heat provided from at least one of the one or more heaters for at least part of a time in which the mixture is produced through the production well.
16. The method of claim 13 , wherein controlling the operating conditions at the production well comprises increasing or turning on heat provided from at least one of the one or more heaters to maintain a desired quality in the produced mixture.
17. The method of claim 13 , wherein controlling the operating conditions at the production well comprises producing the mixture at a location sufficiently spaced from at least one of the heaters such that coking is inhibited at the production well.
18. The method of claim 13 , further comprising adding steam to the part of the formation to inhibit coking at the production well.
19. The method of claim 13 , further comprising producing the mixture when a partial pressure of hydrogen in the formation is at least about 0.5 bars.
20. The method of claim 13 , wherein the heat provided from at least one of the heaters is transferred to at least a portion of the formation substantially by conduction.
21. The method of claim 13 , wherein a ratio of energy output of the produced mixture to energy input into the formation is at least about 5.
22. The method of claim 13 , wherein the produced mixture comprises an acid number less than about 1.