Wells – Processes – Separating material entering well
Reexamination Certificate
2000-09-22
2001-12-18
Suchfield, George (Department: 3672)
Wells
Processes
Separating material entering well
C166S105100, C166S106000, C166S311000, C166S370000, C210S170050, C210S747300, C417S088000, C417S313000
Reexamination Certificate
active
06330915
ABSTRACT:
FIELD OF THE INVENTION
Protection of downwell pumps from damage by sand which is entrained in fluids to be pumped, for example oil or water from oil wells and water wells in sandy formations.
BACKGROUND OF THE INVENTION
Downwell pumps are placed in a well near its bottom, for providing pressure to move well fluid to the surface. Examples are oil wells and water wells, where the pump draws well fluids from the surrounding formation. Commonly such formations include sand which abrasively wears the pump structure when it passes through the pump. This requires much more frequent pump service than if the pump were pumping a similar fluid without sand in it.
Removal and replacement of a downwell pump is costly both in labor and in production lost due to down time of the well.
The usefulness of screens to protect the pump is more theoretical than actual because of the tendency of screens to clog. Centrifugal separators have proved to be far superior for downhole work, and are exemplified for this purpose by Laval Jr. U.S. Pat. Nos. 3,289,608 and 4,072,481, which are incorporated herein by reference in their entirety for their showing of useful structures and utility.
While these show a suitably effective separation of sand ahead of the inlet of the pump, they leave unsolved the optimum disposition of the separated sand. In one embodiment the sand is simply returned to the well, where it can contribute to plugging the formation.
In another, the sand is flushed from a T into a fluid stream that joins the output fluid from the pump on its way to the surface. The problem faced by this arrangement is the possibility that the sand outlet may become plugged or overloaded. In that event, the system will have to be raised to the surface and cleaned out. This is an expensive situation which is intended to be avoided by this invention.
BRIEF DESCRIPTION OF THE INVENTION
A system according to this invention includes a centrifugal separator of the type which has an internal cylindrical wall along which a rapid flow of fluid circulates in a helical pattern from an inlet port that directs the rapidly flowing stream tangentially along the cylindrical wall. This flow continues until it encounters a spin plate.
The spin plate reverses the axial direction of stream flow which then flows centrally in the opposite direction to and out of an outlet port. Sand that is moved toward the wall by the centrifugal force flows through a gap near the spin plate, and into a lower sand collection chamber, accompanied by some liquid to form a sand-enriched flow. The pump draws the sand-free flow from the outlet port of the separator. This results in an incoming flow of sand-laden fluid into the inlet port of the separator.
According to a feature of this invention, an ejector having a flow passage with a reduced injector section and an ejection port into it, receives a pumped flow of sand free liquid from the pump through a conduit that receives liquid from the pump outlet and returns it to the effluent stream. The ejection port is connected to the outlet from the sand collection chamber. A backflush nozzle is spaced from and faces the injection port to direct a liquid stream into it in the event it is clogged.
According to a preferred but optional feature of the invention, a check valve communicating with the outlet port of the sand collection chamber diverts sand from the ejector port in the event the injection port or the outlet becomes clogged.
There results a sand separator system which is resistant to clogging, while protecting the pump from sand.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:
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Fletcher Yoder & Van Someren
Suchfield George
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