Formation fracturing using heat treatment
A downhole tool system includes a downhole tool string configured to couple to a downhole conveyance that extends in a wellbore from a terranean surface through at least a portion of a subterranean zone, the subterranean zone including a geologic formation; and a heating device coupled with the downhole tool string, the heating device configured to transfer heat to the geologic formation in the wellbore at a specified temperature sufficient to adjust a quality of the geologic formation associated with a rock strength of the geologic formation.
1. A downhole tool system, comprising:
a downhole tool string configured to couple to a downhole conveyance that extends in a wellbore from a terranean surface through at least a portion of a subterranean zone, the subterranean zone comprising a geologic formation; and
a heating device coupled with the downhole tool string, the heating device rotatable for 360° about an axis to transfer heat to the geologic formation around a circumferential surface of the wellbore;
a temperature sensor positioned adjacent the heating device; and
a control system communicably coupled to the temperature sensor and the heating device and configured to perform operations comprising:
controlling the heating device to operate to transfer heat to the geologic formation in the wellbore at a specified temperature between 400° C. and 600° C. and a specified time duration between 30 minutes and an hour to reduce a static Young's modulus of the geologic formation to generate one or more fractures in the geologic formation;
receiving a temperature value from the temperature sensor; and
adjust the heating device based, at least in part, on the received temperature value.
2. The downhole tool system of claim 1 , wherein the geologic formation comprises a shale formation.
3. The downhole tool system of claim 2 , wherein the heating device comprises at least one of a microwave heating device, a laser heating device, or an in situ combustor.
4. The downhole tool system of claim 2 , wherein the control system comprises one or more micro-processors.
5. The downhole tool system of claim 2 , wherein the operations further comprise controlling the heating device to focus the heat on a portion of the geologic formation on the circumferential surface of the wellbore.
6. The downhole tool system of claim 1 , wherein the heating device comprises at least one of a microwave heating device, a laser heating device, or an in situ combustor.
7. The downhole tool system of claim 6 , wherein the operations further comprise:
determining that the transferred heat is at a temperature higher than the specified temperature; and
based on the determination, controlling the heating device to output a reduced heat.
8. The downhole tool system of claim 1 , wherein the control system comprises one or more micro-processors.
9. The downhole tool system of claim 8 , wherein the operations further comprise:
determining that the transferred heat is at a temperature higher than the specified temperature; and
based on the determination, controlling the heating device to output a reduced heat.
10. The downhole tool system of claim 1 , wherein the operations further comprise controlling the heating device to focus the heat on a portion of the geologic formation on the circumferential surface of the wellbore.
11. The downhole tool system of claim 1 , further comprising a top sub-assembly configured to couple the heating device to the downhole conveyance.
12. The downhole tool system of claim 1 , further comprising a housing that at least partially encloses the heating device, the housing connected to the top sub-assembly.
13. The downhole tool system of claim 12 , further comprising a bottom sub-assembly connected to the housing and configured to couple to a hydraulic fracturing tool.
14. The downhole tool system of claim 13 , wherein the heating device comprises at least one of a microwave heating device, a laser heating device, or an in situ combustor.
15. The downhole tool system of claim 1 , wherein the specified temperature is between 400° C. and 500° C.
16. The downhole tool system of claim 15 , wherein the heating device comprises at least one of a microwave heating device, a laser heating device, or an in situ combustor.
17. The downhole tool system of claim 1 , further comprising a bottom sub-assembly configured to couple to a hydraulic fracturing tool.
18. The downhole tool system of claim 1 , wherein the operation of receiving a temperature value from the temperature sensor comprises receiving a semi-continual stream of temperature values from the temperature sensor.
19. The downhole tool system of claim 1 , wherein the operation of receiving a temperature value from the temperature sensor comprises receiving a continual stream of temperature values from the temperature sensor.
20. The downhole tool system of claim 1 , wherein the operations further comprise:
determining that the transferred heat is at a temperature higher than the specified temperature; and
based on the determination, controlling the heating device to output a reduced heat.