Patent ID: 9677396
Date: 2017-06-13
CPC Classifications: E21B

Claim:
1. A pressure gauge system for in-situ determination of a wellbore formation pressure through a layer of cement, said pressure gauge system comprising: a housing arranged to be permanently installed in said cement on the outside of a wellbore casing, wherein said housing comprises: a pressure sensor with an output pressure signal, wherein said pressure gauge system further comprises; a first temperature sensor with a first temperature signal arranged to measure a first temperature outside said wellbore casing; a computer arranged to receive said pressure signal and said first temperature signal, and calculate a temperature compensated output pressure signal; a first oil filled chamber; a second oil filled chamber between said first oil filled chamber and said pressure sensor, arranged to isolate said pressure sensor from said first oil filled chamber; and a pressure permeable filter port through a wall of said housing to allow formation pressure from outside said housing to act on said first oil filled chamber; wherein said filter port is a slit through said housing.