Method and apparatus for MWD formation testing
First Claim
1. A formation testing tool comprising:
- a longitudinal body having a flowbore;
a plurality of extendable centralizing pistons coupled to the body;
an extendable sample device coupled to the body; and
a centralizing hydraulic circuit configured to cause each of the plurality of centralizing pistons to extend at substantially the same rate.
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Accused Products
Abstract
A method and apparatus for formation testing is disclosed. In a preferred embodiment, a formation testing tool includes a longitudinal body with a flowbore; a plurality of extendable centralizing pistons coupled to the body; an extendable sample device coupled to the body; and a centralizing hydraulic circuit configured to cause each of the plurality of centralizing pistons to extend at substantially the same rate. The centralizing hydraulic circuit includes a series of flow control and pressure-determining valves configured to extend the centralizing pistons at substantially the same rate, and to help maintain stability in the hydraulic circuit in response to external pressures. In some embodiments, the extendable sample device is preferably configured to be recessed beneath a surface of the body in a first position and to extend beyond the surface in a second position. The extendable sample device is preferably extended to contact the borehole wall substantially normal to the wall, protecting the sample device from excessive bending moments and other excessive forces.
138 Citations
29 Claims
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1. A formation testing tool comprising:
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a longitudinal body having a flowbore;
a plurality of extendable centralizing pistons coupled to the body;
an extendable sample device coupled to the body; and
a centralizing hydraulic circuit configured to cause each of the plurality of centralizing pistons to extend at substantially the same rate. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A formation testing tool comprising:
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a longitudinal body having a surface;
an extendable sample device coupled to the body, the extendable sample device configured to be recessed beneath the surface of the body in a first position and to extend beyond the surface in a second position.
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8. A formation testing tool comprising:
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a longitudinal body;
an extendable sample device coupled to the body; and
a plurality of extendable centralizing pistons coupled to the body, the extendable centralizing pistons being configured to extend at substantially the same rate. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for formation testing comprising:
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extending at substantially the same rate a plurality of centering pistons from a formation testing tool;
centering the formation testing tool in a borehole; and
testing the formation. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification