Wells – Above ground apparatus – With means for injecting solid or particulate material into...
Reexamination Certificate
1999-11-05
2001-09-04
Tsay, Frank (Department: 3672)
Wells
Above ground apparatus
With means for injecting solid or particulate material into...
C166S310000
Reexamination Certificate
active
06283202
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to an apparatus for dispensing a chemical additive, such as a “soap stick”, into a well to stimulate or continue fluid production from the well.
BACKGROUND
In hydrocarbon producing wells, including gas wells in particular, fluid production is sometimes impaired by migration of water and other fluids into the wellbore. In production from gas wells, for example, the migration of water into the wellbore will reduce gas production significantly in a relatively short period of time, depending upon well conditions. A known technique for recovering or stimulating well production under such circumstances involves dispensing chemical additive “sticks” or “pellets” into the wellbore from manual or automatic dispensing devices mounted on the wellhead. Additive elements, such as so-called soap sticks, may be injected into the well to form a foamy mixture of any liquids, such as water, in the well to allow gas production to recover.
Various devices have been considered in the prior art for automatically dispensing or dropping the soap sticks or pellets into gas wells to stimulate production. Such devices may be manually or remotely controlled. However, there has been a continuing need for improvements in chemical additive or so-called soap stick dispensing devices, particularly for relatively low production wells or wells which are visited relatively frequently such as once a day or once every two days, for example. Even with this frequent visitation to the well it is still necessary and desirable to provide for a soap stick dispensing device which is uncomplicated and reliable in operation and which may be remotely controlled on a predetermined time duty cycle, or otherwise, to dispense one or more chemical additive or soap sticks into the wellbore.
Still further, the complexities of certain prior art devices are such that these devices do not lend themselves to reliable operation in unattended or remotely controlled wells which require soap stick dispensing devices. An important aspect of operating remotely located gas producing wells, for example, is the reliable operation of an additive or soap stick dispensing device, the ease with which the device may be installed, serviced and additive pellets or soap sticks reloaded into the device and the cost of adding such devices to a well which requires the type of treatment provided by the device. It is to these ends that the present invention has been developed.
SUMMARY OF THE INVENTION
The present invention provides an improved apparatus for dispensing chemical additive elements, such as so-called soap sticks, into a wellbore.
In accordance with one aspect of the present invention a chemical additive or soap stick dispensing apparatus is provided which is controlled to dispense a soap stick into a wellbore at a predetermined time and is operable to provide for reloading the apparatus reliably and easily with additional additive pellets or soap sticks when the well is serviced or inspected. A further aspect of the invention is that it can be easily installed with the change of a single piping or hammer union. In this regard the soap stick dispensing apparatus is adapted to mount on the wellhead in communication with the wellbore fluid (gas) production tubing and is uniquely configured to provide for equalizing fluid pressures within the apparatus so that chemical additive pellets or soap sticks may be released reliably into the wellbore. Further in this regard, the soap stick dispensing apparatus of the invention includes a retention valve for retaining a soap stick in the apparatus under fluid pressure acting on the valve closure member. The retention valve is preferably a so-called flapper type check valve and also advantageously includes a manual actuator for moving the valve toward a closed position. The retention valve also responds to substantial balance of fluid pressure forces acting thereon to open and release a soap stick into a wellbore.
In accordance with another aspect of the invention an improved soap stick dispensing apparatus is provided which relies on wellbore fluid pressure to retain the soap stick in the dispensing apparatus and to dispense the soap stick into the wellbore. A soap stick dispensing apparatus is provided wherein a reliable flapper type check valve is used to retain the soap stick in the dispensing device until it is released by equalization of fluid pressure on both sides of the soap stick and the check valve. A second flapper type check valve is preferably provided to vent a soap stick storage chamber and to allow the first mentioned check valve to remain closed until a timer controlled motor operated valve is actuated to allow pressure gas or other wellbore fluid to equalize the fluid pressure acting across the first mentioned check valve.
Still further, the present invention provides a soap stick dispensing apparatus which includes a significant number of components which are available as standard pipe and pipe fittings thereby minimizing the requirement for special fabricated components of the device.
Those skilled in the art will further appreciate the above-mentioned advantages and superior features of the invention together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.
REFERENCES:
patent: 2981335 (1961-04-01), Bucy et al.
patent: 4694900 (1987-09-01), Behrens
patent: 4785880 (1988-11-01), Ashton
patent: 4817722 (1989-04-01), Montfort, Jr. et al.
patent: 5188178 (1993-02-01), Noyes
patent: 5709266 (1998-01-01), Kruse
patent: 5813455 (1998-09-01), Pratt et al.
Madan, Mossman, Schultz & Sriram
Schultz George R.
Tsay Frank
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