Automatic chemical treatment system with integral flush fluid dispenser

1. A wellbore chemical treating system, comprising:

a pressure vessel for containing a treating chemical, the pressure vessel closed to atmospheric pressure;

a first controllably operated valve in direct fluid communication between an outlet of the pressure vessel and a well for selectively controlling the flow of the chemical from the pressure vessel directly to the well;

a pressurized gas located in the pressure vessel wherein the pressure exerted by the pressurized gas causes the chemical to flow from the pressure vessel to the well through the first valve;

a fluid supply tank in communication with the well and configured to retain a same pressure as exists in the well;

a second controllably operated valve disposed between the well and an outlet of the fluid supply tank for selectively controlling flow of fluid in the tank to the well; and

a controller for selectively operating the first valve and the second valve.

2. The system of claim 1 wherein the controller is adapted to cause the second valve to operate for a time sufficient to discharge substantially all the fluid in the tank.

3. The system of claim 1 wherein an inlet to the fluid tank is operably coupled to an outlet of the well so as to be refilled by fluid produced from the Earth's subsurface.

4. The system of claim 1 wherein at least one of the pressure vessel and the fluid tank includes a float operable to close an outlet of at least one of the pressure vessel and the fluid tank when a respective level of one of the chemical and the fluid therein falls below a selected level.

5. The system of claim 1 wherein the controller is configured to operate the first valve-and the second-valve substantially simultaneously.

6. The system of claim 1 wherein the controller is configured to operate the first valve and the second valve at different times from each other.

7. The system of claim 1 wherein the first-valve comprises a solenoid to effect operation thereof.

8. The system of claim 1 wherein the second valve comprises a motor/gear set to effect operation thereof.

9. A method for injecting treatment chemical in liquid form into a well, comprising:

applying compressed gas to the chemical to pressurize the chemical;

at selected times making an hydraulic connection directly between the pressurized chemical and an interior of the well, thereby enabling the pressurized chemical to flow into the well;

storing fluid produced from the well, the storing performed at a pressure extant on the well; and

at selected times making an hydraulic connection between the stored, produced fluid and the well so that the produced fluid flows into the well by gravity.

10. The method of claim 9 further comprising reducing a pressure of the pressurized liquid to a selected amount above a pressure extant in the well.

11. The method of claim 9 wherein the selected times of making the hydraulic connection between the chemical and the well have a duration and frequency selected to inject a predetermined quantity of the chemical into the well.

12. The method of claim 9 further comprising determining an amount of the stored fluid and stopping the making the hydraulic connection between the stored fluid and the well when the amount of stored fluid falls below a selected threshold and if the hydraulic connection between the chemical and the well is being made at the same time, stopping the making thereof.

13. A method for injecting treatment chemical in liquid form into a well, comprising:

at selected times automatically causing the chemical to flow directly into the well;

storing fluid produced from the well at a pressure extant on the well; and

at selected times automatically making an hydraulic connection between the stored, produced fluid and the well so that the produced fluid flows into the well by gravity.

14. The method of claim 13 further comprising reducing a pressure of the pressurized liquid to a selected amount above a pressure extant in the well.

15. The method of claim 13 wherein the selected times of injecting the chemical and making hydraulic connection to the well have a duration and frequency selected to inject a predetermined quantity of the chemical into the well.

16. The method of claim 13 further comprising determining an amount of the stored fluid and stopping the injecting the chemical and making the hydraulic connection when the amount of stored fluid falls below a selected threshold.

17. A method for injecting treatment chemical in liquid form into a well, comprising:

at selected times automatically causing the chemical to flow directly into the well; and

at selected times automatically making an hydraulic connection between produced fluid from the well held at a pressure extant on the well, and to the well, so that the produced fluid flows into the well by gravity.

18. The method of claim 17 further comprising reducing a pressure of the pressurized liquid to a selected amount above a pressure extant in the well.

19. The method of claim 17 wherein the selected times of injecting the chemical and making hydraulic connection to the well have a duration and frequency selected to inject a predetermined quantity of the chemical into the well.