Well-based potential energy conversion systems and methods

1. A potential energy conversion system comprising:

a movable mass suspended by a line in a non-producing well having a casing, an upper section, a lower section, and a plug isolating the upper section from the lower section, the movable mass being located in the upper section within a cased interval of the non-producing well, and the line being coupled to a motor operable to lift the movable mass and a generator operable to produce electricity when lowering the movable mass;

wherein the potential energy conversion system comprises at least one of 1) a sensor located within the upper section of the non-producing well and operative to measure one or more fluid properties, gas properties, or any combination thereof within the upper section of the non-producing well, 2) one or more failsafe devices affixed to the movable mass or located upon the plug within the non-producing well, 3) a range finder effective to determine a distance between a wellhead of the non-producing well and the movable mass, the wellhead comprising a blowout preventer, or 4) any combination thereof.

2. The potential energy conversion system of claim 1 , wherein the cased interval extends between the wellhead and the plug.

3. The potential energy conversion system of claim 1 , wherein the non-producing well is substantially vertical in the upper section where the movable mass is located.

4. The potential energy conversion system of claim 1 , wherein the line extends through a sheave pulley system located at an entry to the non-producing well.

5. The potential energy conversion system of claim 1 , wherein the upper section of the non-producing well is at least partially filled with a fluid.

6. The potential energy conversion system of claim 5 , wherein the fluid is an aqueous fluid comprising a nanosodium silicate.

7. The potential energy conversion system of claim 5 , wherein the fluid is an aqueous fluid comprising one or more additives selected from the group consisting of a biocide, an anti-corrosion chemical, a scale inhibitor, a friction reducer, a rheology modifier, and any combination thereof.

8. The potential energy conversion system of claim 1 , wherein an annulus separates the movable mass from the casing, the annulus being 6 inches or less in size.

9. The potential energy conversion system of claim 1 , wherein the motor operates as the generator as the movable mass is lowered and the motor turns in reverse.

10. The potential energy conversion system of claim 1 , further comprising:

a recovery sub-system effective to retrieve the movable mass from a base of the non-producing well, if the movable mass becomes uncoupled from the line or the line fails.

11. The potential energy conversion system of claim 1 , wherein the plug is located above an interval containing a plurality of perforations in the lower section of the non-producing well.

12. The potential energy conversion system of claim 1 , further comprising:

a fluid trap for sampling fluid located at the wellhead of the non-producing well.

13. An energy conversion method comprising:

providing the potential energy conversion system of claim 1 ; and

storing potential energy by raising the movable mass, or releasing potential energy and converting the potential energy to electricity by lowering the movable mass.

14. The method of claim 13 , wherein the upper section of the non-producing well is at least partially filled with a fluid.

15. The method of claim 14 , further comprising:

measuring one or more fluid properties in the upper section of the non-producing well using the sensor and the sensor being coupled to a buoy or float effective for maintaining the sensor upon a surface of the fluid.

16. The method of claim 14 , further comprising:

collecting a sample of the fluid using a fluid trap present at the wellhead of the non-producing well.

17. The potential energy conversion system of claim 1 , further comprising a monitoring sub-system comprising the sensor,

wherein:

the sensor is located upon a buoy effective to float upon a fluid in the upper section of the non-producing well,

the sensor is a range finder and the monitoring sub-system comprises one or more reflective targets,

the sensor is a Hall effect sensor and the monitoring sub-system comprises a magnet,

the sensor is a pressure sensor,

the sensor is a flow meter,

the sensor is located upon the movable mass, or

any combination thereof.

18. A potential energy conversion system comprising:

a movable mass suspended by a line in a non-producing well having a casing, an upper section, a lower section, and a plug isolating the upper section from the lower section, the movable mass being located in the upper section within a cased interval of the non-producing well, and the line being coupled to a motor operable to lift the movable mass and a generator operable to produce electricity when lowering the movable mass;

wherein the upper section of the non-producing well is at least partially filled with a fluid, the potential energy conversion system comprises a sensor operative to measure one or more fluid properties, gas properties, or any combination thereof within the upper section of the non-producing well, and the sensor is configured to remain on a surface of the fluid.

19. The potential energy conversion system of claim 18 , wherein the sensor measures one or more quantities selected from the group consisting of fluid column height, pressure, density, redox potential, viscosity, hydrocarbon concentration, total dissolved solids, saline concentration, and any combination thereof.

20. The potential energy conversion system of claim 18 , wherein the sensor is coupled to a buoy or float effective for maintaining the sensor upon the surface of the fluid.

21. The potential energy conversion system of claim 20 , further comprising:

a range finder effective to determine a distance between a wellhead of the non-producing well and the buoy or float, the wellhead comprising a blowout preventer.

22. An energy conversion method comprising:

providing the potential energy conversion system of claim 18 ; and

storing potential energy by raising the movable mass, or releasing potential energy and converting the potential energy to electricity by lowering the movable mass.

23. The energy conversion method of claim 22 , further comprising:

measuring one or more fluid properties, gas properties, or any combination thereof within the upper section of the non-producing well.

24. A potential energy conversion system comprising:

a movable mass suspended by a line in a non-producing well having a casing, an upper section, a lower section, and a plug isolating the upper section from the lower section, the movable mass being located in the upper section within a cased interval of the non-producing well, and the line being coupled to a motor operable to lift the movable mass and a generator operable to produce electricity when lowering the movable mass;

wherein the potential energy conversion system comprises one or more failsafe devices affixed to the movable mass or located upon the plug within the non-producing well.

25. The potential energy conversion system of claim 24 , wherein the one or more failsafe devices are effective to perform one or more of increasing buoyancy, increasing drag, or increasing friction of the movable mass.

26. The potential energy conversion system of claim 25 , wherein the one or more failsafe devices comprise one or more flappers, one or more parachutes, one or more balloons, or any combination thereof.

27. The potential energy conversion system of claim 24 , wherein the one or more failsafe devices comprise at least one of a compression spring, a magnet, a collapsible structure, an inflatable structure, a parachute, a flapper, or any combination thereof.

28. An energy conversion method comprising:

providing the potential energy conversion system of claim 24 ; and

storing potential energy by raising the movable mass, or releasing potential energy and converting the potential energy to electricity by lowering the movable mass.