Wells – With eduction pump or plunger – Having sediment trap or deflector
Reexamination Certificate
2000-12-13
2003-03-18
Bagnell, David (Department: 3672)
Wells
With eduction pump or plunger
Having sediment trap or deflector
C166S157000, C166S205000, C166S227000
Reexamination Certificate
active
06533033
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to pumping of natural resources from below ground to the surface and more specifically to devices to protect and improve the efficiency of pumps used for such purposes.
2. Background Information
In the United States and throughout the world, a variety of natural resources including oil, water, and methane (a natural gas), are found beneath the earth's surface and brought to the surface through a variety of wells. In some instances these resources are under pressure and will naturally flow through the well to the surface without application of other means. In other cases, a pump which has much of its components on the surface is used to pump the resource from the ground. In some instances, a pump, often a submersible pump, is placed beneath the surface in a production zone within or near the source of the resource.
In most cases in which an underground pump is used, a hole is drilled from the surface to the production zone and a pipe of some type is inserted into the hole between the surface and the production zone. The well is often “cased” by forcing concrete into the area between the outer surface of the pipe and the surface of the hole. The area near the production zone (the area within or near the source of the resource) is usually below the pipe and casing or placed in communication with the inside of the pipe or pipe and casing by the inclusion of holes in the pipe and/or casing. If an underground pump is used, the pump is suspended beneath the surface in the production zone.
The extraction of methane from coal deposits in many western states provides a good example of a well which uses an underground pump. The methane gas is entrained in water which permeates porous and permeable layers of coal found beneath the surface. A hole is drilled from the surface to the top of the coal deposit. The hole is cased with pipe from the surface to the top of the coal deposit. The production zone is a hole within the coal and is open to the cased area. A delivery pipe runs within the cased pipe from the surface to the production area and a submersible pump is affixed to the underground end of the delivery pipe. Ordinarily, water and methane will seep from the coal into the hole around the pump. The water and a small amount of methane are pumped through the delivery pipe to the surface where the water and methane are separated. Most of the methane flows up the cased hole outside the delivery pipe and is then removed and processed. The removal of water and methane from the production zone causes a pressure differential between the area close to the pump and outlying areas which tends to cause the water and methane to flow from the coal to the production zone near the pump.
A number of conventional submersible pumps may be used for this purpose and nearly all of them have a screened intake port through which the water enters the pump body. The water drawn into the pump also includes fine coal particles and other solid matter. Usually, after a period of operation, the solid particles (including coal particles) clog the pump's intake port and, more importantly, the pump impellers within the pump. Such clogging causes a variety of problems. The most obvious problem arising from clogging is that the extraction of water stops and methane production falls off dramatically or ceases, because there is no longer a pressure differential between the production zone and the surrounding area of the coal deposit. In addition, if the pump continues to operate with little or no flow of water, the pump will overheat and eventually fail. In many cases where the pump's intake port or pump impellers are clogged, the pump must be retrieved from the hole and cleaned. In cases where the pump fails or is damaged, the pump must be retrieved and either replaced or repaired. Often a system of sensors and controls are employed which sense that the intake port is clogged and the pump is laboring and the pump is automatically shut off.
Another significant problem which arises with the use of submersible pumps is overheating.
Another problem in coal bed methane production is associated with wells which are particularly “gassy.” That is, significant amounts of methane are pumped up through the delivery pipe with the water and do not flow up the well outside of the delivery pipe. In most cases this results in significant amounts of methane being lost.
Another problem associated with submersible pumps, especially higher horsepower pumps, is pump failure caused by what is known as “upthrust.” Most submersible pumps are manufactured as a series of stages stacked within a cylindrical case. Each stage includes an impeller and all of the impellers are usually powered by a single electric motor. When the pump is started up, the first stage impels the liquid up into the second stage and then the first and second stages impel the liquid up into the third stage. This process continues until all the stages are engaged and the liquid is forced out of the pump. As each stage is engaged, it adds its pumping force to the force provided by the previous stages. At startup, this combination of the upward force imparted by the lower stages of the pump or upthrust causes considerable wear and fatigue upon the elements of the upper stages of the pump. In some cases, a pump will even fail immediately upon startup because the upthrust of the lower stages of the pump cause failure of one or more of the upper stages.
The invention presented in the present application is believed to solve, in a simple and effective fashion, problems which have long plagued persons engaged in pumping resources from a well with a submersible pump: a pump protection system which provides a screen between the production zone and the pump intake port to prevent unwanted solids from reaching and clogging the pump intake port, which provides a method of cleaning such solids from the screen without removing the pump protection system or the pump from the production zone, which acts to eliminate or greatly reduce entrained gases from moving with the pumped fluid through the delivery pipe, which acts to prevent overheating, and which prevents pump failure due to upthrust at startup.
Although the pump protection system of the instant invention may be used in a variety of situations for extraction of a variety of resources, the following example is based upon the extraction of methane and water from underground coal seams, such methane is often described as “coal bed methane.” The well is as described above. The pump protection system of the instant invention is attached to the delivery pipe near the bottom of the delivery pipe and completely surrounds the pump. The water from the production zone must pass through a protection system screen before it enters the intake port of the pump. If the protection system screen becomes clogged, a self-cleaning method is provided such that the system may be back-flushed and particles removed from the protection system screen with no reverse flow through the pump. The pump protection system of the instant inventions solves problems related to overheating by preventing clogging in a manner which also provides for a flow of cooling fluid around of the pump motor. The configuration of the pump protection system and the flow path of water within the pump protection system also helps to prevent methane from flowing with the water through the delivery pipe. The pump protection system of the instant invention also includes a pressure relief valve which acts to prevent upthrust damage at pump startup.
The ideal pump protection system should screen unwanted solid particles from reaching the intake port of the pump and clogging the intake port or jamming or causing excessive wear of the internal pump impellers. The ideal pump protection system should also provide a self-cleaning method whereby solid particles which collect upon the protection system screen may be flushed from the protection system screen without retrieving the pump or pum
Bagnell David
Walker Zakiya
Woodle Gene R.
LandOfFree
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