Array antenna for measurement-while-drilling
First Claim
Patent Images
1. An array antenna formed on a body of a MWD/LWD tool disposed in a well, said array antenna comprising:
- a plurality of cross-dipole elements formed on the tool body, each of said plurality of cross-dipole elements comprising at least first and second wires crossing the surface of a high magnetic permeability material, wherein none of the wires is in electrical contact with each other or the high magnetic permeability material;
whereineach of said plurality of cross-dipole elements is disposed within a slot recess in an outer surface of a wall of said tool body and;
whereinthe first wire traverses at least two elements to form an antenna with a magnetic dipole moment in a first direction, and the second wire traverses the same elements in a different direction to form a magnetic dipole in a second direction.
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Abstract
An electromagnetic antenna for Measurement-While-Drilling (MWD) applications is disclosed. The antenna can include several array elements that can act alone or together in various measurement modes. The antenna elements can be disposed in tool body recesses to be protected from damage. The antenna elements can include a ferrite plate crossed or looped by independent current carrying conductors in two or more directions forming a bi-directional or crossed magnetic dipole. Although disclosed as a MWD system conveyed by a drill string, basic concepts of the system are applicable to other types of borehole conveyance.
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Citations
70 Claims
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1. An array antenna formed on a body of a MWD/LWD tool disposed in a well, said array antenna comprising:
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a plurality of cross-dipole elements formed on the tool body, each of said plurality of cross-dipole elements comprising at least first and second wires crossing the surface of a high magnetic permeability material, wherein none of the wires is in electrical contact with each other or the high magnetic permeability material;
whereineach of said plurality of cross-dipole elements is disposed within a slot recess in an outer surface of a wall of said tool body and;
whereinthe first wire traverses at least two elements to form an antenna with a magnetic dipole moment in a first direction, and the second wire traverses the same elements in a different direction to form a magnetic dipole in a second direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An array antenna formed on a tool body conveyed along a well borehole, said array antenna comprising:
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a plurality of cross-dipole elements formed on the tool body, each of said plurality of cross-dipole elements having cross magnetic dipoles;
whereineach of said plurality of cross-dipole elements is disposed within a recess in an outer surface of a wall of said tool body wherein said recess does not penetrate through said wall of said tubular. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for producing or sensing an antenna response of an array antenna, the method comprising:
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forming said array antenna on a LWD/MWD tool body, said array antenna comprising a plurality of cross-dipole elements each disposed in a slot recess on an outer surface of the tool body, each of said plurality of cross-dipole elements comprising at least first and second wires crossing the surface of a high magnetic permeability material, wherein none of the wires is in electrical contact with each other or the high magnetic permeability material; and combining responses of said elements to obtain said antenna response; wherein the first wire traverses at least two elements to form an antenna with a magnetic dipole moment in a first direction, and the second wire traverses the same elements in a different direction to form a magnetic dipole in a second direction. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A method for producing or sensing an antenna response of an array antenna, the method comprising:
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forming said array antenna on a tool body conveyed along a well borehole, said array antenna comprising a plurality of cross-dipole elements formed on the tool body, each of said plurality of cross-dipole elements being disposed in a recess in an outer surface of said tool body wherein said recess does not penetrate through said wall of said tool body and each cross-dipole element comprising at least two wires crossing the surface of a high magnetic permeability material, wherein none of the wires is in electrical contact with each other or the high magnetic permeability material; and combining responses of said elements to obtain said antenna response. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70)
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Specification