Method and apparatus for MWD formation testing
First Claim
1. A formation testing tool comprising:
- a longitudinal body having a flowbore and coupled to a MWD tool;
a plurality of extendable centralizing pistons coupled to the body;
an extendable sample device coupled to the body; and
a centralizing hydraulic circuit to cause each of the plurality of centralizing pistons to extend at substantially the same rate.
1 Assignment
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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.
94 Citations
27 Claims
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1. A formation testing tool comprising:
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a longitudinal body having a flowbore and coupled to a MWD tool; a plurality of extendable centralizing pistons coupled to the body; an extendable sample device coupled to the body; and a centralizing hydraulic circuit to cause each of the plurality of centralizing pistons to extend at substantially the same rate. - 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. A method for formation testing comprising:
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communicating hydraulic fluid between a centralizing hydraulic circuit and a plurality of centering pistons; extending at substantially the same rate the plurality of centering pistons from a formation testing tool; centering the formation testing tool in a borehole; testing the formation during a drilling operation; and communicating a formation test result to a MWD tool. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification