摘要:
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.
摘要:
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.
摘要:
The invention is a system and method a system used to control multiple downhole tools with one control line. The downhole tools may comprise any hydraulically actuated tools, such as valves, packers, or perforating guns. Each tool is associated with an indexer, in one embodiment, so that the tools can be operated in concert and as a system.