Well logging probes

Claim 2

Well-logging apparatus adapted for passage through a well bore for investigating earth formations penetrated thereby and comprising: a body; first positioning means adapted for spacing one side of said body away from one wall of a well bore and including upper and lower wall-engaging members movably mounted on said body and respectively adapted for movement between a retracted position and an extended position away from said one side of said body, and first biasing means operatively arranged for urging said wall-engaging members respectively against said one well bore wall with a combined first force of at least a predetermined magnitude; second positioning means operatively arranged on said body and including at least one wall-contacting member movably mounted on said body and adapted for movement between a retracted position and at least one extended position away from the opposite side of said body, and second biasing means operatively arranged for urging said wall-contacting member against the opposite wall of a well bore with a second force less than said predetermined magnitude; formation-investigating means adapted to be pressed against said one well bore wall movably coupled to said body and adapted for movement between a retracted position adjacent to said one side of said body and extended positions against said one well bore wall; and third biasing means operatively arranged for urging said formationinvestigating means against said one well bore wall with a third force less than said second force.

Claim 3

The well-logging apparatus of claim 1 further including actuating means on said body and operatively coupled to said members and said formation-investigating means for selectively moving said members and said formation-investigating means between their respective retracted and extended positions.

Claim 4

The well-logging apparatus of claim 1 wherein said first, second and third biasing means normally urge said membErs and said formation-investigating means toward their respective extended positions; and further including actuating means on said body and operatively coupled to said members and said formation-investigating means for selectively moving said members and said formation-investigating means from their respective extended positions to their respective retracted positions.

Claim 5

The well-logging apparatus or claim 1 wherein said formation-investigating means include a wall-engaging pad member, and at least one pivoted arm operatively coupling said pad member to said body for moving between said retracted and extended positions of said formation-investigating means.

Claim 6

The well-logging apparatus of claim 1 wherein said upper and lower wall-engaging members are respectively above and below said formation-investigating means.

Claim 7

Well-logging apparatus adapted for passage through a well bore for investigating earth formations penetrated thereby and comprising: a body; first and second positioning members movably mounted at spaced intervals along one side of said body and respectively adapted for movement between a retracted position adjacent thereto and an extended position at a selected distance therefrom for engaging one wall of a well bore; formation-investigating means on said body and including a wall-engaging member, means on said wall-engaging member adapted for measuring at least one formation characteristic upon engagement of said wall-engaging member with said one well bore wall, and support means movably coupling said wall-engaging member to said body for movement of said wall-engaging member between a retracted position adjacent to said one side of said body and extended positions in engagement with said one well bore wall; at least one third positioning member movably mounted on said body and adapted for movement between a retracted position adjacent to the opposite side of said body and extended positions in engagement with the opposite wall of a well bore; first and second biasing means for normally urging said first and second positioning members respectively to their said extended positions and against said one well bore wall with first and second forces having a combined magnitude of at least a predetermined amount; third biasing means for normally urging said third positioning member toward its said extended positions and against said opposite well bore wall with a third force less than said combined first and second forces; fourth biasing means for normally urging said wall-engaging member toward its said extended positions and against said one well bore wall with a fourth force less than said third force; and retracting means on said body and operatively coupled to said extendible members for selectively returning said extendible members to their respective retracted positions.

Claim 8

Well-logging apparatus adapted for passage through a well bore for investigating earth formations penetrated thereby and comprising: a body; first and second positioning members movably mounted at spaced intervals along one side of said body and respectively adapted for movement between a retracted position adjacent thereto and an extended position at a selected distance therefrom for engaging one wall of a well bore; formation-investigating means on said body and including a wall-engaging member, means on said wall-engaging member adapted for measuring at least one formation characteristic upon engagement of said wall-engaging member with said one well bore wall, and support means movably coupling said wall-engaging member to said body for movement of said wall-engaging member between a retracted position adjacent to said one side of said body and extended positions in engagement with said one well bore wall; at least one third positioning member movably mounted on said body and adapted for movement between a retracted position adjacent to the opposite side of said body and extended positions in engagement with the opposite wall of a well bore; first and second biasing means for normally urging said first and second positioning members respectively to their said extended positions and against said one well bore wall with first and second forces having a combined magnitude of at least a predetermined amount; third biasing means for normally urging said third positioning member toward its said extended positions and against said opposite well bore wall with a third force less than said combined first and second forces; fourth biasing means for normally urging said wall-engaging member toward its said extended positions and against said one well bore wall with a fourth force less than said third force; and retracting means on said body and operatively coupled to said extendible members for selectively returning said extendible members to their respective retracted positions.

