Self-propelled plunger for artificial lift

1. A plunger of a plunger lift system, the plunger comprising:

a housing defining an interior cavity, the housing configured to travel between a downhole position in a wellbore and a surface of the earth and configured to displace a volume of fluid uphole of the housing responsive to downhole wellbore pressure;

a spring positioned within the interior cavity, the spring configured to transition from a charged state to a relaxed state during uphole travel of the housing to displace the volume of fluid uphole of the housing;

a propeller configured to rotate in a first direction during downhole travel of the housing and in a second direction, opposite the first direction, during uphole travel of the housing; and

a shaft positioned within the housing, the shaft comprising:

a first end coupled to the spring, and

a second end coupled to the propeller.

2. The plunger of 1 , wherein the spring is configured to charge in response to rotation of the propeller in the first direction and to relax in response to rotation of the propeller in the second direction.

3. The plunger of claim 1 , further comprising a clutch coupled to the propeller, the clutch configured to engage the shaft such that the clutch restricts a direction of rotation of the propeller in the second direction.

4. The plunger of claim 3 , wherein the clutch is configured to disengage the shaft when the housing reaches the downhole position in the wellbore, and wherein the spring is configured to change the direction of rotation of the propeller from the second direction to the first direction when the housing reaches the surface of the earth.

5. The plunger of claim 1 , wherein a longitudinal axis of the spring and a longitudinal axis of the housing are parallel to each other.

6. The plunger of claim 5 , wherein the longitudinal axis of the spring and the longitudinal axis of the housing are collinear.

7. The plunger of claim 1 , wherein the interior cavity is a first interior cavity, wherein the housing further defines a second interior cavity adjacent to the first interior cavity, and wherein the propeller is disposed in the second interior cavity.

8. The plunger of claim 7 , wherein the first interior cavity and the second interior cavity are separated by a partition.

9. The plunger of claim 7 , further comprising at least one slot formed in a portion of the housing circumscribing the second interior cavity.

10. An artificial lift method comprising:

lowering a plunger from a surface of the earth to a downhole position in a wellbore, the plunger comprising:

a housing configured to travel between the downhole position and the surface;

a cavity formed in the housing;

a spring positioned within the cavity;

a propeller configured to rotate in a first direction during lowering of the plunger and in a second direction, opposite the first direction, during uphole travel of the plunger; and

a shaft positioned within the housing, wherein a first end of the shaft is coupled to the spring and a second end of the shaft is coupled to the propeller;

storing energy within the spring while lowering the plunger from the surface to the downhole position; and

releasing energy stored within the spring when the plunger travels uphole to displace a volume of fluid uphole of the plunger in response to downhole wellbore pressure.

11. The artificial lift method of claim 10 , further comprising:

rotating the propeller in a first direction during lowering of the plunger to store energy within the spring; and

rotating the propeller in a second direction, opposite the first direction, during uphole travel of the plunger to release the stored energy within the spring.

12. The artificial lift method of claim 10 , further comprising changing a direction of rotation of the propeller between the first direction and the second direction using a clutch coupled to the propeller.

13. The artificial lift method of claim 10 , wherein the direction of rotation of the propeller is changed from the first direction to the second direction when the plunger reaches the downhole position in the wellbore and from the second direction to the first direction when the plunger reaches the surface.

14. The artificial lift method of claim 10 , wherein the spring is a helical spring, wherein storing energy within the spring comprises charging the helical spring, and wherein releasing the stored energy within the spring comprises relaxing the charged helical spring.

15. An artificial lift method comprising:

moving a plunger located at a downhole position in a wellbore in an uphole direction responsive to wellbore pressure to displace a volume of fluid uphole of the plunger; and

releasing energy stored within a spring disposed in the plunger while displacing the volume of fluid in the uphole direction, the released energy assisting to displace the volume of fluid in the uphole direction, wherein releasing energy stored within the spring disposed in the plunger while displacing the volume of fluid in the uphole direction comprises rotating a propeller of the plunger using the released energy to assist in displacing the volume of fluid in the uphole direction.

16. The artificial lift method of claim 15 , wherein rotating a propeller of the plunger using the released energy to assist in displacing the volume of fluid in the uphole direction comprises relaxing the spring to rotate the propeller of the plunger.

17. The artificial lift method of claim 15 , further comprising storing energy within the spring while the plunger descends in a downhole direction.