Liquid buildup can occur in aging production wells and can reduce the well's productivity. To handle the buildup, operators can use beam lift pumps or other remedial techniques, such as venting or “blowing down” the well. Unfortunately, these techniques can cause gas losses. Moreover, blowing down the well can produce undesirable methane emissions. In contrast to these techniques, operators can use a plunger lift system, which reduces gas losses and improves well productivity.
A plunger lift system 10 of the prior art is shown in
The two-piece plunger 50A of
When used in the system 10 of
When the sleeve 60 reaches the ball 70, they unite into a single component. With the plunger 50A deployed to handle liquid buildup, operators set the well in operation. Gas from the formation enters through casing perforations 18 and travels up the production tubing 16 to the surface, where it is produced through lines 32/34 at the lubricator 30. Liquids may accumulate in the well and can create back pressure that can slow gas production through the lines 32/34. Using sensors and the like, a controller 36 operates a valve 38 at the lubricator 30 to regulate the buildup of pressure in the tubing 16. Sensing the slowing gas production due to liquid accumulation, the controller 36 shuts-in the well to increase pressure in the well.
As high-pressure gas accumulates, the well reaches a sufficient volume of gas and pressure. Eventually, the gas pressure buildup pushes against the combined sleeve 60 and ball 70 and lifts them together to the lubricator 30 at the surface. The column of liquid accumulated above the plunger 50A likewise moves up the tubing 16 to the surface so that the liquid load can be removed from the well.
In this way, the plunger 50 essentially acts as a piston between liquid and gas in the tubing 16. Gas entering the production string 16 from the formation through the casing perforations 18 acts against the bottom of the plunger 50A (mated sleeve and ball 60/70) and tends to push the plunger 50A uphole. At the same time, any liquid above the plunger 50A will be forced uphole to the surface by the plunger 50A.
As the plunger 50A rises, for example, the controller 36 allows gas and accumulated liquids above the plunger 50A to flow through lines 32/34. Eventually, the plunger 50A reaches a catcher 40 on the lubricator 30 and a spring (not shown) absorbs the upward movement. The catcher 40 captures the plunger's sleeve 60 when it arrives, and the gas that lifted the plunger 50 flows through the lower line 32 to the sales line. A decoupler (not shown) inside the lubricator 30 separates the ball 70 from the sleeve 60. The ball 70 can then immediately fall toward the bottom of the well. The catcher 40 holds the sleeve 60 and then releases the sleeve 60 after the ball 70 is already on its way down the tubing 16.
Dropped in this manner, the sleeve 60 and ball 70 fall independently inside the production tubing 16. The sleeve 60 with its central passage 62 can have gas flow through it as the sleeve 60 falls in the well. On the other hand, flow travels around the outside of the ball 70 as the ball 70 falls in the well. Unfortunately, the ball 70 tends to fall slower than the sleeve 60. Therefore, the system 10 must properly time the dropping of the ball 70 and sleeve 60 so that the ball 70 has sufficient time to fall downhole before the sleeve 60 is allowed to fall. Solutions for decoupling the ball 70 and for timing the dropping of the ball 70 and the sleeve 60 are disclosed in U.S. Pat. Nos. 6,719,060; 6,467,541; and 7,383,878, for example. Although such schemes may be effective, what is needed is a more robust approach with less complexity.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
A plunger lift system has a plunger with a main sleeve and an ancillary sleeve that dispose in tubing downhole. The sleeves move uphole in the tubing from a dowhole bumper to an uphole lubricator when downhole pressure acts against the mated sleeves. Both sleeves have a passage therethrough for fluid communication, and the sleeves can fall independently of one another from the surface to the downhole bumper. Preferably, the ancillary sleeve falls at a faster rate downhole than the main sleeve. When downhole, however, the sleeves mate together and prevent passage of fluid through the sleeves. As gas pressure builds downhole, the gas ultimately lifts the mated sleeves and pushes a column of liquid above the sleeves to the surface.
The main sleeve disposes in the tubing uphole of the ancillary sleeve. The main sleeve has a narrow stem on its distal end with openings that communicate with the sleeve's internal passage. A nodule also extends from the distal end.
