In one aspect, the present disclosure relates to devices that are energized using pressure variations. In another aspect, the present disclosure relates to methods for utilizing pressure variations to energize devices.
A variety of systems and devices may be utilized to carry out hydrocarbon-related operations. These operations may include the drilling and completion of wellbores, recovering hydrocarbons such as oil and gas, transporting hydrocarbons across pipelines and flow lines and processing hydrocarbons. One system used in connection with hydrocarbon-related operations is a chemical treatment system that adds one or more chemicals into a well.
In some wells, and particularly older wells, the lower sections of the production tubing and the well casing as well as the lower areas of the near wellbore formation can become blocked by corrosion, scale, paraffin deposits, deposits of petroleum distillates and other undesirable deposits. These deposits may hinder the production of gas from the well by plugging perforations made in the well casing, thereby preventing the flow of gas into the wellbore. To combat this problem, treatment chemicals may be introduced into the wellbore. These treatment chemicals can include such things as soap, acid, corrosion inhibitors, solvents for paraffin and petroleum distillates, stabilizers and other known treatment chemicals. A number of techniques have been employed to deliver treatment chemicals downhole, most of which require the use of a pump to transfer chemicals from a reservoir to the well head.
One method of treatment is to continuously pump a small amount of treatment chemical into the well during production. The treatment chemical falls to the bottom of the well, where it mixes with other fluids and is drawn up with the liquid lifted by a lifting device. This continuous treatment approach usually requires a conduit, known as a capillary string, which may be banded to the production tubing to deliver the chemical, which may be mixed with water, to the bottom of the well. Mixing chemicals with a small amount of produced fluids and continuously or periodically returning the resulting mixture to the wellbore is another treatment method. Still, another method of chemical delivery is a batch treatment that involves pumping liquid treatment chemicals down the borehole using on a dead space below the perforations to retain residual chemical for a period of time. Finally, as is described in more detail herein, another treatment method involves the application of chemicals directly below, onto, or into, a plunger, and then using the plunger to push or deliver the chemicals down the well.
Conventionally, these methods use a pump to convey a treatment chemical from a supply to its application site. In some configurations, the pumps are powered by electricity or a fuel. Such pumps, which can include electric-powered or diaphragm pumps, may utilize fuel generator sets that introduce or produce exhaust gases that may have a harmful effect on the local environment. Moreover, the operation of pumps utilizing electrical power or combustion may be undesirable in certain environments where electrical sparks or heat may ignite volatile materials. Further, because these pumps can operate for extended periods, electrical energy or fuel must be continuously supplied or replenished. Because hydrocarbon-related operations can occur in relatively remote geographical regions, maintaining a supply of power for these pumps may be burdensome. Thus, chemical treatment operations may be made more efficient if one or more of these pump operating characteristics were minimized or eliminated.
It should be appreciated that the operating characteristics such as undesirable emissions and on-going power supply demands may be associated with numerous other systems and devices used in a variety of hydrocarbon-related operations and also in operations unrelated to the oil and gas industry. Thus, such systems and devices may also be made more efficient if one or more of these operating characteristics were minimized or eliminated.
For detailed understanding of the present disclosure, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:
The present disclosure relates to a method and apparatus for transport of materials utilizing a pump mechanism driven by pressure changes, whether naturally occurring or controlled or induced, in an associated pressure source. The pressure swing pump stores energy from a high pressure peak to enable it to pump fluids, chemicals, lubricants, and the like into a positive pressure system. In one embodiment, the present disclosure relates to the delivery of treatment chemicals or fluids into a wellbore, flow line, vessel, gathering system, or gas or fluid transportation line. The present disclosure may introduce chemicals directly into the wellbore, production tubing, annulus between the production tubing and casing, down a capillary string to some point down the wellbore, or apply them below or to a plunger apparatus of the type used in artificial lift techniques. More specifically, the disclosure relates to a pump mechanism suitable for transporting treatment chemicals, fluids, and lubricants, and which is powered by changes in the pressure of a wellbore, vessel, or line to which the pump is fluidly connected. In one embodiment of the method of the present disclosure, the pump is used to draw treatment chemical, fluid, or lubricant, from a storage container, and thereafter pump the chemical, fluid, or lubricant, either directly into the wellbore, line or vessel or other apparatus. When the current disclosure is used to deliver materials for plunger application, the materials are applied below, onto, or inside the plunger for delivery by the plunger to the wellbore. At predetermined times when the plunger returns to the surface, additional treatment chemical can be applied below, onto, or inside the plunger before it descends the wellbore.
In another aspect, the present disclosure relates to a pump mechanism which is powered by the buildup of pressure that naturally occurs within a wellbore during periods when the wellhead is closed, or in a line or vessel when a valve is closed. Specifically, the pump uses the buildup of pressure to power one or more pistons which draw treatment chemicals from a supply into a chamber which may or may not be internal to the pump. Once a predetermined amount of treatment chemical has been drawn from the supply, the flow of treatment chemical is halted, and the pump is considered “charged.” Once charged, the pump can be manually discharged, set to “automatically” discharge fluids, chemicals, or lubricants, when the well, vessel, or line, pressure drops below charge pressure, or an automated system operating under predetermined parameters may then discharge the pump and release the treatment chemicals at an advantageous time so that the maximum benefit of the treatment chemicals is realized. For example, in a system where chemicals are applied directly into, onto, or under a plunger, an advantageous time for chemical release may be when the plunger has been retained by a plunger catcher within a manifold located at the wellhead.
In another aspect of the present disclosure, the pump mechanism may rely on the low pressure gas present in the well or low pressure flowing conditions in the flow line during periods when the wellhead or line is open to automatically “reset” the pump mechanism. The pump mechanism may also incorporate a spring, confined gas chamber, and compensation chamber which may be used alone or in combination during low pressure conditions to reset the pump.
In another aspect, the disclosure relates to a chemical application apparatus. The apparatus is a modification to manifold systems used in plunger lift operations. In this embodiment an applicator is positioned in the section of the manifold which receives the delivery system, e.g., plunger, plunger/dispenser apparatus, or plunger with attached chemical dispenser. The applicator is positioned such that it will be operatively adjacent to the receptacle portion of the plunger, plunger/dispenser or chemical dispenser attached to a plunger. The nature of the applicator can vary depending upon the form in which the chemical is utilized. Treatment chemical is provided to the applicator by the pump mechanism.
The disclosure also includes a method for using the pump mechanism to apply treatment chemicals as needed. In one aspect, this method involves catching the plunger or chemical delivery system in a manifold and using the pump to apply chemical into, onto, or below, the assembly without removing the assembly from the manifold.
The automated application of materials such as treatment chemicals in small amounts may be desirable. The current disclosure has the ability to automatically function with each pressure swing to deliver an adjustable amount of treatment chemical. Thus, the pumping mechanism of the present disclosure may also include one or more mechanisms for adjusting the amount of material drawn into the pump and thereafter delivered by limiting travel of the pistons enclosed within the pump.
It should be understood that examples of the more important features of the disclosure have been summarized rather broadly in order that detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto.
The present disclosure relates to methods for utilizing pressure variations as an energy source and devices employing such methods. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein.
The embodiments of systems and methods described herein may find use in any number of applications or environments wherein a source exhibiting pressure variations is available to operate as an energy source. In the oil and gas producing industry, for example, available variable pressure sources may be used to energize a pump mechanism that delivers materials such as treatment chemicals, fluids, and/or lubricants into a selected location such as a wellbore, a production flow line, a subsea flow line, a fluid or gas transportation line, a collection tank, etc. Such pumps may also be used to convey materials into equipment such as valves, gears, linkages and other equipment utilized in vessels, offshore facilities, surface and subsea gathering facilities, or transportation system. While embodiments of the present disclosure may find a wide range of uses, merely for clarity, the following detailed description refer to pump mechanisms used in the delivery of treatment chemicals to a gas well using a plunger lift technique. However, it is emphasized that such pump mechanisms are a non-limiting embodiment of the present disclosure and thus should not be taken as a limitation on the applicability of the teachings of the present disclosure to other situations.
