METHODS AND APPARATUS FOR RAPIDLY MEASURING PRESSURE IN EARTH FORMATIONS

摘要

Methods and apparatus for rapidly measuring pressure in earth formations are disclosed. According to a first embodiment of the apparatus, a probe is provided with a movable piston having a sensor built into the piston. According to a second embodiment of the apparatus, the pressure sensor is mounted adjacent to or within the piston cylinder and a fluid pathway is provided from the sensor to the interior of the cylinder. Methods of operating the first and second embodiments include delivering the probe to a desired location in a borehole, setting the probe against the formation, and withdrawing the piston to draw down fluid for pressure sensing. A third embodiment of the probe is similar to the second but is provided with a spring loaded metal protector surrounding the cylinder and an annular rubber facing. The third embodiment is preferably used in a semi-continuous pressure measuring tool or an LWD tool having a piston controlled bowspring and a piston controlled articulated member carrying the probe. The tool is moved in a semi-set mode and when located at a desired depth is rapidly put in a fully-set mode.