Hughes Aircraft Company

Abb Vetco Gray Incorporated

Dtc International, Inc.

J Douglas Smith

William C Parks

Elvin E Herman

Bart E Likes

Douglas A Norton

A subsea control module consists of three primary sections. The lower portion consists of a plate for carrying hydraulic couplings and hydraulic passages from valves to couplings. The lower portion contains a sub-assembly containing electro-optical couplings with direct sealed passages and wiring to a dry electronics chamber. The valve manifold has multiple pressure supply sources and a plurality of valves mounted therein. An outside portion of the valves are exposed so that the valves are externally accessible without disassembly of the subsea control module assembly, which facilitates an increase in accessibility and a reduction in maintenance times and costs. Electronics, wiring and solenoid valves are located in a one atmosphere, dry nitrogen purged chamber in a pressure vessel dome. The dry chamber has direct access to transducers and solenoid valves, thereby eliminating subsea cables. A mandrel extends below the device for engagement with a central locking mechanism in a receiver baseplate. Since the mandrel is located below the SCM rather than extending therethrough, space within the device is not occupied by the mandrel. Therefore each module is of a reduced size, which permits the retrieval and immediate replacement of the module by an ROV, which reduces the need to make several trips between the surface and subsea.

Subsea control module

Improved fiber optics pressure sensor transducers utilizing fiber optics in an interferometer sensing element. Included is a bellows-type pressure-to-movement converter that translates sensed pressure into linear displacement. That displacement is mechanically coupled to, and thereby varies the length of one leg of a fiber optics interferometer as a function of pressure. A temperature compensator is attached to the sensing or reference optical fiber of the interferometer. The temperature compensator causes corrective changes in the length of that optical fiber to which it is attached, thereby compensating for opposing temperature effects on other parts of the interferometer. Threaded studs attached to flexible stress reducers which are in turn coupled to optical fiber grippers provide means for adjusting interferometer optical fiber pre-tension and rotation to optimize polarization. In combination, the threaded studs with their attached flexible stress reducers, coupled via fiber grippers to the interferometer optical fibers, serve to minimize fiber bending and localized stress points which otherwise might weaken the tensioned fibers of the interferometer. A bourdon tube embodiment of the pressure-to-movement converter having a curved tang and attached flexible link converts rotational motion of the bourdon tube movement end to linear displacement.

Fiber optics pressure sensor transducer having a temperature compensator

An optical interferometer is provided for measuring downhole pressures by detecting a distance across a gap of an optical transmission pathway. The optical interferometer includes a pressure responsive member which, in response to downhole wellbore pressures, alters the distance between a light reflector and a lens. A partially reflective coating is deposited upon the pressure responsive member, which provides the light reflector, and the lens. The optical interferometer further includes a plurality of support members for the lens, with at least one of the plurality of support members having a different coefficient of thermal expansion from another support member so that when heated to downhole temperatures, thermal expansion of the support members will result in mutually offsetting displacements so that thermal expansion of the support members will not affect the gap over a range of downhole wellbore temperatures.

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Houston, TX, United States of America

J Douglas Smith