Method and apparatus for permanent measurement of wellbore formation pressure from an in-situ cemented location
AssigneeSensor Developments AS
InventorØivind Godager
Life of this patent
Estimating the term…
Abstract
A pressure gauge system and a method for in-situ determination of a wellbore formation pressure through a layer of cement, where the pressure gauge system comprises: a housing arranged to be permanently installed in the cement on the outside of a wellbore casing, wherein said housing comprises a pressure sensor with an output pressure signal, wherein: the pressure gauge system further comprises: a first temperature sensor with a first temperature signal, a second temperature sensor with a second temperature signal; and a computer implemented compensation means arranged to receive the pressure signal, the first and second temperature signals, and calculate a temperature compensated output pressure signal.
Claims13
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.
A method for in-situ determination of a wellbore formation pressure through a layer of cement, wherein said method comprises the following steps:
- detecting an output pressure signal from a pressure sensor arranged in a housing permanently installed in said cement on the outside of a wellbore casing;
- detecting a first temperature signal from a first temperature sensor arranged to measure a first temperature outside said wellbore casing;
- calculating a temperature compensated output pressure signal in a computer, based on said pressure signal and said first temperature signal;
- isolating said pressure sensor from a first oil filled chamber with a second oil filled chamber;
- and
- allowing formation pressure to act on said first oil filled chamber through a pressure permeable filter port having a slit through a wall of said housing.
Dependencies are inferred from the claim text.