Pressure sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation

Abstract

A sensor arrangement using an optical fiber and methodologies for performing an analysis of a subterranean formation, such as a subterranean formation containing a hydrocarbon based fluid. The sensor arrangement may be used to measure one or more physical parameters, such as temperature and/or pressure, at a multiplicity of locations in the subterranean reservoir. The sensor arrangement may comprise a sensor array comprising an elongated outer casing for insertion in the subterranean formation and into a fluid in the subterranean formation. The sensor array may comprise an optical fiber defining an optical path that links one or more temperature sensors and one or more pressure sensors and transports measurement data generated by the temperature and pressure sensors. A data processing system may be connected to the sensor array to receive measurements from the sensor array and to compute one or more values of a property of an extraction installation operating on the subterranean formation.

1 . A sensor cable for measuring pressure at a plurality of spaced apart locations in a subterranean formation, the sensor cable comprising:
 (a) a first sensing portion including an elongated outer casing having a first end portion, a second opposite end portion and a side portion extending between the first end portion and the second end portion, the first sensing portion including a pressure sensor to measure pressure acting on the side portion;   (b) a second sensing portion including an elongated outer casing having a first end portion, a second opposite end portion and a side portion extending between the first and second end portions of the second sensing portion, the second sensing portion including a pressure sensor to measure pressure acting on the side portion of the second sensing portion;   (c) an interconnection portion located between the first sensing portion and the second sensing portion, the interconnection portion including a first end portion and a second opposite end portion;   (d) the first end portion of the first sensing portion being coupled to the first end portion of the interconnection portion;   (e) the first end portion of the second sensing portion being coupled to the second end portion of the interconnection portion;   (f) said first sensing portion, said second sensing portion and said interconnection portion when coupled to one another forming an elongated string-like structure;   (g) an optical fiber defining a continuous optical path extending through said first sensing portion, said interconnection portion and said second sensing portion, said optical path configured for transporting an optical signal conveying pressure information generated by the pressure sensor of said first sensing portion and the pressure sensor of said second sensing portion;   (h) said first sensing portion, said second sensing portion and said interconnection portion having a cross-sectional dimension that remains substantially constant along the string-like structure;   (i) the first sensing portion, the second sensing portion and the interconnection portion include respective first, second and third internal cavities, the sensor cable including a fluid-tight partition between the first internal cavity and the third internal cavity.