For purposes of background, an abbreviated discussion of the plunger lift technique will be presented. Those skilled in the art will recognize that there are many variations which have been used in connection with the lift technique and system which is described below. The embodiments of the disclosure described may be modified for variations of the described lift system. Further, those skilled in the art will appreciate that the present disclosure need not be used to the exclusion of other chemical treatment methods. Costs and other considerations can result in the use of the present disclosure together with other treatment methods.
Referring to
Chemical application system 240 may also include a chemical storage reservoir 246 which is connected by conduit 390 to a pump mechanism 300. As will be discussed below, treatment chemical may be applied by pump mechanism 300 into the manifold 22 via an applicator 252. Applicator 252 can include a nozzle, an open end of conduit, an atomizer that sprays a chemical on an exterior of a plunger 20 or other such flow device. The selection of the specific applicator will be made taking into account the physical characteristics of the form of the treatment chemical.
In some embodiments, the chemical application system 240 does not utilize a plunger 20 as a carrier of treatment chemical. Rather, treatment chemical may be discharged directly into the wellbore 10. In other embodiments, the plunger 20 or other suitable chemical carrier may be extracted from manifold 22, inspected and recharged with the treatment chemical. Embodiments of the pump mechanisms described herein may be utilized in connection with each of these variants, or any combination of these variants.
Plunger 20 may be of any of the numerous designs which are known in the art or another delivery system as described herein. The plunger 20 provides a mechanical interface between the gas and the liquid present in the well and may be used to expel liquids such as water from the wellbore 10. During operation, the accumulation of liquids in the wellbore 10 may cause the pressure in the wellbore 10 to drop sufficiently to restrict or stop the flow of desired hydrocarbons. To restore wellbore pressure, the well is shut-in. To initiate a well shut in, controller 29 signals the plunger catcher 30 to pull back pin 244, thereby releasing the plunger 20 to fall toward the bottom of the well. As plunger 20 falls, fluid will pass around plunger 20 through a space left between plunger 20 and tubing 14 or through passageways (not shown) within plunger 20. Because the well is shut in, formation gases flowing into the wellbore 10 cause gas pressure to build in the well. When the well is opened, the built-up gas pressure will push plunger 20 and the liquid on top of the plunger 20 up tubing 14 to the surface.
It should be appreciated that the pressure in the well swings or cycles between a low pressure at a time proximate to well shut-in and a high pressure proximate to well opening. In this aspect, the well is illustrative of a source having pressure variations or fluctuations.
Referring now to
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Optionally, the line 360 may be in fluid communication with gas charging source 362 (FIG. 6)such as a methane or nitrogen supply. In this optional arrangement, check valve 365 may be added to prevent flow back of gas to the supply. In general, it may be preferable to maintain the pressure of the gas charging source at a level which is approximately equal to the pressure found in flow line 302. This embodiment may be preferable in applications wherein the pressure within the well is relatively constant and/or if opening and closing of the well is not automatic. Conversely, in applications wherein pressure within the well is not relatively constant, and/or opening and closing of the well is carried out by a timed schedule, then it may be beneficial to connect line 360 to a source of produced petroleum in a manner that low pressure may be conveyed to pump mechanism 300. Further, in some embodiments, a gas charging source 362 may be used in conjunction with a connection to the source of produced petroleum. In one embodiment, as the volume of low pressure chamber 430 decreases, the gas present in that chamber is forced back through line 360 and into flow line 302, maintaining the pressure in low pressure chamber 430 at the pressure of the flow line 302. Alternatively, check valve 365 may be provided in line 360 as shown in
Referring now to
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As shown in
Referring now to
As pressure in the wellbore increases, either through natural cycling or resulting from procedures performed on well 10 such as, for example, closing the well, the well transitions from a low pressure condition to a high pressure condition.
