Shell Oil Comapny

Andre Franzen

Johannis Josephus Den Boer

Daniel Joinson

Kari-Mikko Jääskeläinen

Jeremiah Glen Pearce

William Birch

Arthur Alexander Van Rooyen

Paul Gerard Edmond Lumens

Johannes Maria Vianney Antonius Koelman

Alex Groen

Crispin Thomas Matthew Doyle

Christopher Barry Staveley

The spatial resolution of a fiber optical Distributed Acoustic Sensing (DAS) assembly is enhanced by:

Method and system for enhancing the spatial resolution of a fiber optical distributed acoustic sensing assembly

A distributed acoustic sensor, comprises a housing having a longitudinal bore therethrough, an optical fiber supported in the bore; and an inertial member supported within the bore, wherein the fiber is mechanically coupled to the inertial member. The inertial member may include a weight and may provides isotropic stiffness such that it deforms more readily in a first direction normal to the bore than it does in a second direction that is normal to both the bore and the first direction. The sensor may include a plurality of axially-spaced centralizers in the bore, and at least one of the inertial member and the centralizers may comprise swellable material.

Fiber optic cable with increased directional sensitivity

A system for monitoring subsidence and/or rising of a waterbottom has string of pressure sensors along the interior of a sealed -protective tube(q&#x2212;) that rests on the waterbottom and is filled with a low pressure liquid, so that any subsidence and/or rising of the can be deduced from subsidence and/or rising of a section of the tube and associated pressure variations measured by the sensors due to variation of the hydrostatic fluid pressure of the liquid in the of the tube. The tube interior is divided into segments by valves during descent to protect the sensors against hydrostatic pressure of the liquid within the tube during installation. The use of a low pressure liquid in the tube allows the use of sensitive pressure sensors which are able to monitor pressure variations of &#x2212;0.001 Bar associated with a waterbottom subsidence of &#x2212;1 cm, at a water depth of &#x3e;km where the ambient water pressure may be &#x3e;100 Bar.

Method and system for monitoring waterbottom subsidence

A pressure sensor assembly comprises a sensor housing having a flexible wall that is configured to deform in response to a pressure difference between the interior and exterior of the sensor housing; -a first fiber optical cable section that is bonded to the flexible wall of the sensor housing such that the length of the first fiber optical cable section changes in response to deformation of the wall in response to the said pressure difference; a second fiber optical cable section which is bonded to a thermal reference body, which body is connected to the sensor housing by a strain decoupled connection mechanism, such as a tack weld or flexible glue, and is configured to deform substantially solely in response to thermal deformation, such that the length of the second fiber optical cable section solely changes in response to thermal deformation of the thermal reference body.

Pressure sensor assembly and method of using the assembly

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Rijswijk, Netherlands

Andre Franzen