Apparatus and method for controlled temperature heating of volumes of hydrocarbonaceous materials in earth formations

• US 4,470,459 A
• Filed: 05/09/1983
• Issued: 09/11/1984
• Est. Priority Date: 05/09/1983
• Status: Expired due to Fees

• Current Assignee: Halliburton Company
• Original Assignee: Halliburton Company
• Inventors: Copland, George V.
• Primary Examiner(s): Suchfield, George A.
• Application Number:
  US06/492,975
• Time in Patent Office: 491 Days
• Field of Search: 166/52, 166/50, 166/60, 166/65 R, 166/245, 166/248, 166/302
• US Class Current: 166/248
• CPC Class Codes: E21B 36/04 using electrical heaters
• CPC Class Codes: E21B 43/2401 by means of electricity
• CPC Class Codes: E21B 43/305 comprising at least one inclined or horizontal well
• CPC Class Codes: H05B 2214/03 Heating of hydrocarbons

Abstract

The disclosure relates to a technique for controlled or uniform temperature heating of a volume of hydrocarbonaceous material in an earth formation employing conductor arrays, inserted in the formation, for applying radio frequency energy to the formation. The number and spacing of conductors in the arrays are selected to provide a concentration of electric field intensity at the extremities of the volume to facilitate controlled or uniform temperature heating of the volume. The arrangement compensates for temperature variations across the volume caused by heat flow within the volume and heat loss to the surrounding formation.

Claims

1. An apparatus for in situ heating of a volume of a hydrocarbonaceous formation to convert kerogen therein to recoverable oil and gas comprising:

electrical excitation means for providing an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz; and

conductor arrays, electrically connected to said excitation means and inserted in spaced boreholes in the formation, and comprising means for providing a relatively greater concentration of field intensity about conductors near the surface of said volume and a relatively lesser concentration of field intensity about conductors in the interior of said volume, thereby compensating for heat flow in the volume and heat loss to the formation surrounding said volume.

2. The apparatus of claim 1 wherein the arrays are arranged to define the heated volume to be recovered as having a surface to volume ratio less than that of a cube of equal volume.

3. A method for in situ heating of a volume of a hydrocarbonaceous formation to permit recovery of hydrocarbon products therein, comprising:

generating an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz;

providing a first outer row of borehole penetrating the formation, adjacent boreholes being separated by a distance less than 1/4 of the wavelength of the electrical signal;

providing a second outer row of boreholes penetrating the formation, adjacent boreholes being separated by a distance less than 1/4 of the wavelength of the electrical signal, said second outer row being parallel to and spaced from said first outer row of boreholes;

providing a central row of boreholes penetrating the formation, adjacent boreholes being separated by a distance less than 1/4 of the wavelength of the electrical signal, said central row being parallel to and spaced between said first and second outer rows of boreholes;

inserting elongated conductors into at least some of said boreholes;

interconnecting at least some adjacent conductors of the central row;

selectively applying said electrical signal to said interconnected conductors of the central row and selected conductors of the outer rows to heat a first, volume in the formation and to provide a concentration of field intensity about at least some of the electrodes near the extremities of said volume to compensate for heat flow in the volume and heat loss to the formation surrounding said volume to effect a substantially uniform temperature rise throughout the volume; and

selectively applying the electrical signal to conductors in different boreholes in the rows to heat a different volume in the formation.

4. An apparatus for in situ heating of a volume of a hydrocarbonaceous formation comprising:

means for generating an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz;

a first outer row of elongated conductors penetrating the formation, adjacent elongated conductors being separated by a distance less than 1/4 of the wavelength of the electrical signal;

a second outer row of elongated conductors penetrating the formation, adjacent boreholes being separated by a distance less than 1/4 of the wavelength of the electrical signal, said second outer row being parallel to and spaced from said first outer row of conductors;

a central row of conductors penetrating the formation, adjacent conductors being separated by a distance less than 1/4 of the wavelength of the electrical signal, said central row being parallel to and spaced between said first and second outer rows of conductors;

means for selectively interconnecting the conductors of the central row; and

means for selectively applying said electrical signal to said interconnected conductors of the central row and selected conductors of the outer rows to heat volumes in the formation and to provide a concentration of field intensity about at least some of the electrodes near the surface of said volumes to compensate for heat flow in the volume and for heat loss to the formation surrounding said volume.