Claim 9

The well-logging apparatus of claim 6 wherein said wall-engaging member is located between said first and second positioning members.

Claim 10

The well-logging apparatus of claim 6 wherein said support means include first and second parallel arms movable in a longitudinal plane defined by the longitudinal axes of said body and said wall-engaging member and respectively pivotally coupled to said wall-engaging member and to said body for allowing said wall-engaging member to tilt about a transverse axis perpendicular to said longitudinal plane for following irregular contours on said one well bore wall.

Claim 11

The well-logging apparatus of claim 6 wherein said first and second positioning members respectively include a laterally-movable arm member having its inner end portion pivotally coupled to said body for movement in a longitudinal plane defined by the longitudinal axes of said body and said wall-engaging member, and a roller member journalled to the outer end portion of said arm member for rotation about a transverse axis perpendicular to said longitudinal plane.

Claim 12

The well-logging apparatus of claim 9 wherein said support means include first and second parallel Arms movable in said longitudinal plane and respectively pivotally coupled to said wall-engaging member and to said body for allowing said wall-engaging member to tilt about a selected transverse axis perpendicular to said longitudinal plane.

Claim 13

Well-logging apparatus adapted for passage through a well bore for investigating earth formations penetrated thereby and comprising: a body; upper and lower wall-engaging members movably mounted on said body and respectively adapted for movement between retracted and extended positions, and first biasing means operatively arranged for urging said wall-engaging members respectively in a first direction against a well bore wall with a combined first force of at least a predetermined magnitude for spacing one side of said body away from one wall of a well bore; second positioning means operatively arranged on said body and including at least one wall-contacting member movably mounted on said body and adapted for movement between retracted and extended positions, and second biasing means operatively arranged for urging said wall-contacting member in a second direction against another wall of a well bore with a second force less than said predetermined magnitude for spacing said body away from said other well bore wall; formation-investigating means adapted to be pressed against said one well bore wall movably coupled to said body and adapted for movement between a retracted position adjacent to said body and extended positions against said one well bore wall; and third biasing means operatively arranged for urging said formation-investigating means against said one well bore wall with a third force less than said second force.

Claim 14

Well-logging apparatus adapted for passage through a well bore for investigating earth formations penetrated thereby and comprising: a body; upper and lower wall-engaging members movably mounted on said body and respectively adapted for movement between retracted and extended positions, and first biasing means operatively arranged for urging said wall-engaging members respectively in a first direction against a well bore wall with a combined first force of at least a predetermined magnitude for spacing one side of said body away from one wall of a well bore; second positioning means operatively arranged on said body and including at least one wall-contacting member movably mounted on said body and adapted for movement between retracted and extended positions, and second biasing means operatively arranged for urging said wall-contacting member in a second direction against another wall of a well bore with a second force less than said predetermined magnitude for spacing said body away from said other well bore wall; formation-investigating means adapted to be pressed against said one well bore wall movably coupled to said body and adapted for movement between a retracted position adjacent to said body and extended positions against said one well bore wall; and third biasing means operatively arranged for urging said formation-investigating means against said one well bore wall with a third force less than said second force.

Claim 15

The well-logging apparatus of claim 11 further including actuating means on said body and operatively coupled to said members and said formation-investigating means for selectively moving said members and said formation-investigating means between their respective retracted and extended positions.

Claim 16

The well-logging apparatus of claim 11 wherein said first, second and third biasing means normally urge said members and said formation-investigating means toward their respective extended positions; and further including actuating means on said body and operatively coupled to said members and said formation-investigating means for selectively moving said members and said formation-investigating means from their respective extended positions to their respective retracted positions.

Claim 17

The well-logging apparatus of claim 11 wherein said formation-investigating means include a wall-engaging pad member, and at least one pivoted arm operatively coupling said pad member to said body for moving between said retracted and extended positions of said formation-investigating means.

Claim 18

The well-logging apparatus of claim 11 wherein said upper and lower wall-engaging members are respectively above and below said formation-investigating means.