The present disclosure relates to a plunger lift apparatus for lifting of formation liquids in a hydrocarbon well. More specifically the disclosure is directed to a two-piece plunger that separates at a well surface allowing each piece to descend into a well separately and unite at a well bottom, upon which the united plunger raises to the surface.
A plunger lift is an apparatus that can be used to increase the productivity of oil and gas wells. In the early stages of a well's life, liquid loading may not be a problem. When production rates are high, well liquids are typically carried out of the well tubing by high velocity gas. As a well declines and production decreases, a critical velocity is reached wherein heavier liquids may not make it to the surface and start falling back to the bottom of the well exerting pressure on the formation, thus loading up the well. As a result, the gas being produced by the formation can no longer carry the liquid being produced to the surface. As gas flow rate and pressures decline in a well, lifting efficiency can decline substantially.
Well loading typically occurs for two reasons. First, as liquid comes in contact with the wall of the production string of tubing, friction slows the velocity of the liquid. Some of the liquid may adhere to the tubing wall, creating a film of liquid on the tubing wall which does not reach the surface. Second, as the liquid velocity continues to slow, the gas phase may no longer be able to support liquid in either a slug form or a droplet form. Along with the liquid film on the sides of the tubing, a slug or droplet(s) may begin to fall back to the bottom of the well. In an advanced situation there will be liquid accumulated in the bottom of the well. The produced gas must bubble through the liquid at the bottom of the well and then flow to the surface. However, as gas advances through the accumulated liquid, the gas may proceed at a low velocity. Thus, little liquid, if any, may be carried to the surface by the gas, resulting in only a small amount of gas being produced at the surface.
A plunger lift system can act to remove accumulated liquid in a well. That is, a plunger lift may unload a gas well and, in some instances, unload the gas well without interrupting production. A plunger lift system utilizes gas present within the well as a system driver. A plunger lift system works by cycling a plunger into and out of the well. During a cycle, a plunger typically descends to the bottom of a well passing through fluids within the well. Once the liquids are above the plunger, these liquids may be picked up or lifted by the plunger and brought to the surface, thus removing most or all liquids in the production tubing. The gas below the plunger will push both the plunger and the liquid on top of the plunger to the surface completing the plunger cycle. As liquid is removed from the tubing bore, an otherwise impeded volume of gas can begin to flow from a producing well. The plunger can also keep the tubing free of paraffin, salt or scale build-up.
In certain wells, fluid buildup hampers the decent of the plunger to the well bottom. Thus, wells with a high fluid level (e.g., high gas flow rates and/or high liquid accumulations) tend to lessen well production by increasing the cycle time of the plunger lift system, specifically by increasing the plunger descent time to the well bottom. Prior art designs have utilized two-piece plungers having a ball and sleeve arrangement to reduce decent time to the well bottom. Typically, the ball portion of the plunger is received in a lower end of a hollow sleeve portion of the plunger wherein the ball and sleeve unite at the well bottom. Once united, the ball is disposed in a lower opening of the sleeve and prevents fluid passage there through. At this time, gas beneath the united two-piece plunger accumulates and raises the plunger through the well. Further, the gas pressure beneath the united plunger maintains the ball within the lower opening of the sleeve. At the surface, the united two-piece plunger is received in a lubricator where an extracting rod passes through the sleeve and dislodges the ball. The ball is then free to fall to the bottom of the well. The sleeve is typically held in the lubricator for a time by flow from the well or by mechanical engagement. Once released, the sleeve falls to the well bottom where it unites with the ball.
While ball and sleeve plunger improve the cycle time in high flow wells, these ball and sleeve plungers provide little benefit once flow of the well decreases. That is, such ball and sleeve plungers are primarily utilized for the first few months of a well's production. After this time, multiple alternate plungers (e.g., by-pass, one-piece) may be utilized with the reduced flow rates. However, changing from a ball and sleeve plunger to another plunger type typically requires reconfiguring the lubricator to remove the extraction rod that is necessary for use with a ball and sleeve plunger.
Provided herein, is a two-piece plunger that may be utilized with a standard lubricator free of an extraction rod. The two-piece plunger provides the benefit of reducing cycle time in high flow wells while allowing a user to replace the two-piece plunger at a later time without having to reconfigure the lubricator.