To initiate the delivery of the material in the treatment chemical chamber 440, the high pressure fluid in chamber 420 is vented via line 370. Thereafter, the solenoid valve 412 or other suitable flow control device is actuated by the control box 29 (
In one mode of operation, rather than allowing pressure to slowly build within high pressure gas chamber 420, which causes a relatively slow movement of pistons 320, 330 and connecting rod 410, a sudden exposure to the high pressure source may result in a relatively rapid movement of these elements. The relatively rapid movement may serve to create a more severe pressure imbalance between treatment chemical chamber 440 and chemical storage reservoir 246 (
Referring to
Referring to
In embodiments utilizing plunger 20, once treatment chemical has been discharged, control box 29 may be programmed to determine when it would be advantageous to close the well and to release plunger 20. It is known in the art to close a well, thereby creating a buildup of pressure within the formation, either by monitoring flow from the wellbore and closing the well once the flow drops below a predetermined level, or on a simple timed schedule. Regardless of the method used, once the well has been shut-in, control box 29 may then signal plunger catcher 30 to immediately release plunger 20, or to wait a predetermined period of time before releasing plunger 20. In arrangements utilizing a delay or a waiting period before releasing plunger 20, fluid have time to build up within the wellbore to slow the descent of plunger 20 and thereby reduce the potential for damage to plunger 20 that would be expected if it were allowed to fall unimpeded to the bottom of the wellbore. However, consideration must also be given to the fact that any fluid encountered by the plunger 20 during the decent may wash some treatment chemical from plunger 20. This may be an undesired result as it may be advantageous to deliver the entire load of treatment chemical to the bottom of the well. The timing of the release of plunger 20 may be specific to each application depending on the desired application, the treatment chemical used, its method of application, and the rate of flow of fluid into the well, however, those skilled in the art will recognize that well operators are knowledgeable of these variables and are able to make the determination as to when to release plunger 20 based on their experience in the industry and with the specific well.
As described above, plunger 20 and its associated apparatus may be omitted in favor of directly discharging treatment chemical down the wellbore 10. In such an arrangement, control box 29 determines when sufficient chemical has been drawn into treatment chemical chamber 440, and determines when it would be most advantageous to release the treatment chemical into the wellbore. In one embodiment, treatment chemical is released immediately after the well is shut in. This timing is advantageous for a number of reasons. First, when the well is shut in, there is no flow outward from the wellbore. Thus, treatment chemical released into the wellbore will be allowed sufficient time to flow to the bottom of the wellbore without the risk of the chemical being flushed out by the outward flow of petroleum or other fluids in the well. Second, releasing the treatment chemical returns pump mechanism 300 to its “uncharged” state. By releasing the chemical immediately upon shut in and returning the pump to the uncharged state, the pump is placed in position to begin the charging cycle again at the same time that the well is again beginning to build pressure.
Once treatment chemical has been discharged and in embodiments wherein low pressure chamber 430 is fluidly connected to a low pressure gas source such as flow line 302, this connection serves to tune the pump mechanism to the needs of the particular formation. Specifically, charging pump low pressure chamber 430 with a low pressure gas source such as flow line 302 provides a mechanism that can automatically tune itself to the needs of a particular application by varying the level of pressure in pump low pressure chamber 430. In so doing, pump mechanism 300 ensures continued operation regardless of any variation in the level of pressure in the formation which, because of the fluid connection between the formation and high pressure gas chamber 420, causes variations in the amount of pressure available to operate pump mechanism 300.
Unless actions are run from a simple timed schedule, the points at which a well is shut-in and opened are related to the pressure available in the formation as well as the pressure present in the flow line, which may be generally a relatively constant pressure. Typically, once a well has been shut-in, it will not be re-opened until the pressure in the formation has built to between 1.5 and 2.5 times the pressure in the flow line, although variations in this level may be possible. Thus, the maximum amount of pressure available to high pressure gas chamber 420 may range approximately between 1.5 and 2.5 times greater than the pressure present in pump low pressure chamber 430. It may be advantageous to balance high pressure gas chamber 420 against pump low pressure chamber 430 in this manner to ensure that pump mechanism 300 does not become biased in either the charged or uncharged states. In other words, if pump low pressure chamber 430 were not charged with low pressure gas, and instead mechanical means such as a spring 460 were used to return pistons 320, 330 and connecting rod 410 back to the “uncharged” state, the pressure available to fill high pressure gas chamber 420 may not be sufficient to overcome spring 460, which may then inhibit operation of the pump. By ensuring that high pressure gas chamber 420 need only work against the low pressure gas present in pump low pressure chamber 430, there is a greater likelihood that the pump will continue to function substantially independent of the pressures present in the formation and/or the flow line 360. As discussed above, in certain applications, such as where the level of pressure available in the formation is relatively constant, thereby eliminating or reducing the need for tuning, it may be advantageous to use a gas charging source 362 to provide a constant level of pressure to low pressure chamber 430.
