Inductive coupler for well tools

Claim 2

An induction coupler for use with coaxial arranged tubular members comprising: A first tubular member constructed from like non-magnetic material and having a wall defining an cylindrically shaped inner core enclosure; a core assembly disposed in said core enclosure and including a cylindrically shaped central magnetic ferrite rod, a central member with a thin wall central section forming a bore which is disposed about said ferrite rod and cylindrically shaped end pieces located at the ends of said ferrite rod, said central member having at least one lengthwise extending, thin separation defining lengthwise extending facing surfaces and an electrical insulation separating the adjoining facing surfaces, and a wire coil wrapped about said central section, said central member being constructed from a magnetic material; said wall of said tubular member having a defined first wall thickness; a second tubular member constructed from like non-magnetic materials and having inner and outer walls defining an annular shaped outer enclosure with the inner wall having a defined second wall thickness; said first tubular member being sized relative to said second tubular member in a co-axial arrangement to define an annular spacing with a gap spacing between the outer surface of said wall of said first tubular member and the inner surface of said inner wall where said gap spacing, said first wall thickness and said second wall thickness effectively define the magnetic air gap; and an annular coil assembly in said annular shaped outer enclosure including a wire coil wrapped around the inner wall and two annular end pieces located at the ends of the annular coil assembly, said end pieces having at least one lengthwise extending thin separation defining spacing surfaces, and an electrical insulation separating the adjoining facing surfaces, and a magnetic coupling means extending between said end pieces.

Claim 3

The coupler as set forth in claim 1 wherein the second wall thickness and the first wall thickness are relatively large as compared to the width of the gap spacing.

Claim 4

The coupler as set forth in claim 2 wherein the ratio of the gap spacing to the combined dimensions of the wall thicknesses and gap spacing is 1 to 9 or greater.

Claim 5

The coupler as set forth in claim 2 and further including guide means on said tubular members for assisting location of said first tubular member in said second tubular member.

Claim 6

The coupler as set forth in claim 4 wherein said guide means includes a beveled surface on one of said members and a beveled surface on the other of said members.

Claim 7

The coupler as set forth in claim 1 wherein said electrical insulation is a relatively thin coating material.

Claim 8

The coupler as set forth in claim 1 wherein said magnetic coupling means is magnetic tape wound about the coil.

Claim 9

The coupler as set forth in claim 1 wherein the non-magnetic materials are corrosion resistant.

Claim 10

The coupler as set forth in claim 1 wherein said central member is formed from complimentary semi-cylindrical elements to define two lengthwise extending thin separations defining lengthwise extending facing surfaces and electrical insulation separates the adjoining facing surfaces of said semi-cylindrical elements.

Claim 11

The coupler as set forth in claim 9 wherein said annular end pieces are semi-annular and thin electrical insulation is disposed between adjoining facing surfaces of said annular end pieces.

Claim 12

The coupler as set forth in claim 1 where there are more than one lengthwise extending, thin separations in said central member with thin electrical insulation separating adjoining facing surfaces at each separation.

Claim 13

The coupler as set forth in claim 11 wherein there are more than one thin lengthwise extending separations in said annular end pieces and electrical insulation is disposed between adjoining facing surfaces at a separation.

Claim 14

Apparatus for use in a well bore in a side pocket mandrel where said side pocket mandrel has a longitudinally extending side pocket bore offset from a longitudinally extending main bore of the mandrel for inductively coupling a well tool to an inductive probe, said apparatus comprising: an elongated probe housing disposed in said side pocket bore, said probe housing being a tubular member constructed from a non-magnetic material and having a housing wall defining a central bore for receiving a core assembly and a connecting end bore for receiving an electronics assembly, said core assembly including a cylindrically shaped central magnetic ferrite rod, a tubular shaped member formed by complementary semi-cylindrical shell members with a thin wall central section forming a bore which is disposed about said ferrite rod, and cylindrically shaped end pieces located at the ends of said ferrite rod, said shell member and having an electrical insulation adjoining facing surfaces, and a wire coil wrapped about said central section, and said shell members being constructed from a magnetic material, a well tool sized for passage through the main bore of the side pocket mandrel and sized for reception in the side pocket bore of the side pocket mandrel, said well tool having an annular end portion with tubular inner and outer members constructed from a non-magnetic material and where said inner member has a socket wall defining a bore sized to receive said probe housing and to define a gap spacing therebetween, said inner member having an outer annular recess, an annular coil wrapped around the inner member and two semi-annular end pieces made of magnetic material and located at the ends of the annular coil assembly, said end pieces having an electrical insulation separating adjoining facing surfaces, and a magnetic coupling means extending between said end pieces, said socket wall, said housing wall and said gap spacing being sized to minimize the gap spacing relative to the thickness of said walls and said socket wall and the housing wall having a thickness minimized to the minimum strength required for the mechanical performance of the tool and the probe housing.