As noted previously, the ancillary sleeve disposes in the tubing downhole from the main sleeve. The uphole end of the ancillary sleeve fits at least partially on the narrow stem of the main sleeve. When mated, the ancillary sleeve closes off fluid communication through the main sleeve's passage. Likewise, the nodule on the main sleeve engages in the ancillary sleeve's orifice so the fluid communication through the ancillary sleeve's passage is also closed off.
The plunger lift system also has a downhole bumper that provides a cushioned landing for the sleeves. At the surface, the plunger lift system has a lubricator with a valve and a catcher. A controller at the lubricator can control the passage of fluid flow by operating the valve based on conditions in the tubing. This can allow the controller to build pressure in the tubing for a plunger lift cycle. When the mated sleeves reach the surface by application of fluid pressure from downhole, the catcher can engage the main sleeve. The catcher can be manual or can be operated automatically by the controller. The ancillary sleeve in contrast to the main sleeve is free to fall downhole in advance of the main sleeve. Once both sleeves have been dropped, the two sleeves mate downhole at the bumper again so the plunger lift cycle can repeat itself.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.
A gas well in
As shown, the well has production tubing 16 disposed in casing 14, which extend from a wellhead (not shown). Formation fluids enter the casing 14 via casing perforations 18. The produced fluids then enter the production tubing 16 and bypass a bottomhole bumper 20 positioned downhole. At the wellhead, a lubricator 30 routes produced fluids to a sales line.
A multi-sleeve plunger 100 disposes in the tubing 16 and can move between the bumper 20 and the lubricator 30 to lift accumulated liquid to the surface. As shown briefly in
Initially, the plunger 100 rests on the bottomhole bumper 20 toward the base of the well. When disposed at the bumper 20, the two sleeves 110/150 mate together. As gas is produced through lines 32/34 on the lubricator 30, liquids may accumulate in the wellbore and create back-pressure that can slow gas production. Using sensors and the like, a controller 36 operates a valve 38 at the lubricator 30 to regulate the buildup of gas in the tubing 16. Sensing the slowing gas production, the controller 36 shuts-in the well to increase pressure in the well as high-pressure gas begins to accumulate.
When sufficient gas volume and pressure level are reached, the gas pushes against the plunger 100 and eventually pushes the plunger 100 upward from the bumper 20 toward the lubricator 30 as illustrated in
As the plunger 100 rises, the controller 36 allows gas and accumulated liquids above the plunger 100 to flow through the outlets 32/34. Eventually, the plunger 100 reaches the lubricator 30, and a spring 42 absorbs the plunger's impact. A catcher 44 in the assembly 40 can then capture the plunger's main sleeve 110 if desired. Meanwhile, the gas that lifted the plunger 100 flows through the lower outlet 32 to the sales line. Once the gas flow stabilizes, the controller 36 can shut-in the well and releases the main sleeve 110, which drops back downhole to the bumper 20. Ultimately, the cycle can repeat itself.
The catcher 44 can hold the main sleeve 110 and can control the release of the main sleeve 110 to fall downhole after the ancillary sleeve 150. Yet, in some circumstances, using the catcher 44 to hold the main sleeve 110 may not be required during a lift cycle. Instead, the main sleeve 110 can be held in the lubricator 30 by the immediate uphole flow of gas during the lift cycle. This may occur for a sufficient amount of time after the ancillary sleeve 150 has descended into the well.
For its part, the ancillary sleeve 150 is free to drop off the main sleeve 110 when pressure fails to support it thereon. Thus, the ancillary sleeve 150 can promptly fall off the main sleeve 110 and toward the bottom of the well. Accordingly, a particular decoupler is not needed for this implementation to decouple the ancillary sleeve 150.
In general, the catcher 44 can have a conventional design when used. As shown in
Alternatively, the catcher 44 can be automated. In such an auto catch assembly, the catcher 44 can automatically catch the plunger's main sleeve 110 when it arrives at the surface during a lift cycle. A sensor can be used to detect the plunger's arrival if necessary.
