Temperature limited heater with a conduit substantially electrically isolated from the formation

• US 20080017370A1
• Filed: 10/20/2006
• Published: 01/24/2008
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Vinegar, Harold, Sandberg, Chester
• Granted Patent: US 7,559,367 B2
• Time in Patent Office: Days
• US Class Current: 166/248
• CPC Class Codes: C10G 1/002 in combination with oil conversion- or refining processes
• CPC Class Codes: C10G 1/02 by distillation
• CPC Class Codes: C10G 2300/308 Gravity, density, e.g. API
• CPC Class Codes: C10G 9/24 by heating with electrical means
• CPC Class Codes: E21B 43/24 using heat, e.g. steam injection
• CPC Class Codes: E21B 43/2401 by means of electricity
• CPC Class Codes: E21B 43/281 using heat
• CPC Class Codes: E21B 43/34 Arrangements for separating materials produced by the well
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]

Abstract

A system for heating a hydrocarbon containing formation is described. A conduit may be located in an opening in the formation. The conduit includes ferromagnetic material. An electrical conductor is positioned inside the conduit, and is electrically coupled to the conduit at or near an end portion of the conduit so that the electrical conductor and the conduit are electrically coupled in series. Electrical current flows in the electrical conductor in a substantially opposite direction to electrical current flow in the conduit during application of electrical current to the system. The flow of electrons is substantially confined to the inside of the conduit by the electromagnetic field generated from electrical current flow in the electrical conductor so that the outside surface of the conduit is at or near substantially zero potential at 25° C. The conduit may generate heat and heat the formation during application of electrical current.

Claims

1-895. -895. (canceled)

896. A system for heating a hydrocarbon containing formation, comprising:

a conduit located in an opening in the formation, the conduit comprising ferromagnetic material;

an electrical conductor positioned inside the conduit, and electrically coupled to the conduit at or near an end portion of the conduit so that the electrical conductor and the conduit are electrically coupled in series and electrical current flows in the electrical conductor in a substantially opposite direction to electrical current flow in the conduit during application of electrical current to the system;

wherein, during application of electrical current to the system, the flow of electrons is substantially confined to the inside of the conduit by the electromagnetic field generated from electrical current flow in the electrical conductor so that the outside surface of the conduit is at or near substantially zero potential at 25°

C.; and

the conduit is configured to generate heat and heat the formation during application of electrical current to the system.

897. The system of claim 896, wherein the outside of the conduit is substantially electrically isolated from the formation.

898. The system of claim 896, wherein the conduit is proximate the formation.

899. The system of claim 896, wherein the conduit is proximate the formation such that heat generated in the conduit wall transfers to the formation.

900. The system of claim 896, wherein the conduit is configured to generate a majority of the heat output of the system.

901. The system of claim 896, wherein the conduit has an outer circumference that is greater than an outer circumference of the electrical conductor, and heat generated in the conduit wall transfers from the outer circumference of the conduit to the formation.

902. The system of claim 896, wherein the conduit has a wall thickness of at least one skin depth of the ferromagnetic material at 25°

C.

903. The system of claim 896, wherein the conduit is electrically isolated from at least one adjacent conduit located in the formation.

904. The system of claim 896, wherein the opening has a first end portion at a first location on the surface of the formation and a second end portion at a second location on the surface of the formation.

905. The system of claim 896, wherein a majority of the conduit is oriented substantially horizontally in a hydrocarbon layer of the formation.

906. The system of claim 896, wherein the electrical conductor is substantially electrically isolated from the conduit along a length of the conduit, and the electrical conductor is electrically coupled to the conduit near an end portion of the conduit.

907. The system of claim 896, wherein the system further comprises one or more centralizers to electrically separate the conduit from the electrical conductor.

908. The system of claim 896, wherein the system further comprises a thin electrically insulating layer on a surface of the conduit and/or on the outside surface of the electrical conductor.

909. The system of claim 896, wherein the conduit is configured to provide a first heat output below the Curie temperature of the ferromagnetic member, the conduit being configured to automatically provide a second heat output approximately at and above the Curie temperature of the ferromagnetic member, and the second heat output is reduced compared to the first heat output.

910. The system of claim 896, wherein the electrical conductor is an insulated conductor, the insulated conductor including an electrically conductive core inside an electrically conductive sheath with electrical insulation between the core and the sheath.

911. The system of claim 910, wherein the core is copper and the sheath is non-ferromagnetic stainless steel.

912. The system of claim 896, wherein the system has a turndown ratio of at least 2 to 1.

913. The system of claim 896, wherein the conduit has a length of at least 500 m and is in a hydrocarbon layer of the formation.

914. The system of claim 896, wherein the conduit is configured to allow a fluid to flow through the conduit to preheat the conduit and the system.

915. The system of claim 896, wherein the conduit is configured to allow a fluid to flow through the conduit to recover heat from the system.

916. The system of claim 896, wherein the electrical conductor is a tubular conductor with openings at or near an end portion of the electrical conductor, the openings being configured to allow a fluid to flow between the inside of the electrical conductor and the conduit.

917. A method of heating a subsurface formation, comprising:

providing a conduit to an opening in the formation, wherein the conduit comprises ferromagnetic material;

positioning an electrical conductor inside the conduit;

providing the conduit so that the conduit is electrically coupled at or near an end portion of the conduit so that the electrical conductor and the conduit are electrically coupled in series and electrical current flows in the electrical conductor in a substantially opposite direction to electrical current flow in the conduit during application of electrical current to the system;

applying electrical current to the conduit to generate heat in the conduit, wherein, during application of electrical current, the flow of electrons is substantially confined to the inside of the conduit by the electromagnetic field generated from electrical current flow in the electrical conductor so that the outside surface of the conduit is at or near substantially zero potential at 25°

C.; and

allowing heat to transfer from the conduit to at least a portion of the formation.

918. The method of claim 917, wherein the subsurface formation comprises hydrocarbons, the method further comprising allowing the heat to transfer to the formation such that at least some hydrocarbons are pyrolyzed in the formation.

919. The method of claim 917, further comprising providing a hot heat transfer fluid to the conduit to provide heat to the formation.

920. The method of claim 919, wherein the hot heat transfer fluid comprises heated water, steam, and/or heated carbon dioxide.

921. The method of claim 917, further comprising producing a fluid from the formation.

922. The method of claim 917, further comprising providing a fluid to the conduit to recover heat from the system.

923. The method of claim 917, further comprising unspooling the conduit and the electrical conductor from one or more spools.

924. The method of claim 917, further comprising substantially electrically isolating the outside of the conduit from the formation.

925. The method of claim 917, wherein the conduit is provided to the opening such that a majority of the heat output is generated in the conduit wall, and such heat output transfers to the formation.

926. A transportation fuel made by a method, comprising:

providing a conduit to an opening in the formation, wherein the conduit comprises ferromagnetic material;

positioning an electrical conductor inside the conduit;

providing the conduit so that the conduit is electrically coupled at or near an end portion of the conduit so that the electrical conductor and the conduit are electrically coupled in series and electrical current flows in the electrical conductor in a substantially opposite direction to electrical current flow in the conduit during application of electrical current to the system;

applying electrical current to the conduit to generate heat in the conduit, wherein, during application of electrical current, the flow of electrons is substantially confined to the inside of the conduit by the electromagnetic field generated from electrical current flow in the electrical conductor so that the outside surface of the conduit is at or near substantially zero potential at 25°

C.;

allowing heat to transfer from the conduit to at least a portion of the formation;

producing a fluid from the formation; and

producing the transportation fuel from at least some of the produced fluid.

927-1559. -1559. (canceled)