Claim 15

Apparatus for use in a well bore in a side pocket mandrel where said side pocket mandrel has a longitudinally extending side pocket bore offset from a longitudinally extending main bore of the mandrel for inductively coupling a well tool to an inductive probe, said apparatus comprising: an elongated probe housing disposed in said side pocket bore, said probe housing being a tubular member constructed from a non-magnetic material and having a housing wall defining a central bore for receiving a core assembly and a connecting end bore for receiving an electronics assembly, said core assembly including a cylindrically shaped central magnetic ferrite rod, a tubular shaped member formed by complementary semi-cylindrical shell members with a thin wall central section forming a bore which is disposed about said ferrite rod, and cylindrically shaped end pieces located at the ends of said ferrite rod, said shell member and having an electrical insulation adjoining facing surfaces, and a wire coil wrapped about said central section, and said shell members being constructed from a magnetic material, a well tool sized for passage through the main bore of the side pocket mandrel and sized for reception in the side pocket bore of the side pocket mandrel, said well tool having an annular end portion with tubular inner and outer members constructed from a non-magnetic material and where said inner member has a socket wall defining a bore sized to receive said probe housing and to define a gap spacing therebetween, said inner member having an outer annular recess, an annular coil wrapped around the inner member and two semi-annular end pieces made of magnetic material and located at the ends of the annular coil assembly, said end pieces having an electrical insulation separating adjoining facing surfaces, and a magnetic coupling means extending between said end pieces, said socket wall, said housing wall and said gap spacing being sized to minimize the gap spacing relative to the thickness of said walls and said socket wall and the housing wall having a thickness minimized to the minimum strength required for the mechanical performance of the tool and the probe housing.

Claim 16

The apparatus as set forth in claim 13 and further including a nose piece adapted to fit into the central bore and attached thereto and an end piece adapted to fit into the end bore and attached thereto, said tubular member, said nose piece and said end piece being made from like non-magnetic materials.

Claim 17

The apparatus as set forth in claim 13 and further including a transverse ledge in said side pocket bore separating said side pocket bore into an upper tool pocket and a lower cable enclosure, said ledge having a seating surface; said probe housing having seating surface engaging the seating surface of the ledge, said probe housing further having an high pressure cable connector means disposed in said lower housing and adapted for coupling to a cable.

Claim 18

The apparatus as set forth in claim 15 wherein said seating surfaces are beveled for assisting the location of said well tool in said probe housing.

Claim 19

The apparatus as set forth in claim 13 wherein said shell members are constructed from soft magnetic iron.

Claim 20

The apparatus as set forth in claim 13 wherein said electrical insulation is a relatively thin coating material.

Claim 21

The apparatus as set forth in claim 13 wherein said magnetic coupling means is magnetic tape wound about the coil.

Claim 22

The apparatus as set forth in claim 13 wherein said non-magnetic materials are corrosion resistant.

Claim 23

The apparatus as set forth in claim 15 wherein an electronics assembly is located in said end bore and includes a square wave generator for generating power for said well tool and said well tool has a full wave rectifier for obtaining d.c. power to the well tool, said cable being connected to a surface located source of power.

Claim 24

The apparatus as set forth in claim 21 and further including frequency modulating means for encoding and decoding transmission of signals between said well tool and surface located equipment.