In embodiments wherein low pressure gas chamber 430 is eliminated and the work of returning pump mechanism 300 to the uncharged state is left to spring 460 or to preferential weighting or orientation of pistons 320, 330 and connecting rod 410, pump mechanism 300 may nevertheless function, especially if used in applications where the pressure in the formation and the flow line are known and remain relatively constant. That is, in those applications, it is possible to select a spring 460, weights or an orientation which will be overcome by the pressure available to high pressure gas chamber 420 at a rate which is satisfactory to the operator.
As should be appreciated, pump mechanism 300 may be used to introduce treatment materials, such as chemicals, into a wellbore or flow line and may be energized by pressure swings or changes within the wellbore resulting from opening and shutting the wellhead or valve or choke or by other controlled variations in pressure. The pressure swings may also be naturally occurring pressure. The use of pressure swings or changes within the wellbore or flow line to power the pump reduces the need for external power sources, and reduces the environmental impact of the pump by reducing hazards and emissions from the pump and by reducing the footprint of the well. Moreover, the use of a pump which is not powered by the combustion of hydrocarbons or exhausting of hydrocarbons may reduce the risk of fire at the well. Also, in certain embodiments of the present disclosure, the pump is able to automatically adjust to changing pressure conditions within the well, thereby assuring continued operation in spite of variable operating conditions. Thus, embodiments of the current disclosure may be considered as economical due to the reduced need for additional equipment and reduced need for external power such as electrical power or fuel such as petroleum produced from the well.
Referring now to
Ports are provided in receptacle 70 to control flow through the receptacle 70. For example, one or more upper ports 94 and one or more lower ports 96 are used to allow gas and liquid to enter or leave the receptacle 70. Additionally, a valve 98 may be provided to further control fluid flow into and out of receptacle 70. In the illustrated embodiment, valve 98 is a flexible rubber sheet 100 having a dimension sufficient to cover lower ports 96. Valve 98 is held in place by a retaining plug 102 which can extend through an opening 104 in the bottom of the member 68. The purpose of valve 98 is to either restrict or close off the flow of liquid through lower ports 96 as the plunger 20 drops. As the plunger 20 drops in the tubing, the flexible sheet 100 will be pushed against the bottom of the member 68. This will either completely seal or partially seal off ports 96. The purpose of valve 98 is to minimize or prevent the flow of fluid through receptacle 70 while the system drops in the tubing. This will prevent or minimize the washing of chemicals out of the receptacle as the chemical dispenser 65 passes through the fluid above the stop of the tubing. Once the delivery system 64 comes to rest on the stop, flexible sheet 100 will fall away from the bottom of member 68 and to a second position 101 (shown in phantom), because there is no force pushing the flexible sheet 100 against the bottom of member 68. This will allow liquid to enter receptacle 70 and leach the treatment chemical 72 out of receptacle 70.
Chemical delivery system may include a threaded surface 106 on the bottom of head 66 to engage a threaded surface 108 on member 68. This allows member 68 to be removed from head 66 for the insertion of chemicals into the receptacle 70. Alternatively, head 66 and member 68 can be one piece and an opening 110 provided through which chemicals can be inserted into the receptacle 70.
Yet another type of plunger suitable for use in connection with embodiments of the present disclosure include a bypass plunger (not shown). One suitable bypass plunger includes a bypass valve. The valve is open during a downstroke of the bypass plunger to reduce travel time to a bottom of a well. During the upstroke of the bypass plunger, a pressure differential across the valve keeps the valve closed to assist in pushing fluids to the surface. A spring in the valve opens the valve when the pressure differential decreases to below a selected value.
