# US 2009/0260833 A1 · Method and Apparatus to Provide Electrical Connection in a Wellhead for a Downhole Electrical Device

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- Number: US 2009/0260833 A1
- Document ID: US20090260833A1
- Status: Published application
- Kind: A1
- Application number: 12/493,697
- Filed: 2009-06-29
- Published: 2009-10-22
- Earliest claimed: 2003-08-05
- Assignees: Stream-Flo Industries Ltd.
- Inventors: Abram Khazanovich; Irina Khazanovich; Nathan Kwasniewski
- Web page: https://patentgrep.com/patent/US20090260833A1

## CPC

- E21B 33/0385: {electrical connectors}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

Wellhead assembly and method for providing a power connection to a downhole electrical device, such as a heater. Pressure-containing wellhead body members enclose a vertical wellbore and support therein an isolated tubing hanger and a grounding tubing hanger. The isolated tubing hanger suspends a conducting tubing string, while the grounding tubing hanger suspends a grounding tubing string concentrically spaced from the conducting tubing string. The isolated tubing hanger has an outer housing, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection with, and suspend, the conducting tubing string, and insulation between the housing and conducting portion to electrically isolate the housing portion. Hot electrical connection is made for electrical connection to the conducting portion of the isolated tubing hanger or the conducting tubing string. Electrical isolation seals and electrically isolates the hot electrical connection from the wellhead body members. Grounding connection is provided to a wellhead body member. A source of current provides a first connection to the hot electrical connection and a second connection to the grounding connection.

## Claims

### Claim 1

A wellhead assembly for providing a power connection to a downhole electrical device, comprising:
a. one or more pressure-containing wellhead body members enclosing a vertical wellbore extending there through, the one or more body members supporting, in sealed relationship in the vertical wellbore, an isolated tubing hanger and a grounding tubing hanger, the isolated tubing hanger suspending therefrom a conducting tubing string, and the grounding tubing hanger suspending therefrom a grounding tubing string concentrically spaced from the conducting tubing string, both of the tubing strings being electrically conductive and electrically connected to the downhole electrical device;
b. the isolated tubing hanger having an outer housing which seats in the vertical wellbore of one of the one or more wellhead members, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection to, and suspend, the conducting tubing string, and insulation between the housing and the conducting portion to electrically isolate the housing portion from the conducting portion;
c. a hot electrical connection for making an electrical connection to the conducting tubing string or to the conducting portion of the isolated tubing hanger;
d. electrical isolation associated with the hot electrical connection and the one or more wellhead body members for sealing and electrically isolating the hot electrical connection such that the one or more wellhead body members remain electrically isolated from the hot electrical connection;
e. a grounding connection connected to the one or more wellhead body members for making a ground connection to the grounding tubing string; and
f. a source of current having a first connection to the hot electrical connection and a second connection to the grounding connection.

### Claim 2 (depends on 1)

The assembly as set forth in claim 1, wherein:
the one or more body members form separate first and second tubing hanger profiles in the vertical wellbore to support and seat the grounding tubing hanger and the isolated tubing hanger in vertically stacked relationship in the vertical wellbore.

### Claim 3 (depends on 2)

The assembly as set forth in claim 2, wherein:
the conducting portion of the isolated tubing hanger includes a conducting neck portion extending upwardly above the outer housing of the isolated tubing hanger; and
the hot electrical connection connects to the conducting neck portion outside the vertical wellbore.

### Claim 4 (depends on 3)

The assembly as set forth in claim 3, wherein the hot electrical connection includes a conductive clamp assembly connected to the first connection of the source of current, said clamp assembly being operative to clamp onto the conducting neck portion of the isolated tubing hanger for electrical connection outside the vertical wellbore.

### Claim 5 (depends on 4)

The assembly as set forth in claim 4, wherein the isolated tubing hanger is located vertically above the grounding tubing hanger, and wherein the conducting tubing string suspended from the isolated tubing hanger is the inner of the concentrically arranged tubing strings.

### Claim 6 (depends on 5)

The assembly as set forth in claim 5, wherein the one or more wellhead body members includes a tubing head operative to support the isolated tubing hanger, and a tubing head adapter connected and sealed above the tubing head, such that the conducting neck portion of the isolated tubing hanger extends upwardly through the tubing head adapter and ends outside the vertical wellbore for electrical connection, and wherein the electrical isolation extends through vertical wellbore in the tubing head adapter to electrically isolate and seal the conducting neck portion of the isolated tubing hanger in the vertical wellbore.

### Claim 7 (depends on 6)

The assembly as set forth in claim 6, wherein:
the clamp assembly clamps onto the conducting neck portion of the isolated tubing hanger outside the vertical wellbore in an isolated electrical junction box mounted above the tubing head adapter;
the assembly further includes a retainer ring fastened around the conducting neck portion of the isolated tubing hanger at the top of the tubing head adapter; and
the electrical isolation includes:
I. upper and lower load supporting insulating rings around the conducting neck portion of the isolated tubing hanger;
ii. packing rings between the upper and lower insulating rings to seal the conducting neck portion in the vertical bore of the tubing head adapter; and
iii. an insulating sleeve, separate from or integral with, the upper insulating ring around the conducting neck portion and extending through the retainer ring above the tubing head adapter such that the retainer ring retains the electrical isolation to seal the vertical wellbore through the tubing head adapter.

### Claim 8 (depends on 7)

The assembly as set forth in claim 7, wherein the one or more of the insulating sleeve, upper and lower insulating rings and packing rings slide together in an overlapping manner to increase creepage gap and improve electrical isolation.

### Claim 9 (depends on 8)

The assembly as set for in claim 8, where the packing rings include a plurality of stacked inner and outer V-rings separated by a downwardly extending circular rim on the upper insulating ring, and wherein the circular rim fits into a circular groove on the lower insulating ring, such that fastening of the retainer ring onto the tubing head adapter retains the upper and lower insulating rings and the packing rings in a manner to seal the vertical wellbore and the conducting neck portion of the isolated tubing hanger.

### Claim 10 (depends on 6)

The assembly as set forth in claim 6, wherein the one or more wellhead body members further comprises a separate grounding tubing head connected below the tubing head for the isolated tubing hanger, the grounding tubing head being operative to support the grounding tubing hanger, and the grounding connection being made to the tubing head adapter.

### Claim 11 (depends on 9)

The assembly as set forth in claim 9, wherein the one or more wellhead body members further comprises a separate grounding tubing head connected below the tubing head for the isolated tubing hanger, the grounding tubing head being operative to support the grounding tubing hanger, and the grounding connection being made to the tubing head adapter.

### Claim 12

A hot electrical connection assembly in a wellhead for providing a power connection to a tubing string extending to a downhole electrical device, comprising:
a. one or more pressure-containing wellhead body members enclosing a vertical wellbore extending there through, the one or more body members supporting, in sealed relationship in the vertical wellbore, an isolated tubing hanger, the isolated tubing hanger suspending therefrom a conducting tubing string electrically connected to the downhole electrical device;
b. the isolated tubing hanger having an outer housing which seats in the vertical wellbore of the one of the one or more wellhead members, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection to, and suspend, the conducting tubing string, and insulation between the housing and the conducting portion to electrically isolate the housing portion from the conducting portion;
c. a hot electrical connection for making an electrical connection to the conducting tubing string or to the conducting portion of the isolated tubing hanger; and
d. electrical isolation associated with the hot electrical connection and the one or more wellhead members for sealing and electrically isolating the hot electrical connection such that the one or more wellhead body members remain electrically isolated from the hot electrical connection.

### Claim 13 (depends on 12)

The hot electrical connection assembly as set forth in claim 12, wherein:
the one or more body members form a tubing hanger profile in the vertical wellbore to support and seat the isolated tubing hanger; and
the conducting portion of the isolated tubing hanger includes a conducting neck portion extending upwardly above the outer housing of the isolated tubing hanger; and
the hot electrical connection connects to the conducting neck portion outside the vertical wellbore.

### Claim 14 (depends on 13)

The hot electrical connection assembly as set forth in claim 13, wherein the hot electrical connection includes a conductive clamp assembly connected to the conducting neck portion of the isolated tubing hanger for electrical connection outside the vertical wellbore.

### Claim 15 (depends on 14)

The hot electrical connection assembly as set forth in claim 14, wherein the one or more wellhead body members includes a tubing head operative to support the isolated tubing hanger, and a tubing head adapter connected and sealed above the tubing head, such that the conducting neck portion of the isolated tubing hanger extends upwardly through the tubing head adapter and ends outside the vertical wellbore for electrical connection, and wherein the electrical isolation extends through vertical bore in the tubing head adapter to isolate and seal the conducting neck portion of the isolated tubing hanger in the vertical bore.

### Claim 16 (depends on 15)

The hot electrical connection assembly as set forth in claim 15, wherein:
the clamp assembly clamps onto the conducting neck portion of the isolated tubing hanger outside the vertical wellbore in an isolated electrical junction box mounted above the tubing head adapter;
the assembly further includes a retainer ring fastened around the conducting neck portion of the isolated tubing hanger at the top of the tubing head adapter; and
the electrical isolation includes:
I. upper and lower load supporting insulating rings around the conducting neck portion of the isolated tubing hanger;
ii. packing rings between the upper and lower insulating rings to seal the conducting neck portion in the vertical bore of the tubing head adapter; and
iii. an insulating sleeve, separate from or integral with, the upper insulating ring around the conducting neck portion and extending through the retainer ring above the tubing head adapter such that the retainer ring retains the electrical isolation to seal the vertical wellbore through the tubing head adapter.

### Claim 17 (depends on 16)

The hot electrical connection assembly as set forth in claim 16, wherein one or more of the insulating sleeve, upper and lower insulating rings and packing rings slide together in an overlapping manner to increase gap and improve electrical isolation.

### Claim 18 (depends on 17)

The hot electrical connection assembly as set for in claim 17, where the packing rings include a plurality of stacked inner and outer V-rings separated by a downwardly extending circular rim on the upper insulating ring, and wherein the circular rim fits into a circular groove on the lower insulating ring, such that fastening of the retainer ring onto the tubing head adapter retains the upper and lower insulating rings and packing rings in a manner to seal the vertical wellbore and the conducting neck portion of the isolated tubing hanger.

### Claim 19

An isolated tubing hanger for suspending a conducting tubing string within a pressure-containing tubing head, the isolated tubing hanger comprising:
a. an outer housing which seats in the tubing head, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection to, and suspend, the conducting tubing string, and insulation between the housing and the conducting portion to electrically isolate the housing portion from the conducting portion;
b. the housing forming a central bore with an inwardly extending circumferential landing seat at its lower end, and carrying outer circumferential seals to seal with the tubing head;
c. the conducting portion of the isolated tubing hanger including a landing shoulder to seat on the landing seat, and a conducting neck portion connected to, or integral with, the conducting portion extending upwardly relative to the housing, said conducting neck portion providing the electrical connection to the conducting tubing string;
d. the insulation including load supporting insulation plates located above and below the landing shoulder, and a plurality of insulation sleeves between the housing and the conducting portion;
e. one or more seals between the landing shoulder and the landing seat to seal the conducting portion of the isolated tubing hanger with the housing; and
f. a retainer ring at the top of the housing around the conducting neck portion to retain, seal and energize the insulation and the one or more seals.

### Claim 20 (depends on 19)

The isolated tubing hanger as set forth in claim 19, wherein the insulation plates and the insulation sleeves are threaded together to increase creepage gap and electrical isolation.

### Claim 21

A method for providing a power connection from a source of current located at a wellhead to a downhole electrical device, wherein the wellhead includes one or more pressure-containing wellhead body members forming a vertical wellbore extending there through, the one or more wellhead body members being operative to support, in sealed relationship in the vertical wellbore, a first and a second tubing hanger, each tubing hanger being operative to suspend therefrom a tubing string such that a first and a second tubing string are concentrically spaced from each other, the method comprising:
a. providing electrical isolation to the first of the tubing hangers such that an outer housing of the first tubing hanger is electrically isolated from an inner, electrically conducting portion of the first tubing hanger;
b. suspending the first tubing string from the electrically conducting portion of the first tubing hanger;
c. providing insulation between the outer housing and the inner conducting portion of the first tubing hanger to electrically isolate the outer housing portion from the inner conducting portion;
d. connecting the source of current in a sealed and electrically isolated manner to the inner electrically conducting portion of the first tubing hanger or to the first tubing string, such that the one or more wellhead members are electrically isolated from the first tubing string; and
e. connecting the source of current to the one or more wellhead body members so as to provide a grounding connection to the second tubing string.

### Claim 22 (depends on 21)

The method as set forth in claim 21, wherein:
the one or more wellhead body members form first and second tubing hanger profiles in the vertical wellbore to support and seat the first and second tubing hangers in vertically stacked relationship in the vertical wellbore; and
the inner conducting portion of the first tubing hanger includes a conducting neck portion extending upwardly above the outer housing of the first tubing hanger; and
the source of current is connected to the conducting neck portion outside the vertical wellbore.

### Claim 23 (depends on 22)

The method as set forth in claim 22, wherein the source of current is connected to the conducting neck portion by an electrically conductive clamp clamped to the conducting neck portion of the first tubing hanger outside the vertical wellbore.

### Claim 24 (depends on 21)

The method as set forth in claim 21, wherein the source of current is connected to the conducting neck portion by an electrically conductive clamp clamped to the conducting neck portion of the first tubing hanger outside the vertical wellbore.

### Claim 25 (depends on 1)

The assembly as set forth in claim 1, wherein the conducting portion of the isolated tubing hanger includes a conducting neck portion extending upwardly or downwardly above or below the outer housing of the isolated tubing hanger, said conducting neck portion providing electrical connection to the conducting tubing string.

### Claim 26 (depends on 25)

The assembly as set forth in claim 25, wherein the hot electrical connection includes a conductive rod connected at one end to the first connection of the source of current, and at the other end to a clamp assembly, said clamp assembly being operative to clamp together, for electrical connection within the vertical wellbore, the conductive rod and the neck portion of the isolated tubing hanger, and wherein both the conductive rod and the clamp assembly are formed of electrically conductive materials.

### Claim 27 (depends on 26)

The assembly as set forth in claim 26, wherein the isolated tubing hanger is located vertically above the grounding tubing hanger, wherein the conducting tubing string suspended from the isolated tubing hanger is the inner of the concentrically arranged tubing strings, and wherein the conducting neck portion of the isolated tubing hanger is upwardly extending within the vertical wellbore.

### Claim 28 (depends on 27)

The assembly as set forth in claim 27, wherein the one or more wellhead body members forms a receptacle in its wall proximate the grounding tubing hanger, and wherein the grounding connection includes a grounding rod having one end extending into the receptacle and the other end connected to the grounding connection.

### Claim 29 (depends on 12)

The hot electrical connection assembly as set forth in claim 12, wherein:
the one or more wellhead body members forms a conduit to provide access to the vertical wellbore proximate the isolated tubing hanger for electrical connection to the conducting tubing string;
the hot electrical connection extends through the conduit for making an electrical connection through to the conducting tubing string or to the conducting portion of the isolated tubing hanger, said hot electrical connection including a conductive rod connected at one end to a source of current, and at the other end to a conducting clamp assembly, said clamp assembly being operative to clamp together, for electrical connection within the vertical wellbore, the conductive rod and either the conducting tubing string or the conducting portion of the isolated tubing hanger; and
the electrical isolation is associated with the hot electrical connection for sealing and electrically isolating the hot electrical connection in the conduit such that the one or more wellhead body members remain electrically isolated.

### Claim 30 (depends on 29)

The hot electrical connection assembly of claim 29, wherein the conducting portion of the isolated tubing hanger includes an upwardly extending neck portion above the outer housing of the isolated tubing hanger, said neck portion being the portion of the isolated tubing hanger which is clamped by the clamp assembly to the conductive rod.

### Claim 31 (depends on 12)

The hot electrical connection assembly as set forth in claim 12, wherein:
the one or more wellhead body members forms a conduit to provide access to the vertical wellbore proximate the isolated tubing hanger for electrical connection to the conducting tubing string;
the hot electrical connection extends through the conduit for making an electrical connection through to the conducting tubing string in the vertical wellbore, the hot electrical connection including at least one reciprocating horizontal ram in the conduit, the ram having a conductive rod end connected to a source of current and a ram end to make the electrical connection to the conducting tubing string when in an extended position, and to break the electrical connection when in a retracted position; and
the electrical isolation is associated with the hot electrical connection for sealing and electrically isolating the hot electrical connection in the conduit such that the one or more wellhead body members remain electrically isolated.

### Claim 32 (depends on 31)

The hot electrical connection assembly as set forth in claim 31, wherein the one or more wellhead body members includes a separate tubing head to support and seat the isolated tubing hanger in the vertical wellbore, and wherein the conducting portion of the isolated tubing hanger includes a conducting neck portion extending downwardly below the housing of the isolated tubing hanger, said conducting neck portion providing the electrical connection to the horizontal ram.

### Claim 33 (depends on 21)

The method as set forth in claim 21, further comprising:
the one or more wellhead body members forming a first and a second tubing hanger profile in the vertical wellbore to support and seat the first and second tubing hangers in vertically stacked relationship in the vertical wellbore;
providing a conduit in the one or more wellhead body members to provide access to the vertical bore proximate the first tubing hanger; and
connecting the source of current through the conduit in a sealed and electrically isolated manner to the electrically conducting portion of the first tubing hanger or to first tubing string, such that the one or more wellhead members are electrically isolated from the first tubing string.

### Claim 34 (depends on 33)

The method as set forth in claim 33, wherein:
the electrically conducting portion of the first tubing hanger includes a conducting neck portion extending upwardly above the outer housing of the first tubing hanger; and
the source of current is connected to the conducting neck portion in the vertical wellbore.

### Claim 35 (depends on 34)

The method as set forth in claim 34, wherein the source of current is connected to the conducting neck portion by an electrically conductive clamp clamped to the conducting neck portion of the first tubing hanger in the vertical wellbore.

### Claim 36 (depends on 35)

The method as set forth in claim 35, wherein the source of current is connected to the one or more wellhead body members at a location proximate the second tubing hanger to provide the grounding connection to the second tubing string.