Claim 25

Apparatus for use in a well bore in a side pocket mandrel where said side pocket mandrel has a longitudinally extending side pocket bore offset from a longitudinally extending main bore of the mandrel for inductively coupling a well tool to an inductive probe, said apparatus comprising: an elongated probe housing disposed in said side pocket bore, said probe housing being a tubular member constructed from a non-magnetic material and having a housing wall defining a central bore for receiving a core assembly and a connecting end bore for receiving an electronics assembly, said core assembly including a cylindrically shaped central magnetic ferrite rod, a shell member with a thin wall central section forming a bore which is disposed about said ferrite rod, and cylindrically shaped end pieces located at the ends of said ferrite rod, said shell member having at least one lengthwise extending, thin separation defining facing surfaces, an electrical insulation separating the adjoining facing surfaces, and a wire coil wrapped about said central section, and said shell members being constructed from a magnetic material. a well tool sized for passage through the main bore of the side pocket mandrel and sized for reception in the side pocket bore of the side pocket mandrel, said well tool having an annular end portion with tubular inner and outer members constructed from a non-magnetic material and where said inner member has a socket wall defining a bore sized to receive said probe housing and to define a gap spacing therebetween, said inner member having an outer annular recess, an annular coil wrapped around the inner member and two end pieces made of magnetic material located at the ends of the annular coil assembly, said end pieces having at least one lengthwise extending thin separation defining facing surfaces, an electrical insulation separating the adjoining facing surfaces, and a magnetic coupling means extending between said end pieces, said socket wall, said housing wall and said gap spacing being sized to minimize the gap spacing relative to the thickness of said walls and said socket wall and the housing wall having a thickness minimized to the minimum strength required for the mechanical performance of the tool and the probe housing.

Claim 26

Apparatus for use in a well bore in a side pocket mandrel where said side pocket mandrel has a longitudinally extending side pocket bore offset from a longitudinally extending main bore of the mandrel for inductively coupling a well tool to an inductive probe, said apparatus comprising: an elongated probe housing disposed in said side pocket bore, said probe housing being a tubular member constructed from a non-magnetic material and having a housing wall defining a central bore for receiving a core assembly and a connecting end bore for receiving an electronics assembly, said core assembly including a cylindrically shaped central magnetic ferrite rod, a shell member with a thin wall central section forming a bore which is disposed about said ferrite rod, and cylindrically shaped end pieces located at the ends of said ferrite rod, said shell member having at least one lengthwise extending, thin separation defining facing surfaces, an electrical insulation separating the adjoining facing surfaces, and a wire coil wrapped about said central section, and said shell members being constructed from a magnetic material. a well tool sized for passage through the main bore of the side pocket mandrel and sized for reception in the side pocket bore of the side pocket mandrel, said well tool having an annular end portion with tubular inner and outer members constructed from a non-magnetic material and where said inner member has a socket wall defining a bore sized to receive said probe housing and to define a gap spacing therebetween, said inner member having an outer annular recess, an annular coil wrapped around the inner member and two end pieces made of magnetic material located at the ends of the annular coil assembly, said end pieces having at least one lengthwise extending thin separation defining facing surfaces, an electrical insulation separating the adjoining facing surfaces, and a magnetic coupling means extending between said end pieces, said socket wall, said housing wall and said gap spacing being sized to minimize the gap spacing relative to the thickness of said walls and said socket wall and the housing wall having a thickness minimized to the minimum strength required for the mechanical performance of the tool and the probe housing.

Claim 27

The apparatus as set forth in claim 23 wherein said central shell member is formed by complimentary semi-cylindrical elements to define two lengthwise extending thin separations defining lengthwise extending facing surfaces and electrical insulation separates the adjoining facing surfaces of said semi-cylindrical elements.

Claim 28

The apparatus as set forth in claim 24 wherein said annular end pieces are semi-annular and thin electrical insulation is disposed between adjoining facing surfaces of said annular end pieces.

Claim 29

The apparatus as set forth in claim 23 where there are more than one lengthwise extending thin separations in said central tubular member with thin electrical insulation separating adjoining facing surfaces at each separation.

Claim 30

The apparatus as set forth in claim 26 wherein there are more than one thin lengthwise extending separations in said annular end pieces and electrical insulation is disposed between adjoining facing surfaces at a separation.