System for extraction of hydrocarbons underground

Patent metadata

Field	Value
Publication number	US-9598945-B2
Application number	US-201514746367-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Mar 15, 2013
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A system for in-situ heating of a subsurface formation for the extraction of hydrocarbons in underground deposits is disclosed. The system is configured to heat the underground deposit of hydrocarbons to facilitate fluid flow and hydrocarbon recovery from the underground deposit. The system has an antenna formed from a coaxial transmission line having an annular space between the transmission line outer conductor and the inner conductor and having one or more periodic aperture arrangements along the axial length of the outer conductor. A method for in-situ heating of a subsurface formation for recovering hydrocarbons contained therein is also disclosed. The method comprises: providing an antenna in the subsurface formation; providing electromagnetic RF power to the antenna for heating at least a portion of the subsurface formation.

First claim

What is claimed is:

1. A coaxial antenna for radio frequency (RF) in-situ heating of a subterranean formation, the formation having a 1 st relative electrical permittivity and an electrical conductivity, the antenna having at least an antenna section comprising:
an outer conductor having a longitudinal axis and having a circular cross-section having an inside diameter perpendicular to the longitudinal axis, and further having at least one aperture;
an inner conductor that is coaxial to the outer conductor and having a circular cross-section having an outside diameter; and
an annular space defined by the inside diameter of the outer conductor and the outside diameter of the inner conductor, the annular space containing a dielectric material having a 2 nd relative electrical permittivity that is less than the 1 st relative electrical permittivity;
wherein a ratio b/a of the inside diameter of the outer conductor (b) and the outside diameter of the inner conductor (a) remains uniform along the longitudinal axis for a constant characteristic impedance, and wherein the b/a ratio ranges from 1.5 to 10;
wherein the at least one aperture is arranged for the antenna to have a circumferential radiation of at least 180 degrees along the longitudinal axis;
wherein the antenna has an operational RF power signal frequency from 5 kHz to 20 MHz;
wherein the antenna has a radiation power from 0.5 kW/m to 50 kW/m per longitudinal length of the antenna,
wherein the 1 st relative electrical permittivity ranges from 2.5 to 1000 and the electrical conductivity of the formation ranges from 5.0 Siemens/meter to 4×10 −4 Siemens/meter.

2. The antenna of claim 1 , wherein the at least one aperture is arranged for the antenna to have a full 360 degree circumferential radiation along the longitudinal axis.

3. The antenna of claim 1 , wherein the at least one aperture is arranged for the antenna to have circumferential radiation of at most 180 degrees along the longitudinal axis.

4. The antenna of claim 1 , wherein the antenna comprises at least two antenna sections each with an outer conductor and an inner conductor, and wherein the circular cross-sections of the outer conductors are different, for a step-wise change in characteristic impedance.

5. The antenna of claim 1 , wherein the antenna comprises at least two antenna sections each with an outer conductor and an inner conductor, and wherein the b/a ratio remains the same along the longitudinal axis of the antenna.

6. The antenna of claim 1 , wherein the at least one aperture is configured to have a size and shape selected from rectangular, elliptical, helical, angled, and arbitrary shaped apertures for the antenna to have a predetermined radiation pattern and radiation power within the subterranean formation.

7. The antenna of claim 1 , wherein the at least one aperture is of a radial aperture, a helical aperture, a longitudinal aperture, and combinations thereof.

8. The coaxial antenna of claim 1 , wherein the dielectric material has a relative electrical permittivity in a range from 1 to 25.

9. The coaxial antenna of claim 1 , wherein the dielectric material is any of a gaseous dielectric material, a liquid dielectric material, a solid dielectric material, and combinations thereof.

10. The coaxial antenna of claim 1 , wherein the outer conductor comprises at least one helical aperture having a pitch angle α in a range from 5° to 85°.

11. The coaxial antenna of claim 1 , wherein the at least one aperture has an angular length ranging from 0.5 radians to 36 radians.

12. The coaxial antenna of claim 1 , wherein the coaxial antenna has a proximal end adjacent to an electrical input to the antenna and a distil end farthest from the electrical input, and wherein the coaxial antenna comprises at least a first helical aperture adjacent the proximal end, the first helical aperture having a 1st length in a range from 0.5 to 5 helical windings per aperture; and at least a second helical aperture adjacent the distil end, the second helical aperture having a 2nd length in a range from 1 to 10 helical windings per aperture, the first length being at least ¼ winding greater than the 2nd length.

13. The coaxial antenna of claim 1 , wherein the outer conductor comprises at least two apertures, a 1 st aperture having a 1st pitch angle α 1 and a 2 nd aperture having a 2nd pitch angle α 2 , wherein the 1 st pitch angle α 1 and the 2 nd pitch angle α 2 differs by at least 5° from each other.

14. The coaxial antenna of claim 1 , wherein the antenna has a length in a range from 30 meters to 3000 meters.

15. The coaxial antenna of claim 1 , wherein the at least one helical aperture is sealed with a dielectric material that is transparent to electromagnetic radiation radio frequency range of 5 kHz to about 20 MHz.

16. The coaxial antenna of claim 15 , wherein the dielectric material for sealing the at least one helical aperture has a relative electrical permittivity in a range from 1 to 10.

17. The coaxial antenna of claim 1 , wherein the outer conductor and inner conductor each comprises a conductive material selected from the group consisting of aluminum, aluminum alloys, copper, copper alloys, steel and steel alloys, and combinations thereof, including cladding of steel and steel alloys.

18. The coaxial antenna of claim 1 , wherein the outer conductor and inner conduct each comprises a dielectric material and a conductive layer, and wherein the conductive layer comprises a material selected from aluminum, aluminum alloys, copper, steel, non-magnetic steel, gold, silver, metal alloys, carbon-fibers, graphene and combinations thereof.

19. A system for using the coaxial antenna of claim 1 for radio frequency (RF) in-situ for heating at least a portion of a subsurface formation having a 1 st relative electrical permittivity to a minimum temperature of greater than 60° C.

20. The system of claim 19 , wherein the system comprises: the RF antenna of claim 1 , positioned in a wellbore extending into a subterranean formation and having an RF transparent casing in a hydrocarbon-containing region of the subterranean formation; a generating unit electrically coupled to the RF antenna for generating electromagnetic energy of at least one RF frequency; a transmission line in electrical communication with the generating unit and in electrical communication with the RF antenna for transmitting electromagnetic energy from the generating unit to the RF antenna; and a RF signal generator for supplying harmonic time-varying sinusoidal waveforms to the RF antenna via a transmission system.

Assignees

• Chevron Usa Inc

Inventors

• Okoniewski Michal
• Pasalic Damir
• Vaca Pedro
• Dieckmann Gunther Hans
• Kuehne Donald Leroy
• Vigil Miguel
• Storslett Stein J

Classifications

• H01Q19/10

  using reflecting surfaces · CPC title

• H01Q9/285

  Planar dipole (H01Q9/065 takes precedence; patch antenna H01Q9/0407) · CPC title

• H01Q9/22

  Rigid rod or equivalent tubular element or elements · CPC title

• H01Q1/38

  formed by a conductive layer on an insulating support {(patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface  H01Q15/142)} · CPC title

• Y10T29/49016

  Antenna or wave energy "plumbing" making · CPC title