Wells – Processes – Cleaning or unloading well
Reexamination Certificate
1999-02-26
2001-06-26
Neuder, William (Department: 3672)
Wells
Processes
Cleaning or unloading well
C166S063000, C166S249000, C181S000500, C181S117000
Reexamination Certificate
active
06250388
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the rehabilitation, stimulation, development and maintenance of oil and water wells, pipes, reservoirs, channels and the like, and in particular to the use of air or gas apparatus for achieving same.
BACKGROUND OF THE INVENTION
Among the variety of methods known in the art of oil and water well rehabilitation and maintenance, are methods which involve the use of chemical or explosive materials for the removal of hard deposits and other encrustations. Alternative methods known in the art employ high pressure jetting techniques in the well-cleaning process. Variations of these methods are also utilized for the cleaning and maintenance of other liquid or dry storage and transport facilities such as reservoirs, crucibles, tanks, pipelines and channels.
A consideration of cleaning processes which employ explosives for the removal of hard deposits and encrustations, raises a number of important concerns. Such concerns include safety issues surrounding the manufacture, transport, usage and storage of explosive material, as well as concerns regarding the risk of structural damage to a water or oil well, or other storage or transport facility undergoing treatment.
Turning now to cleaning methods involving the use of high pressure jetting—which by way of example, are employed to remove hard scale deposits from wells and pipelines—these methods involve the application of a high pressure jet, such as a water jet, to an area of deposits, so as to first penetrate and then “strip off” the deposits by driving a fluid wedge between them and the surface to which they are attached. Disadvantages surrounding this method include limited effectiveness owing to dissipation of hydraulic power which may result from line losses, activation of the jet in a liquid environment, and difficulties in controlling movement of the jet
In addition to the above-described rehabilitation, cleaning and maintenance techniques, there are also known in the art, treatment methods which involve the use of air or gas blasting apparatus. U.S. Pat. No. 5,579,845 to Janson et al for example, entitled “Method for Improved Water Well Production”, teaches generally, a method by which pressure waveforms and mass displacement within a well bore volume are used for stimulating, refurbishing or otherwise increasing production from water wells.
Referring now to U.S. Pat. No. 4,966,326, entitled “Air-Blasting Cartridge”, there is described an example of air blasting apparatus which may be used for performing such treatment methods. This patent describes an air-blasting cartridge comprising a housing subdivided into an inlet chamber and a discharge chamber by virtue of a piston arranged lengthwise along a longitudinal axis of the housing. The inlet chamber communicates with a source of compressed air through an air admission tube which runs the length of the cartridge through an axial port of the piston. The discharge chamber communicates with the inlet chamber through an annular gap between the air admission tube and the piston, and is adapted to communicate with the surrounding atmosphere at the instant of its discharge, by means of at least one open-ended passage made in the housing close to the inlet chamber, wherein a pressure relief valve is provided at the outlet end of the passage.
While the above apparatus is intended for use in cleaning industrial pipelines including sewer pipelines, its efficiency especially with respect to well rehabilitation and maintenance—is limited by the very construction of the cartridge. In particular, the provision for the cartridge to communicate with the surrounding environment through the above-described pressure relief valve, creates a significant limitation upon the piston's opening speed which increases in accordance with the hydrostatic pressure. Further, the cartridge's pressure relief valves are likely to become clogged rather quickly, especially when the apparatus is used in a liquid environment containing an appreciable quantity of suspended particles.
SUMMARY OF THE INVENTION
The present invention seeks to provide improved apparatus, and an effective and environmentally friendly method, for water and oil well rehabilitation, stimulation, development and maintenance, which overcome the disadvantages of known art. The present invention also seeks to provide improved apparatus and method for the cleaning and maintenance of other liquid and dry storage and transport facilities.
There is thus provided, in accordance with a preferred embodiment of the invention, a self-firing and self-propelling gas impulse device which includes:
a housing having a longitudinal axis, a gas inlet port, and one or more gas discharge ports;
an inlet chamber, arranged for gas communication with a source of compressed gas via the inlet port and operative to receive compressed gas therefrom;
a pressurization chamber arranged for gas communication with the inlet chamber thereby to facilitate a buildup of pressurized gas therein, and arranged for selectable gas communication with the one or more discharge ports; and
a piston unit arranged along the longitudinal axis of the housing between the inlet chamber and the pressurization chamber, and selectably movable between a first operative position and a second operative position, whereat in the first operative position the piston unit prevents gas communication between the pressurization chamber and the one or more discharge ports, and whereat in the second operative position the piston unit is retracted so as to facilitate gas communication between the pressurization chamber and the one or more discharge ports, and the piston unit is operative to move between the first and the second operative positions in response to a force differential across the piston unit in a direction parallel to the longitudinal axis, such that when the piston unit is in the first operative position and the gas pressure in the pressurization chamber is of at least a predetermined magnitude, the piston unit is operative to move towards the second operative position in response to the gas pressure and at least a predetermined minimum force differential thereby to facilitate a rapid high pressure exhaustion of gas in the pressurization chamber to the exterior of the housing via the one or more discharge ports.
Additionally, in accordance with a preferred embodiment of the present invention, at least a portion of the piston unit is operative to move within a sealing arrangement such that when the piston unit is in the first operative position, the sealing arrangement and the piston unit cooperate so as to prevent gas communication between the pressurization chamber and the one or more discharge ports.
Further, in accordance with a preferred embodiment of the present invention, the inlet port is formed at an upstream end of the gas impulse device, and the pressurization chamber is formed at a downstream end of the gas impulse device.
Additionally, in accordance with a preferred embodiment of the present invention, the piston unit includes an upstream-facing end portion having an upstream-facing end surface and a downstream-facing end portion having a downstream-facing end surface.
Further, in accordance with a preferred embodiment of the present invention, when the piston unit is in the first operative position, the inlet chamber is operative to contain a gas having a pressure of up to a first magnitude and the pressurization chamber is operative to contain a gas having a pressure of up to a second magnitude, and when the upstream-facing end surface is exposed to the gas pressure of the first magnitude a first force is developed thereat, and when the downstream-facing end surface is exposed to the gas pressure of the second magnitude a second force is developed thereat, and the predetermined minimum force differential corresponds to the difference in the respective magnitudes between the first and second forces.
Additionally, in accordance with a preferred embodiment of the present invention, the predetermined minimum forc
Ass Yuri
Carmi Gennady
Slez Leonid
Lilling & Lilling P.C.
Neuder William
Prowell Technologies Ltd
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