Multiple electrical connections to optimize heating for in situ pyrolysis

Patent metadata

Field	Value
Publication number	US-9080441-B2
Application number	US-201213662243-A
Country	US
Kind code	B2
Filing date	Oct 26, 2012
Priority date	Nov 4, 2011
Publication date	Jul 14, 2015
Grant date	Jul 14, 2015

Abstract

A method for heating a subsurface formation using electrical resistance heating is provided. The method includes placing a first electrically conductive proppant into a fracture within an interval of organic-rich rock. The first electrically conductive proppant has a first bulk resistivity. The method further includes placing a second electrically conductive proppant into the fracture. The second electrically conductive proppant has a second bulk resistivity that is lower than the first bulk resistivity, and is in electrical communication with the first proppant at three or more terminal locations. The method then includes passing an electric current through the second electrically conductive proppant at a selected terminal and through the first electrically conductive proppant, such that heat is generated within the fracture by electrical resistivity. The operator may monitor resistance and switch terminals for the most efficient heating. A system for electrically heating an organic-rich rock formation below an earth surface is also provided.

First claim

What is claimed is:

1. A method of heating a subsurface formation using electrical resistance heating, comprising:
placing a first electrically conductive proppant into a fracture within an interval of organic-rich rock, the first electrically conductive proppant having a first bulk resistivity;
placing a second electrically conductive proppant at least partially into the fracture, the second electrically conductive proppant having a second bulk resistivity that is lower than the first bulk resistivity, and the second electrically conductive proppant being in contact with the first electrically conductive proppant at three or more terminals;
passing electric current through the second electrically conductive proppant at a first terminal and through the first electrically conductive proppant, such that heat is generated within the at least one fracture by electrical resistivity;
monitoring resistance in the second electrically conductive proppant at the first terminal; and
switching from the first terminal to a second terminal such that electric current is passed through the second electrically conductive proppant at the second terminal, and through the first electrically conductive proppant to further generate heat within the at least one fracture.

2. The method of claim 1 , wherein the steps of passing electric current heat the subsurface formation adjacent the at least one fracture to a temperature of at least 300° C.

3. The method of claim 1 , further comprising:
monitoring resistance at each of the terminals; and
determining an average resistance over a designated period of time at each of the terminals to evaluate the uniformity of heating in the fracture.

4. A method of heating a subsurface formation using electrical resistance heating, comprising:
forming a first wellbore that penetrates an interval of organic-rich rock within the subsurface formation;
forming at least one fracture in the subsurface formation from the first wellbore and within the interval of organic-rich rock;
placing a first electrically conductive proppant into the at least one fracture, the first electrically conductive proppant having a first bulk resistivity;
placing a second electrically conductive proppant in or adjacent to the at least one fracture, the second electrically conductive proppant being in contact with the first electrically conductive proppant at three or more terminals, and wherein the second electrically conductive proppant has a second bulk resistivity that is lower than the first bulk resistivity;
passing electric current through the second electrically conductive proppant at a first terminal and through the first electrically conductive proppant, such that heat is generated within the at least one fracture by electrical resistivity; and
switching from the first terminal to a second terminal such that electric current is passed through the second electrically conductive proppant at the selected terminal, and through the first electrically conductive proppant to further generate heat within the at least one fracture.

5. The method of claim 4 , wherein:
the subsurface formation comprises bitumen; and
the steps of passing electric current heat the subsurface formation to at least partially mobilize the bitumen within the formation.

6. The method of claim 4 , wherein:
the subsurface formation comprises oil shale; and
the steps of passing electric current heat the subsurface formation to pyrolyze at least a portion of the oil shale into hydrocarbon fluids.

7. The method of claim 4 , further comprising:
providing an electrical source at the surface;
providing a first electrical connection from the electrical source to the second electrically conductive proppant at a first terminal;
providing a separate second electrical connection from the electrical source to the second electrically conductive proppant at a second terminal;
providing a separate third electrical connection from the electrical source to the second electrically conductive proppant at a third terminal; and
monitoring resistance in the second electrically conductive proppant at the first terminal.

8. The method of claim 4 , further comprising:
monitoring resistance at a plurality of the terminals; and
determining an average resistance over a designated period of time at each of the terminals to evaluate the uniformity of heating in the fracture.

9. The method of claim 7 , wherein:
placing a first electrically conductive proppant into the at least one fracture is done by injecting a slurry containing the first electrically conductive proppant from at least the first wellbore;
placing the second electrically conductive proppant in or adjacent to the at least one fracture is done by injecting a slurry containing the second electrically conductive proppant from the first wellbore; and
the second electrically conductive proppant is in electrical communication with the first electrically conductive proppant at the first, second and third terminals along the first wellbore.

10. The method of claim 9 , wherein:
the first wellbore is completed in the interval of organic-rich rock in a substantially vertical orientation; and
the fracture is formed in a substantially vertical orientation.

11. The method of claim 9 , wherein:
the first wellbore is completed in the interval of organic-rich rock in a substantially horizontal orientation;
the second electrically conductive proppant is placed in discrete locations along the first wellbore to form the three or more distinct terminals; and
the fracture is formed in a substantially vertical orientation or in a substantially horizontal orientation.

12. The method of claim 9 , further comprising:
forming a second wellbore that also penetrates the interval of organic-rich rock within the subsurface formation;
forming at least one fracture in the organic-rich rock from the second wellbore and within the interval of organic-rich rock; and
linking the at least one fracture from the second wellbore with the at least one fracture from the first wellbore so that fluid communication is established between the first wellbore and the second wellbore.

13. The method of claim 12 , wherein:
the first wellbore and the second wellbore is each completed in the interval of organic-rich rock in a substantially vertical orientation;
placing a first electrically conductive proppant into the at least one fracture is further done by injecting the slurry containing the first electrically conductive proppant from the second wellbore; and
the fracture is formed between the first wellbore and the second wellbore in a substantially vertical orientation.

14. The method of claim 7 , wherein the second electrically conductive proppant is continuous along the first wellbore.

15. The method of claim 7 , wherein:
the first wellbore is completed in the interval of organic-rich rock in a substantially horizontal orientation; and
the three or more terminals are discrete.

16. The method of claim 7 , wherein:
placing a first electrically conductive proppant into the at least one fracture is done by injecting a slurry containing the first electrically conductive proppant from the first wellbore; and
placing a second electrically conductive proppant in or adjacent to the at least one fracture comprises:
forming two or more second wellbores in addition to the first wellbore, with each of the two or more wellbores intersecting the first electrically conductive proppant in at least one of the one or more fractures; and
injecting the slurry containing the second electrically conductive p

Assignees

• Meurer William P
• Shanley Matthew T
• El-Rabaa Abdel Wadood M
• Exxonmobil Upstream Res Co

Inventors

• Meurer William P
• Shanley Matthew T
• El-Rabaa Abdel Wadood M

Classifications

• E21B43/2401

  by means of electricity · CPC title

• E21B43/267 Primary

  reinforcing fractures by propping · CPC title

• E21B36/04

  using electrical heaters · CPC title