Patent Application
20160102533
Producing oil and gas wells sometimes produce water as well as hydrocarbons from formation. If the height of the produced water column in the wellbore is sufficient, it will exert pressure on the formation which can exceed the formation's pressure, and thus inhibit further production. To overcome this, the water is sometimes removed from the well by a plunger lift system. A plunger deployed in the well's bore drops to near bottom hole into the water column, where it forms a piston between the formation's production pressure below and the water above. Gas produced below the plunger forces it and the water above it toward the surface, where the water can be removed and the pressure on the formation from the water column can be reduced. This function is performed cyclically, typically without intervention by the operator.
The plunger may develop quite a bit of velocity in its upward travel, so in most plunger lift systems, a ‘catcher’ is deployed in the lubricator at the top of the well's casing above surface. These lubricator/catchers are used to seal the top of the well's bore from atmosphere so that produced hydrocarbons and water can be collected from the casing below the catcher, and can provide both access to the wellbore, and a means for capturing the plunger at the upper end of its stroke where it can be removed for inspection, repair or replacement.
The lubricator/catcher may be provided with a spring or shock absorber system as well as a plunger-capture system, to protect the wellbore's sealed top from damage from by a hard hit from the plunger. Hard hits by a plunger can cause damage to the well's casing, surface equipment and/or the plunger itself. Since the well is unattended in operation, generally, such damage may not be obvious or immediately apparent.
In this invention, a component is added to a typical lubricator which includes a coil spring above a striker block, a piston above the striker block, the piston sealed but moveable within the bore of the lubricator, above the piston another spring or set of spring washers, a space, and above the space a thin membrane or wall in a top nut or seal at the top of the lubricator. If the plunger reaches the lubricator's top end with sufficient force, it will compress the coil spring and move the striker block to push the piston upward within the bore of the lubricator, the piston will compress the second spring or set of spring washers, and the top end of the piston, which is preferably pointed, will pierce the membrane or wall in the top of the lubricator. The lubricator will remained sealed because the piston is sealed within the bore of the subassembly within the lubricator, but the top nut or seal will be pierced, providing an obvious, externally observable, indication of the fact that at least one “heavy hit” has been made by the plunger to the lubricator and top-hole equipment. The spring compression forces can be designed so that the indication provided is indicative of forces which have exceeded a predetermined level of force. In this way, preventive or repair maintenance can be done by the operator prior to the plunger system failing due to absorption of too many heavy hits, or too much force from the plunger. The types of failure that heavy hits from plungers can cause include (but are not limited to) stretching of threaded components which weakens their strength and effectiveness as seals, or degradation of sealing elements.
A parts list with numerical indicators is also shown, which numerals are indicated on each of the figures.
This invention provides a catastrophic or heavy-hit indicator subassembly for a lubricator in a plunger-lift system for oil and gas production wells.
The lubricator shown in
In an embodiment, the subassembly comprises a striker block 5 at the bottom end of a compression spring 8 which may be a coil spring, the compression spring 8 surrounding a hit indicator spring housing 1. The housing 1 is surrounded by the upper end of the coil spring 8, and the housing 1 includes in its inner part a cylinder 1a. The cylinder is open at its top and its bottom ends. The cylinder 1 has a bottom opening which is large enough to permit the lower end of a piston 3 to pass through the opening, which may be sealed by positioning an elastic o-ring 6 between the piston's lower end extention 3a and the housing 1 cylinder's bottom opening.
Midway along the piston 3 is a feature which provides a stop 3b, above which the piston's upper end 3c continues as a smaller-diameter cylinder, on which a number of Belleville washer springs 4 are stacked. Above the washers 4, and surrounding the upper tip of the piston, which may be pointed, a cap 2 is provided, attached with a seal 7 to the housing 1 at its upper end (the housing 1). The cap 2 is visible to an observer from outside of the lubricator through a port in the upper portion of the lubricator assembly (#).
When a plunger of they lift system is forced with sufficient energy to strike the lubricator and the heavy hit subassembly, the following will occur.
The plunger strikes the striker block 5, pushing it upward within the lubricator, compressing coil spring 8 and moving a sufficient distance and with sufficient force, the striker block 5 will in turn strike the lower end of the piston 3a and force it upwards within the cylinder 1a to compress the Belleville spring discs 4, and if sufficient force is supplied by the plunger to the subassembly, the Belleville spring discs 4 will compress sufficiently that the pointed end of the piston 3c will pierce the indicator cap 3.
When the indicator cap 3 is pierced, it will be deformed such that an observer from outside of the lubricator can see that there has been a heavy hit, and can determine that the lubricator and top-hole equipment may require servicing or inspection.
The springs may be chosen to have characteristics such as a particular designed force to compress, to tailor the subassembly to indicate hits of specific characteristics (such as minimum force required to deform the cap).
In the preceding description, for purposes of explanation, numerous details are set out in order to provide a thorough understanding of the embodiments of the invention and how it is meant to work. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the invention as claimed. The above descriptions are intended to be examples only. Alterations, modifications, and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined by the claims of the patent flowing from the specification.
| Number | Date | Country | |
|---|---|---|---|
| 62062487 | Oct 2014 | US |