Referring now
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Referring now to
In a manner similar to that previously described, the pump 300 may be energized using pressure variations caused by the activation and deactivation of the flow control device 702. In one embodiment, pump 300 includes a high pressure gas chamber 420 in fluid communication with the fluid conduit 700 at or near point 704 via line 370, a low pressure chamber 430 in fluid communication with the fluid conduit 700 at or near point 706 via line 360, and a treatment chemical chamber 440 in fluid communication with the fluid conduit 700 via line 400. Of course, a low pressure source 362 (
Referring now to
In a manner similar to that previously described, the pump 300 that may be energized using pressure variations caused by the accumulation and displacement of the fluid 804. The accumulated fluid is sometimes referred to as a fluid slug. For gas flow, liquid slugs may form at valleys or low points in a conduit whereas for liquid flow, gas slugs may develop at peaks high points in a conduit. The various elements of the pump 300 have been previously discussed and will not be repeated. In one embodiment, pump 300 includes a high pressure gas chamber 420 in fluid communication with the flowline 800 at or near point 806 via line 370, a low pressure chamber 430 in fluid communication with the flowline 800 at or near point 808 via line 360, and a treatment chemical chamber 440 in fluid communication with the flowline 800 via line 400. Of course, a low pressure source 362 (
From the above, it should be appreciated that embodiments of the present disclosure may utilize a pump mechanism that is driven by variations in the pressure found in the pressurized sources to which it is connected. The pump mechanism may be connected to and driven by any one of a number of gaseous or fluid sources so long as the source or sources to which it is connected experience variations in pressure, whether such variations are naturally occurring or controlled. It should also be appreciated that the pump may deliver a material into a pressurized environment. That is, flowlines or wells may have an operating pressure greater than atmospheric pressure. Nevertheless, embodiments of pumps can deliver a material such as a liquid or pellet into the pressurized environment by making use of pressure variations as described above.
Further, it should be understood that
In
In
Embodiments of the present disclosure may be advantageously applied in the area of petroleum production and to wells which require the periodic application of chemicals used to treat the well or flow line. The pump mechanisms of the present disclosure may be used in any number of applications in and around the petroleum producing industry, such as for example, but without limitation, the injection of chemicals, fluids and/or lubricants into a wellhead, flow line, vessel, gathering or transportation system. Moreover, embodiments of the present disclosure may be utilized in a variety of hydrocarbon-producing wells, such as oil and/or gas producing wells, generally without regard to production levels or well geometry, including stripper wells, deviated wells, and wells utilizing artificial lift techniques. As described, the pump mechanism may operate by utilizing pressure changes found in a wellbore, but may also take advantage of pressure differentials and pressure swings across, for example, valves.
Although much of the above-descriptions referred to vertical gas wells and wells using plunger lift technology, those conditions should not be taken as a limitation on the applicability of the present disclosure, and any reference to the term “well” should be understood as applying to the broadest applicable range of physical, geological, and/or production characteristics, including all apparatus appurtenant to the well such as all production equipment, vessels, and transportation lines. Furthermore, it should be understood that although embodiments of the present disclosure has been described in relation to a single pumping mechanism delivering a single treatment chemical, alternate embodiments in which multiple pumping mechanisms deliver multiple treatment chemicals in connection with a single well are possible. For example, in some wells, it may be desirable to treat paraffin deposits located at a relatively shallow depth within well 10 with a paraffin inhibitor, while also treating corrosion located at greater depths within well 10 with a corrosion inhibitor.
Although the disclosure has been disclosed and described in relation to its preferred embodiments with a certain degree of particularity, it is understood that the present disclosure of some preferred forms is only by way of example and that numerous changes in the details of construction and operation and in the combination and arrangements of parts may be resorted to without departing from the scope of the disclosure as claimed here.
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Number | Date | Country | |
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20080308270 A1 | Dec 2008 | US |