Tool and method for measuring properties of an earth formation surrounding a borehole

摘要

A measuring tool for measuring for example the pore pressure, from a cased hole is disclosed. A holder (7, 18, 23) is attached to the outside of the casing (4), in which a sensor (8) capable of measuring a physical property is mounted and contacting means (9, 16, 18, 19, 21, 22) which are capable of bringing the sensor into permanent direct contact, fluid contact or gas contact with the earth formation (2), irrespective of the local diameter of the borehole (1). The contacting means may comprise explosives (9), associated protective means (12, 15), projecting hard porous material (16), a flexible plastic container filled with grease or bow spring.