According to one aspect, a two-piece plunger is provided having an upper sleeve or upper member and a lower lance or lower member that engages (e.g., unites) and disengages the upper member. The upper and lower member are sized for receipt within production tubing of a well and are configured to move upwardly in the production tubing when united and to fall separately when disengaged (e.g., separated). The upper sleeve is generally cylindrical and has an open top end, an open bottom end and an internal or central bore extending there between. The internal bore provides a fluid path through the upper sleeve when the upper sleeve is not engaged by the lower member. The lower lance member includes a dislodging rod that is sized to extend through internal bore of the upper sleeve when the two pieces are united. More specifically, a tip or upper end of the rod extends beyond a top end of the sleeve when the members are united. The lower member also includes a body connected to a lower end of the rod. The body has one or more internal and/or external flow paths that allow fluid to flow across the body when the body is disposed within the production tubing and when the lower member is disengaged from the upper member. When united, fluid flow (e.g., gas flow) is substantially prevented across the united plunger. That is, the lower lance member plugs the upper sleeve when these members are united to substantially prevent gas flow across the united plunger. This allows gas below the united plunger to move the plunger upward in a well. In addition, formation fluid above the plunger are lifted to the surface. When these members are separated at the surface, fluid is able to flow across and/or through each member allowing these members to descend into the production tubing of the well against fluid flow.
The size and weight of the two members may be varied to provide desired properties to the plunger. For instance, the internal diameter of the central bore of the upper sleeve maybe sized to provide a desired descent rate. Accordingly, the diameter of the rod of the lower member may be correspondingly sized. Further, the bore may be sized to maintain the upper sleeve within a lubricator using fluid flow through the lubricator (i.e., free of mechanical capture). In this regard, the internal bore may include a reduced diameter section. However this is not a requirement. In a further arrangement, a mechanical catcher may engage the sleeve when the sleeve is in the lubricator.
Further, the materials forming the upper and lower pieces may be varied and the two pieces may use common or different materials. For instance, the lower member may be formed of titanium while the upper member is formed of steel (e.g., stainless steel).
Reference will now be made to the accompanying drawings, which at least assist in illustrating the various pertinent features of the presented inventions. The following description is presented for purposes of illustration and description and is not intended to limit the inventions to the forms disclosed herein. Consequently, variations and modifications commensurate with the following teachings, and skill and knowledge of the relevant art, are within the scope of the presented inventions. The embodiments described herein are further intended to explain the best modes known of practicing the inventions and to enable others skilled in the art to utilize the inventions in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the presented inventions.
A typical installation plunger lift system 50 can be seen in
In some embodiments, the lubricator assembly 10 contains a plunger auto catching device 5 and/or a plunger sensing device 6. The sensing device 6 sends a signal to surface controller 15 upon plunger 100 arrival at the top of the well and/or dispatch of the plunger 100 into the well. When utilized, the output of the sensing device 6 may be used as a programming input to achieve the desired well production, flow times and wellhead operating pressures. A master valve 7 allows for opening and closing the well. Typically, the master valve 7 has a full bore opening equal to the production tubing 9 size to allow passage of the plunger 100 there through. The bottom of the well is typically equipped with a seating nipple/tubing stop 12. A spring standing valve/bottom hole bumper assembly 11 may also be located near the tubing bottom. The bumper spring is located above the standing valve and can be manufactured as an integral part of the standing valve or as a separate component of the plunger system.
Surface control equipment usually consists of motor valve(s) 14, sensors 6, pressure recorders 16, etc., and an electronic controller 15 which opens and closes the well at the surface. Well flow ‘F’ proceeds downstream when surface controller 15 opens well head flow valves. Controllers operate based on time, or pressure, to open or close the surface valves based on operator-determined requirements for production. Alternatively, controllers may fully automate the production process.
When motor valve 14 opens the well to the sales line (not shown) or to atmosphere, the volume of gas stored in the casing and the formation during the shut-in time typically pushes both the fluid load and the plunger 100 up to the surface. Forces which exert a downward pressure on a plunger can comprise the combined weight of the fluid above the plunger, the plunger itself as well as the operating pressure of the sales line together with atmospheric pressure. Forces which exert an upward pressure on a plunger can comprise the pressure exerted by the gas in the casing. Frictional forces can also affect a plunger's movement. For example, once a plunger begins moving to the surface, friction between the tubing and the fluid load opposes plunger movement. Friction between the gas and tubing also slows an expansion of the gas. However, in a plunger installation, generally it is only the pressure and volume of gas in the tubing and/or casing annulus which serves as the motive force for bringing the fluid load and plunger to the surface. Once received at the surface, the plunger may be immediately dispatched back into the well or held until a subsequent plunger cycle time.