5. An apparatus for in situ heating of a volume of oil shale to convert kerogen in the oil shale into oil and gas for recovery comprising:

electrical excitation means for providing an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz;

a central conductor array, electrically connected to said excitation means, comprising a line of approximately parallel conductors inserted in approximately horizontal boreholes in the formation;

an upper conductor array, electrically connected to said excitation means, comprising at least one conductor inserted in a borehole approximately parallel to the conductors of said central conductor array and located above said central conductor array; and

a lower conductor array, electrically connected to said excitation means, comprising at least one conductor inserted in an approximately horizontal borehole located below said central conductor array;

said conductor arrays comprising means for compensating for heat loss to the surrounding formation by increasing field concentration at extremities of the heated volume to be recovered.

6. The apparatus of claim 5 wherein the conductors of the central conductor array are excited out of phase with the conductors of the upper and lower conductor arrays.

7. The apparatus of claim 6 wherein the conductors of each array are spaced a distance of less than one quarter of the wavelength of the electrical signal;

8. The apparatus of claim 7 wherein the spacing between the central conductor array and the upper conductor array is a distance d₁, which is less than one quarter of the wavelength of the electrical signal.

9. The apparatus of claim 8 wherein the spacing between the central conductor array and the lower conductor array is a distance d₂, which is less than one quarter of the wavelength of the electrical signal repressed thereon.

10. The apparatus of claim 9 wherein the horizontal width of the central conductor array is larger than that of upper and lower conductor arrays.

11. The apparatus of claim 10 wherein the distance d₂ is greater than the distance d₁, and wherein the horizontal width of the lower conductor array is larger than that of the upper conductor array, whereby, compensation is provided for heat loss to the surrounding formation due to downward fluid migration.

12. An apparatus for in situ heating of a volume of a hydrocarbonaceous formation to convert kerogen therein to recoerable oil and gas comprising:

electrical excitation means for providing an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz; and

an unbalanced transion line comprising;

a first conductor array located in the formation adjacent the surface of said volume and, electrically connected to said excitation means; and

a second conductor array having at least one conductor near the surface of said volume and at least one conductor in the interior of said volume;

conductors of said arrays and said excitation means comprising means for providing a relatively greater concentration of field intensity about conductors adjacent the surface of said volume to compensate for heat loss to the formation surrounding said volume.

13. An apparatus for in situ heating of a volume of a hydrocarbonaceous formation comprising:

means for generating an electrical signal of a frequency in the range of from 100 kilohertz to 100 megahertz;

a first array of one or more elongated conductors selectively inserted in a first outer row of boreholes penetrating the formation, adjacent elongated conductors being separated by a distance less than 1/4 of the wavelength of the electrical signal;

a second array of one or more elongated conductors selectively inserted in a second outer row of boreholes penetrating the formation, adjacent boreholes being separated by a distance less than 1/4 of the wavelength of the electrical signal, said second array being parallel to and spaced from said first array of conductors;

a third array of one or more conductors selectively inserted in a central row of boreholes penetrating the formation, adjacent conductors being separated by a distance less than 1/4 of the wavelength of the electrical signal, said third array being parallel to and spaced between said first and second arrays of conductors;

means for applying said electrical signal to the conductors of the arrays to heat approximately cylindrical volumes in the formation and to provide a concentration of field intensity about at least some of the conductors near the surface of said cylindrical volumes to compensate for heat loss to the formation surrounding said volume.