Schlumberger Technology Corporation

Elizabeth B Dussan, V

Jagdish H Shah

Michael G Supp

Nathan Church

Brindesh Dhruva

Aaron Jacobson

Fredrick A Jenet

Bradley Kerr

Jennifer Trittschuh

Stephane Pierre

A formation testing probe assembly comprising an elongated packer having a surface configured to be urged by the probe assembly towards a wall of a wellbore extending through the formation. The formation testing probe assembly further comprises a plate embedded in the elongated packer and including a central structural portion extending along a centerline of a substantial length of the plate, wherein the central structural portion is substantially thicker than remaining portions of the plate.

Elongated probe

A method for determining formation fluid pressure in earth formation surrounding a borehole wall uses a downhole probe coupled to a variable-volume cavity. The probe is driven into contact with formation at the borehole wall. The method includes expanding the volume of the cavity during a first period of time to establish fluid communication between tool fluid and formation fluid, by withdrawing a minimal amount of fluid from the formation. During a second period of time the tool pressure is allowed to equilibrate to formation pressure. When pressure equilibrium is established, formation fluid pressure is set equal to tool pressure. A preferred embodiment includes terminating expanding the volume of the cavity on detecting a break in the mud cake seal. An associated formation pressure tester tool includes an elongated body; a probe defining a formation fluid inflow aperture, an electromechanical assembly defining a variable-volume cavity, a pretest flow line coupling the aperture to the cavity, a pressure sensor coupled to the cavity; and downhole electronic means for controlling the expansion of the volume of the cavity.

Determining the pressure of formation fluid in earth formations surrounding a borehole

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Ridgefield, CT, United States of America

Elizabeth B Dussan, V