Electrical connection

Details Electrical connection Electrical connection

1998-07-16

2001-03-13

Abrams, Neil (Department: 2839)

Electrical connectors

With coupling movement-actuating means or retaining means in...

Retaining means with distinct movement-actuating means to...

Reexamination Certificate

active

06200152

ABSTRACT:

DESCRIPTION OF THE RELATED ART
Electrical connections are required in housing assemblies for high power circuits for running downhole equipment such as pumps and heating coils, and for electrical signals to and from downhole equipment. Such electrical connections are conventionally made through the top of the tubing hanger once the tubing hanger is landed in a housing or wellhead. The space available for the connections is therefore limited. This may result in the production bore being off-centre which has serious operational implications in ensuring equipment is correctly aligned. Furthermore, the blow out preventer has to be removed for access to the top of the tubing hanger. The tubing hanger then provides the only barrier, which causes a safety problem if the well is live.
The electrical connection must pass through a pressure boundary to the tubing hanger. In the case of a power core, full insulation is needed. As good insulators have generally poor sealing properties, sealing at the pressure boundary at the well temperature is difficult.
According to the present invention, an assembly providing an electrical connection across an interface between a radially inner member and a surrounding radially outer member, comprises a sealed enclosure between the inner and outer members; a cable which leads to the enclosure and is fixed and sealed to a wall of the enclosure, and which has at least one conducting core; an electrical coupling element within the inner member; and a shuttle which is reciprocatable radially inwardly from a disconnected position wholly within the outer member to a connected position in which the shuttle makes an electrical connection from the conductor core to the electrical coupling element.
As the connection is made across a peripheral surface in a radial plane, it does not have to be through the top of the inner member, e.g. a tubing hanger. Therefore the space limitation of the prior art is avoided. Furthermore, when the invention is applied to the housing of a wellhead assembly, it eliminates the need to remove the blow out preventer.
It is the shuttle which bridges the gap across the enclosure between the inner and outer members and therefore prevents damage to the cable which is not exposed in the potentially hostile pressurised region between the two members. No electrical cables or components are required to move through a pressure barrier so that make up can be achieved in a constant volume void irrespective of the pressure.
As the shuttle does not have to contain pressure, there is no problem achieving an insulated connection.
In one embodiment, generally suitable for an electrical signal, a connecting cable connected to the cable is coiled within the enclosure and is fixed to the shuttle. The connecting cable may be an extension of the cable core. When the electrical connection is made up, the coil is simply extended.
SUMMARY OF THE INVENTION
Such flexible coiled cables are not practical for making electrical connections for power supplies. Therefore, as an alternative, the shuttle is slidable with respect to a fixed power core which provides a coupling element electrically connected to the cable core. Thus, only the shuttle is moved. The shuttle may be provided at either or both ends with a pin which mates with a corresponding socket of the respective coupling element to make the electrical connections, or the shuttle may be provided at either or both ends with a socket which mates with a corresponding pin of the respective coupling element to make the electrical connections.
For a large concentric production bore, the invention maybe used in the housing of a wellhead assembly in which a plurality of connections are circumferentially disposed about the longitudinal axis of the tubing hanger, and have their lines of operation offset from the axis of the tubing hanger. For three phase power, three separate connections can be used. Preferably the lines of operation are tangential to a circle centred on the axis of the tubing hanger.
The space within the shuttle may be filled with a dielectric gel which is contained within a flexible bladder exposed to the surrounding pressure. This ensures that the pressure inside the shuttle remains constant with respect to the surrounding pressure and prevents any ingress of hostile fluids that could contaminate the gel. A series of gland type diaphragms may be provided at each end of the shuttle which seal with the respective coupling element, or close up in the absence of a coupling element in order to retain the gel within the shuttle. The complete sealing allows the connection to be made up under pressure.
The shuttle may be reciprocated by rotation of a screw threaded element coupled to the shuttle.
As an alternative to providing a plurality of connections circumferentially disposed about the axis of the tubing hanger, a plurality of cables may be connected in a single connection. In this case, there may be insufficient room in the wall of the tubing hanger to accommodate a set of single 90° couplings around a concentric bore. It may therefore be necessary to offset the bore of the tubing hanger from the axis of the tubing hanger.
This arrangement means that only one diver or ROV operation is necessary to make several connections, thereby reducing the time taken, and hence the costs. Furthermore the cable does not have to be separated and then spliced together down the well.
One particularly advantageous way of offsetting the bore is to provide an axial bore in the top of the tubing hanger, which bore leads into an offset bore having a diameter smaller than that of the axial bore allowing a tubing string to be supported with its axial offset from the axis of the tubing hanger. This has the advantage that operations associated with the top of the tubing hanger, such as running tool operations, can still be performed in concentric mode. Furthermore, double barrier protection can be provided in the form of two concentric plugs in the axial bore. This means a BOP can be installed prior to the removal of the plugs, allowing safe access to a live well irrespective of its condition of completion.
This offset bore configuration provides an independent invention as it can be used in any application where more space is required at one side of the tubing hanger wall.


REFERENCES:
patent: 3638732 (1972-02-01), Huntsinger et al.
patent: 4289199 (1981-09-01), McGee
patent: 4491176 (1985-01-01), Reed
patent: 4795359 (1989-01-01), Alcock et al.
patent: 4859196 (1989-08-01), Durando et al.
patent: 5443328 (1995-08-01), Alcock et al.
patent: 2059081 (1971-06-01), None
patent: 0251655 (1988-01-01), None
patent: 0493375 (1992-07-01), None
patent: 2166775 (1987-05-01), None
patent: 8601852 (1986-03-01), None
patent: 8603799 (1986-07-01), None
patent: 9200438 (1992-01-01), None
SPE 23050Electrical Submersible Pumps in Subsea Completions; Sep. 3-6, 1991; P.A. Scott, M. Bowring, B. Coleman.
Offshore Technology Conference (OTC 5887) Deepwater Christmas Tree Development; P.P. Alfano, C.H.N. Barbosa, M.A. Lewis; May 1-4, 1989; (pp. 57-65).
Offshore Technology Conference (OTC 7065); A High-Voltage System for Subsea Electrical Submersible Pumping; Neil Duncan, P.A. Scott, E.R. Schweim,; May 4-7, 1992; (pp. 701-705).
Subsea Intervention Systems Ltd.;Subsea Applications for Downhole Pumping; M. Bowring, et al; DOT 1991; (pp. 71-78).
Concentric Tubing Hanger Designs for BP's Universal Subsea Wellhead; H.P. Hopper; undated.
Cooper Oil Tool;Phillips Petroleum Company Ann Subsea Facility; TMH0445, Nov. 1991; (pp. CCH 36064-36223).
SISL Subsea Submersible Pumping (S.S.P.),Second Interim Report—Technical Jun. 1991, Project No. TH/03328/89; Projects of Technological Development in the Hydrocarbons Sector(Regulation EEC 3639/85; KAS 10837-10970; Jun. 1991.
Framo Engineering: Drawings of ESP Subsea System; (2 pages); undated.
Document No. SSP-020-021; Subsea Intervention Systems Ltd.;Subsea Submersible Pumping Project; Final Report vols. 1, 2 and 3; (pp. KAS10024-KAS10678); Mar. 1992.
Cooper Oil Tool;Phillips Petroleum Company Ann Subsea

Affiliated with

Also associated with

Rating

Electrical connection does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electrical connection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical connection will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2508693