Passive flowmeter for determining the flow rate and the direction of flow in a well

Claim 2

A flowmeter for use in a well comprising: a support; a spinner rotatably mounted about an axis on said support; magnetic detector means fixed to said support and including a magnetic core between two magnetic terminal portions having spaced end surfaces of different areas substantially located in a plane extending perpendicularly to said axis, said magnetic detector means further including an electrically conductive coil wound about said core; and magnetic generator means fixed to said spinner and including at least one north pole and at least one south pole facing said plane opposite the end surfaces of said terminal portions, to generate a variable magnetic flux through said coil when said spinner is rotated, said poles being angularly spaced about said axis by an angle such that the variations in the generated magnetic flux present a cycle ratio other than unity.

Claim 3

A flowmeter according to claim 1, wherein each terminal portion has a number of end surfaces regularly disposed around said axis, the end surfaces of one of said terminal portions being alternately disposed with the end surfaces of the other terminal portion.

Claim 4

A flowmeter according to claim 1, wherein said magnetic core has a longitudinal axis disposed parallel to said axis.

Claim 5

A flowmeter according to claim 1, wherein said magnetic core has a longitudinal axis disposed transversely relative to said axis.

Claim 6

A flowmeter according to claim 1, wherein a non-magnetic material is disposed between the terminal portions of said magnetic detector means, the surface of said non-magnetic material being substantially level with the end surfaces of said terminal portions.

Claim 7

A flowmeter according to claim 1, wherein said magnetic generator means comprises a number of north poles and an equal number of south poles, the north and south poles being distributed alternately about said axis.

Claim 8

A flowmeter according to claim 2, wherein the number of end surfaces of each terminal portion is equal to three.

Claim 9

A flowmeter according to claim 7, wherein the magnetic generator means has a north pole and a south pole which are angularly spaced by 150°.

Claim 10

A flowmeter according to claim 1, wherein each terminal portion of said magnetic detector means has a single end surface, and wherein said magnetic generator means has a north pole and a south pole which are angularly spaced by an angle of 90°.

Claim 11

A flowmeter according to claim 1, wherein said support comprises first and second cavities separated by a non-magnetic wall, said first cavity being sealed from the well fluids and adapted to receive said magnetic detector means and said second cavity being subjected to the pressure of the well fluids and adapted to receive said magnetic generator means.

Claim 12

A flowmeter sensor for determining the speed and the direction of rotation of a spinner rotatably mounted about an axis on a support, comprising: a magnetic element fixed to said support and including a core portion between first and second terminal portions, said terminal portions having each a plurality of end surfaces which are substantially located in a plane perpendicular to said axis, the end surfaces of said first and second terminal portions having different areas and being alternately disposed around said axis, a detecting coil wound around said core portion; and at least one magnetic north pole and one magnetic south pole fixed to said spinner opposite the end surfaces of said terminal portions, to generate a variable magnetic flux through said coil when said spinner is rotated, said poles being angularly spaced about said axis by an angle such that the variations in the generated magnetic flux present a cycle ratio other than unity.

Claim 13

A flowmeter sensor for determining the speed and the direction of rotation of a spinner rotatably mounted about an axis on a support, comprising: a magnetic element fixed to said support and including a core portion between first and second terminal portions, said terminal portions having each a plurality of end surfaces which are substantially located in a plane perpendicular to said axis, the end surfaces of said first and second terminal portions having different areas and being alternately disposed around said axis, a detecting coil wound around said core portion; and at least one magnetic north pole and one magnetic south pole fixed to said spinner opposite the end surfaces of said terminal portions, to generate a variable magnetic flux through said coil when said spinner is rotated, said poles being angularly spaced about said axis by an angle such that the variations in the generated magnetic flux present a cycle ratio other than unity.

Claim 14

A flowmeter for use in a well comprising: a support; a spinner rotatably mounted about an axis on said support; magnetic detector means fixed to said support and including a magnetic core between, and perpendicular to, first and second magnetic terminal portions, each of said terminal portions having a plurality of equal-area end surfaces regularly disposed around said axis, the end surfaces of said first terminal portion being alternately disposed with the end surfaces of said second terminal portion, wherein the surface area of the end surfaces of said first terminal portion is different than the surface area of the end surfaces of said second terminal portion and wherein said first end surfaces are placed in different planes relative to each other and to the end surfaces of said second terminal, said magnetic detector means further including an electrically conductive coil wound about said core; and magnetic generator means fixed to said spinner and including at least one north pole and at least one south pole facing a plane parallel to the end surfaces of said first and second terminal portions, to generate a variable magnetic flux through said coil when said spinner is rotated, said poles being angularly spaced about said axis by an angle such that the variations in the generated magnetic flux present a cycle ratio other than unity.

Claim 15

A flowmeter for use in a well comprising: a support; a spinner rotatably mounted about an axis on said support; magnetic detector means fixed to said support and including a magnetic core between, and perpendicular to, first and second magnetic terminal portions, each of said terminal portions having a plurality of equal-area end surfaces regularly disposed around said axis, the end surfaces of said first terminal portion being alternately disposed with the end surfaces of said second terminal portion, wherein the surface area of the end surfaces of said first terminal portion is different than the surface area of the end surfaces of said second terminal portion and wherein said first end surfaces are placed in different planes relative to each other and to the end surfaces of said second terminal, said magnetic detector means further including an electrically conductive coil wound about said core; and magnetic generator means fixed to said spinner and including at least one north pole and at least one south pole facing a plane parallel to the end surfaces of said first and second terminal portions, to generate a variable magnetic flux through said coil when said spinner is rotated, said poles being angularly spaced about said axis by an angle such that the variations in the generated magnetic flux present a cycle ratio other than unity.