Retrievable hydraulic subsea bop control pod

Abstract

Systems and methods for improved hydraulic control systems for actuation of subsea equipment in deep water are disclosed. The hydraulic control system relies on smaller fluid flow associated with a hydraulic pressure pulse to actuate the small volume actuation control valve. In one embodiment, the system includes small diameter control umbilical hoses and pilot-operated valves with low actuation volumes. Particularly, a hydraulic control system for reducing the signal time to a subsea blowout preventer in water depth up to and greater than about 5000 feet. Some embodiments comprise a valve arrangement which hydraulically actuate one side of a hydraulic control function, while simultaneously evacuating the opposing circuit both at the seabed and at the surface. Some embodiments comprise an umbilical hose located proximate the center of an umbilical bundle. Preferably, the umbilical hose has a plurality of layers of reinforcing fibers which increase with the diameter of the reinforcement layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]None.STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]None.REFERENCE TO A MICROFICHE APPENDIX[0003]None.BACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The present invention relates to hydraulic control systems for actuation of subsea equipment, particularly to a hydraulic control system and method for use in deep water with a subsea Blowout Preventer (BOP) stack, more particularly for a hydraulic control system and method utilizing a retrievable control pod for the actuation of subsea Blowout Preventer (BOP) stacks.[0006]2. Description of the Related Art[0007]Offshore drilling for oil and natural gas from floating vessels is conventionally done through a drilling riser between the floating drilling vessel and a BOP stack located at the seabed.[0008]The hydraulic functions of the BOP stack may be controlled by a hydraulic control system or an electro-hydraulic control system.[0009]The first shallow-wat...

AI Technical Summary

Benefits of technology

"The present invention is about a hydraulic control system for a subsea BOP stack. It includes a retrievable hydraulic control pod with hydraulic receptacles and an umbilical attached to the drilling riser. The hydraulic control system has a subsea hydraulic umbilical line, a lower marine riser package with a hydraulic receptacle, a hydraulic control pod with a hydraulic connector for mating with the receptacle, and at least one lower marine riser package and pod umbilical hydraulic connector for mating with each other. The system allows hydraulic fluid to flow from the subsea line through the riser package and into the control pod. The invention also includes a hydraulic control pod with a male frustoconical hydraulic connector that can be retrieved while the umbilical control hose remains attached to the drilling riser. The invention also provides a method for converting an existing hydraulic control system to allow for the retrieval of the control pod while keeping the umbilical hose attached to the riser."

Problems solved by technology

They also discovered that the currents in deep water could cause severe and deleterious “vortex-induced vibration” (“VIV”) in the control pod deployment cable 201 and the control pod umbilical 202 clamped to it, often severely damaging the expensive umbilical.

However, with the control pod umbilical attached to the riser, a control pod may be retrieved for inspection and repair only by tripping the entire LMRP with both pods attached, which is extremely expensive and time consuming.

However, this and other prior art systems all require that the existing control pods with frustoconical hydraulic receptacles be replaced, at very high cost.

Still further, the junction plate 202A is a complicated, heavy, and expensive machined part in which multiple hydraulic seals reside; although these seals are usually robust, the junction plate arrangement has the potential for multiple leak-paths between the umbilical and the control pod.

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