Wells – Above ground apparatus – With flow restrictions
Reexamination Certificate
1999-11-30
2002-04-09
Bagnell, David (Department: 3672)
Wells
Above ground apparatus
With flow restrictions
C137S375000
Reexamination Certificate
active
06367546
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally piping components for high pressure oil wells, and in particular to the use of ceramic material in wear components for a pressure reducer assembly for such wells.
BACKGROUND OF THE INVENTION
Many oil well facilities around the world operate under high pressure. In other words, the pressure within the well is sufficiently high (e.g., 3000 to 5000 psi) to carry the crude oil to the surface without pumping. Unless restricted, the crude oil flows to the surface at a high velocity and contains sand and other debris which erodes the interior surfaces of the oil well piping components. In order to limit the amount of sand and debris that is carried with the extracted oil, the high well pressure is maintained in the exit piping by using a pressure reducer at the head end of the well. For instance, a six inch inner diameter well pipe is reduced to three inches through a series of narrow channel pipe components. The flow channel is then further reduced to less than one inch, or even less than one-half inch, in the pressure reducer assembly.
The known pressure reducing devices are made of carbon steel and have tungsten carbide inserts to line the inside surfaces of the flow channels. The abrasive oil-and-sand mixture not only wears away the inside wall of the flow channels, but also backwashes around the outside diameter of the flow reducer and wears away the steel body of the flow reducer, resulting in gross failure of the reducer itself. Often, the metal housing surrounding the flow reducer is severely worn as well. Continuous erosion of the pressure reducer over time results in a slow and continuous loss of desired operating pressure until gross failure requires replacement. This loss in operating pressure causes an ever-increasing sand content, resulting in less efficient oil production. The average life of the known flow reducers is about 4 to 12 weeks. Oil well downtime to replace a pressure reducer and/or other components, is usually four to eight hours. High pressure oil wells typically produce about 5,000 to 12,000 barrels of oil a day. It is readily apparent that the present construction of the oil well pressure reducing assemblies leaves something to be desired with respect to wear resistance and useful life.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of this invention to extend the operating life of high pressure oil well components, resulting in more efficient oil production.
Another object of this invention is to minimize abrasive wear of the steel surfaces of high pressure oil well components.
Another object of this invention is to minimize erosive channeling (backflow) between a pressure reducer and the reducing valve body by sealing any voids between the reducing valve and the pressure reducer.
Another object of this invention is to increase the wear resistance of flow channel surfaces that are susceptible to erosion wear.
A still further object of this invention is to minimize turbulent flow to lessen the likelihood of channeling and erosion.
The above and other objects are achieved in a pressure reducer made entirely of solid ceramic material, in a ceramic-lined reducing valve, and in ceramic-lined narrow bore piping components, with all ceramic elements susceptible to flow containing modified flow channel designs. The ceramic material may be any one selected from the class of technical ceramics, referring to ceramic materials exhibiting superior mechanical properties.
The ceramic pressure reducer lessens both the interior and exterior erosion that occurs with a steel pressure reducer. The ceramic pressure reducer is fitted into the downstream end of a ceramic-lined reducing valve. The replaceable ceramic linings of the reducing valve are more wear resistant than steel, thus protecting the interior steel surfaces of the reducing valve flow channels. The ceramic liners also provide better sealing of the area between the pressure reducer and the reducing valve channel wall. The ceramic liners in the narrow bore components, and in the reducing valve, not only wear better than steel or carbide materials, but also allow for a more precise flow channel design, thus lessening the deteriorating affects of turbulent vortex flow.
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Baenziger Carl R.
Mentesh Ibrahim M.
Carpenter Advanced Ceramics Inc.
Dann Dorfman Herrell and Skillman, P.C.
Dougherty Jennifer R.
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