Patent ID: 6994167
Filing Date: 2006-02-07
Classification: C04B,C09K,E21B

Abstract:
1. A method of providing a permanent fluid communication through cement lining of a well bore between an external formation and a fixed sensor internal of the lining to sense characteristics of the external formations surrounding the wellbore, comprising the step of creating at the region of the sensor position a permanent fluid communication through the cement lining between the external formation and the sensor by modifying the permeability of the cement lining by activating a permeability changing device installed on wellbore casing adjacent to the sensor and increasing the permeability locally in the region of the sensor position, in which a cement curing retarder is introduced into the cement slurry in the region of the sensor to prevent curing of the cement in the region thereby providing the fluid communication between the formation and the sensor.