Plungers can be designed with various sidewall or sleeve geometries. Some examples are set forth in
As best shown in
As noted above, the lance member 130 includes an elongated rod 132 that is sized to extend through the central bore 122 of the sleeve member 110 when these members are united. In the illustrated embodiment, an upper end of the rod 132 comprises a standard American Petroleum Institute (API) fishing neck 148 design. When the upper and lower members are united, the fishing neck 148 extends beyond the top end of the sleeve member 110. If retrieval is required, a spring-loaded retriever is lowered into production tubing, falls over the API internal fishing and catches beneath a recessed annular landing of the fishing neck 148. This allows retrieving of the plunger if, and when, necessary. As the fishing neck 148 extends through and beyond the top end of the sleeve member 110 when the members are united, such retrieval allows for retrieving both members of the two-piece plunger 100.
The rod 130 is connected to an upper end of a body 134 of the lower lance member 130. The rod 132 has an outside cross-dimension/diameter that is sized to fit though the internal bore 122 of the sleeve 110 whereas the body 134 has a larger outside cross-dimension/diameter, which is sized to fit within a production tubing. A transition between the rod diameter and body diameter forms the shoulder 136, which is sized for conformal receipt within the end bore/socket 124 of the sleeve and against the sleeve seat 126. The rod 132 has a length that is greater than the length of the sleeve 110. In this regard, the rod extends out of the top open end 116 of the sleeve 110 when the sleeve and lance members are united. This permits both retrieval of the plunger using the fishing neck as described above and use of the top end of the rod 132 to disengage the sleeve 110 and lance member 130 upon the arrival of the united plunger in a surface unit/lubricator, as is more fully discussed herein.
In the illustrated embodiment, the body 134 of the lance member 130 also includes an internal bore 138, which extends from a bottom open end 140 upward into the body 134. In the present embodiment, an upper portion of the body 134 proximate to the shoulder 136 includes a plurality of ports 142. In the illustrated embodiment, the upper portion of the body sleeve includes six annular ports 142 disposed about its periphery. Other embodiments may use more or fewer ports. Further, such ports may have other geometrical configurations. The ports extend from the internal bore 138 to an outside surface of the body 134. In the illustrated embodiment, these ports 142 open through the shoulder 136 of the lance member 130. These ports 142 permit fluid to flow though the body 134, when the ports 142 are unimpeded. The ports 142 are impeded/closed when the lance member 130 is united with the sleeve member 110. That is, uniting the upper and lower members of the plunger results in the ports 142 being disposed within the end bore 124 of the sleeve member 110. That is, a solid sidewall of the end bore 124 blocks the ports 142 when the sleeve and lance members are united preventing fluid flow through the internal bore 138 and ports 142 of the lance portion 130.
In the embodiment of
When the united plunger 100 reaches the surface and enters the well head, the tip or top end of the rod 132 contacts an end surface 172 in the lubricator. See
To allow the lower portion 130 to reach the bottom of the well first, the sleeve 110 may be held for a time in the lubricator. After a predetermined time, the sleeve is released (e.g., by disengaging the mechanical catcher) to allow the sleeve 110 to fall out of the lubricator and to the bottom of the well. The duration that the sleeve 110 is maintained in the lubricator may permit the lance member enough time to reach the well bottom prior to release of the sleeve member. Alternatively, the sleeve member may be released prior to the lance member reaching the well bottom. In any embodiment, it is desirable that the sleeve and lance do not unite prior to both reaching the well bottom. Along these lines, the sleeve and lance member may be designed such that they fall at desired decent rates. For instance, the sleeve may be designed to descend at a slower rate than the lance member. In any embodiment, gas flows upwardly through the internal bore 122 of the sleeve 110 during its descent. See
It will be appreciated that multiple variations of the two piece plunger are possible and within the scope of the presented inventions. For instance, the rod of the lower portion may include a small axial (e.g., central) aperture that allows gas beneath the lower member to pass through the plunger thereby aerating fluid above the plunger similar to that disclosed in U.S. Pat. No. 7,513,301. Alternatively, the body of the lance member 130 may incorporate a plurality of individual bores of external channels rather than an internal bore. See
The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the inventions and/or aspects of the inventions to the forms disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the presented inventions. The embodiments described hereinabove are further intended to explain best modes known of practicing the inventions and to enable others skilled in the art to utilize the inventions in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the presented inventions. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.
The present application claims the benefit of the filing date of U.S. Provisional Application No. 62/060,872 having the filing date of Oct. 7, 2014, the entire contents of which is incorporated herein by reference.
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Number | Date | Country | |
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62060872 | Oct 2014 | US |