The invention describes a method of cement lining a wellbore to enable a fixed sensor internal of the lining to sense characteristics of the external formations surrounding the wellbore using, at the region of the sensor position, a permeability changing device before completion of setting of the cement...http://www.google.ca/patents/US6994167?utm_source=gb-gplus-sharePatent US6994167 - Method and system for cement lining a wellbore