The controller 36 can then indicate when the main sleeve 110 is to trip downhole rather than allowing the sleeve 110 to drop when the flow rate momentarily decreases. For such an automated catcher 44, a spring and piston arrangement 48 can bias the ball 46 using compressed gas from a source controlled by the controller 36. The pressure can be applied to the spring and piston arrangement 48 using diaphragm topworks (not shown) or other device. With pressure applied, the ball 46 forces into the lubricator's pathway so the ball 46 can engage the plunge's main sleeve 110. The controller 36 can release gas pressure from the spring and piston arrangement 48. At this point, the weight of the main sleeve 110 can push the ball 46 out of the way so the sleeve 110 is free to fall into the well.
As shown in
Because the ancillary sleeve 150 may fall promptly, it may fall while the well is still flowing. Because it is a sleeve with an internal passage and smooth external surface, the ancillary sleeve 150 can avoid issues encountered by dropped balls or the like and may be able to avoid friction issues and other problems when falling against flow. Nevertheless, the ancillary sleeve 150 is preferably designed to fall faster than the main sleeve 110. Therefore, timing the dropping of the two sleeves 110/150 may not be as much of an issue in the plunger lift system's operation than found in other systems.
When the separate sleeves 110/150 reach the bottom of the well, they nest together in preparation for moving upwardly once pressure builds up. For example, the ancillary sleeve 150 falls into any liquid near the bottom and lands on the bumper 20. The main sleeve 110 drops after the ancillary sleeve 150 to the bumper 20. When the main sleeve 110 reaches the ancillary sleeve 150, they unite into a single component. Any gas entering the tubing 16 from the formation then starts to act against the bottom of the mated sleeves 110/150 and tends to push them together uphole. In this way, any new liquid above the mated sleeves 110/150 can be forced uphole to the surface.
Turning to
Turning to the main sleeve 110, the exterior of the main sleeve 110 can have ribbing 120 or other features for creating a pressure differential across the sleeve 110 when disposed in tubing. The ribbing 120 may be of any suitable type, including wire windings or a series of grooves or indentations. The ribbing 120 creates a turbulent zone between the sleeve 110 and the inside of the producing tubing, which restricts liquid flow on the outside of the sleeve 110. The ribbing 120 can also be used as a catch area for holding the sleeve 110 at the wellhead, as described previously.
The sleeve's internal passage 112 can define a fish neck or other profile 116 allowing for retrieval of the sleeve 110 if needed. At its distal end, the main sleeve 110 defines a narrow stem 114 on which the ancillary sleeve 150 can fit when mated thereto. The distal end of this narrow stem 114 has a nodule 115 and defines ports 118 communicating with the sleeve's internal passage 112. These ports 118 allow flow through the main sleeve's internal passage 112 as it falls in the well.
Turning to the ancillary sleeve 150, its internal passage 152 can also have a fish neck profile 156 for retrieval. The uphole end of the ancillary sleeve 150 is open to fit onto the main sleeve's narrow stem 114. The lower end of the ancillary sleeve 150, however, is closed except for an orifice 155 through which the nodule 115 of the main sleeve 110 can fit when mated thereto.
As shown in
The same is true for the ancillary sleeve 150 so that both the open proximal end and the distal orifice 155 preferably align with the passage's centerline C. As will be appreciated, the surface areas of the sleeves 110/150 against which flow acts, the weight of the sleeves 110/150, their diameters, the number of openings 118, and other variables can be designed for a particular implementation and can depend on several factors, such as size of tubing, expected gas flow, formation fluid properties, etc.
As shown in
As noted above, the main sleeve's exterior can have ribbing 120 or other features for creating a pressure differential across the sleeve 110 when disposed in tubing. For example, the main sleeve 110 as shown in
As shown in
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. Although the multi-sleeve plunger disclosed herein includes at least two sleeves with internal passages, for example, it will be appreciated with the benefit of the present disclosure that the disclose plunger can have more than two sleeves that move independently of one another in the tubing and that close off fluid communication therethrough when mated together. In other words, the disclosed plunger can have two or more sleeves similar to the main sleeve 110 of
Moreover, the sleeves of the disclosed multi-sleeve plunger have been depicted without seals. Use of seal may be unnecessary for at least partially closing off fluid communication between the sleeves when mated together so the mated sleeves can be pushed uphole by pressure. However, it will be appreciated that seals may be used on the sleeves, but the seals are preferably used on abutting surfaces so as not to interfere with the free decoupling between the sleeves.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.