Gas separation: processes – Degasification of liquid – Plural successive degassing treatments
Reexamination Certificate
1999-02-16
2001-03-06
Smith, Duane S. (Department: 1724)
Gas separation: processes
Degasification of liquid
Plural successive degassing treatments
C095S253000, C095S259000, C095S260000, C096S182000, C096S217000, C166S267000, C166S357000, C210S188000
Reexamination Certificate
active
06197095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a system and method for subsea separation of well fluids and solids and, more particularly, to a compact separating system that may be deployed and operated at deep and ultra-deep water depths for processing well fluids and solids prior to transport to the surface, or disposal either subsea or to the surface.
2. Description of the Background
In recent years, the oil and gas industry has found significant oil and gas reserves in deepwater offshore locations. Many discoveries have been made in over three thousand feet of water with a number of high potential discoveries being located in over five thousand feet of water. In the not too distant future, discoveries in depths of over ten thousand feet are inevitable. As the production depths increase, the cost of transporting well fluids from the seabed to the surface also increases. Transporting well fluids that contain significant amounts of undesirable solids and water from significant depths limits the flow of the desirable hydrocarbon products to the surface due to significant cost limitations of the internal diameter of the riser pipe from the sea bottom. Not only are there significant inefficiencies associated with transporting multi-phase fluid flow from the seabed but also there are other high costs including production problems such as erosion, corrosion, and hydrate formation. At the present time, technical and economical limitations effectively prevent profitable deepwater production. As the depths reach new levels, there is no current technology that can be used to commercially exploit deep water reserves. On the other hand, the medium to longer term strategic business plans of some oil and gas producers are dependent on the finding of appropriate technology to exploit deep water reserves.
The methods currently available to produce and separate the constituent hydrocarbon products from associated solids and produced water utilize production separation equipment that is located topside on fixed or floating facilities. It would be highly desirable if there were means to reduce the cost of these facilities and avoid the other aforementioned costs with a commercially feasible method of separating by-products of oil and gas production at the seabed. Unfortunately, the methods and systems for separating multiphase fluids presently used are not feasible in the remote, hostile, and problematic environment at the seabed in deep waters. Nonetheless, such a highly desirable means would preferably separate some unprofitable by-products, namely water and solids, on the seabed and dispose of them into the reservoir and/or onto the seabed.
Numerous speculative subsea separation solutions have been put forward where either one or two such separation processes occur. However, these processes are based on the use of conventional equipment that operates in a manner consistent with topside operations. These solutions fail to address all the issues associated with subsea separation because the adoption of conventional technology is impractical to use as a seabed system. For instance, in one proposed subsea separation method put forward, it is submitted the reliability is highly suspect due to unsolved problems that might be encountered such as erosion, corrosion, hydrate formation, and that furthermore the efficiency of the system is too low such that it would have flow through rates that are unprofitably low. In another proposed subsea system, the size of the system to be placed underwater is so large as to make the system economically unfeasible for use at significant depths. Topside systems cannot simply be lowered onto the seabed because of numerous problems that are encountered thereby.
It is submitted that the above discussed proposals for subsea operation do not provide a compact subsea production system that is commercially feasible for producing from significant depths. Consequently, there remains a need for an improved and compact deepwater production separation system that is capable of efficiently separating the constituents of hydrocarbons production, namely oil, gas, water, and solids. It would be desirable to have a system designed to operable in virtually any water depth and having significantly reduced size with respect to production efficiency as compared to existing technology. Thus, such a system would lend itself to be of particular value to production in much greater depths, such as water depths over ten thousand feet deep or more. Those skilled in the art have long sought and will appreciate the present invention which provides solutions to these and other problems.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an improved subsea separation system and method.
Another object of the present invention is to provide a subsea system that is suitable for remote operation in that the components efficiently operate with a wide range of multiphase fluids.
Yet another object of the present invention is to provide a system that utilizes inherently reliable cyclonic action to provide the system reliability required for remote operation.
Yet another object of the present invention is a system design that results in the reduction of mobilization and demobilisation costs.
A presently preferred feature of the invention is a process that separates at an initial stage by-products that otherwise may cause damage to downstream production elements such as pipework, valves, and vessels through corrosion, erosion, and hydrate formation.
Another presently preferred feature of the invention is a process that separates bulk gas after removal of solids to enhance solids removal, promote operation of subsequent liquid-liquid hydrocyclone operation, and reduce the size required for the gravity separator.
A presently preferred advantage of the present invention is that a much smaller gravity separator can be used than would be practical for typical surface separation operation.
Another advantage of the present invention is a presently preferred modular construction of the system components for use in a single housing or frame for reliable transport to the ocean floor.
These and other objects, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims. However, it will be understood that the above discussed presently preferred and/or available objects, features, and advantages of the method and system of the present invention are not all inclusive, represent only a few of the objects, features, and advantages, and are not intended to limit the invention or claims to the invention in any way but are merely intended as an aid to those of skill in the art having interest in practicing the invention for those purposes.
Thus, a subsea method for separation of multiphase production fluids from one or more wells drilled below a body of water is disclosed that comprises steps such as positioning separation equipment below a surface of the body of water and in proximity with the one or more wells. The one or more wells are connected to the separation equipment to introduce the multiphase production fluids to the separation equipment. The separation equipment is operated in a definite sequence. In one embodiment of the invention where solids are or may be present in the fluid, the solids are first separated from the multiphase production fluids to produce the solids and a first stage processed fluid. If gas is present in the first stage processed fluid, the bulk gas and liquids are then separated from the first stage processed fluid to produce a gas output and a second stage processed fluid. When water is or may be present, the second stage fluid is preseparated to produce a third stage processed fluid. Oil and water and any residual gas are separated from the third stage processed fluid in the fourth stage to produce an oil output and a fourth stage processed fluid. Finally, cleaning of the fourth stage processed fluid yields a water o
Ditria John C.
Hadfield David A.
Nash Kenneth L.
Smith Duane S.
LandOfFree
Subsea multiphase fluid separating system and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Subsea multiphase fluid separating system and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Subsea multiphase fluid separating system and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445249