Ventless gas-driven pumping system

Abstract

A ventless gas-driven pumping system controlled via a plurality of pneumatic valves and associated switches, for driving a diversity of process pumps at a natural gas well site. The ventless pumping system is readily interconnected with any gas pipeline location and uses flowing well gas and consequent differential pressure to drive a plurality of pumps and related pneumatic controls exclusively using a continuous self-generated air supply. Only self-generated air and no well gas is vented into the atmosphere during pumping operations.

Description

IN THE DRAWINGS

The file of this patent contains at least one drawing executed in color. Copies of this patent with the color drawing (FIG. 1) will be provided by the Patent and Trademark Office upon request and payment of the necessary fee.

FIG. 1 depicts a schematic diagram of the components and associated functionality of the preferred embodiment of the present invention.

FIG. 2 depicts a front perspective view of a generalized representative embodiment of the present invention

FIG. 3 depicts a side perspective view of the embodiment depicted in FIG. 2.

DETAILED DESCRIPTION

FIGS. 1-3 collectively depict the pumping system contemplated under the present invention. In particular, FIG. 1 depicts a schematic of the preferred embodiment of the present invention interconnected with a typical natural gas production well scenario as contemplated hereunder. FIGS. 2 and 3 generally depict a representative physical configuration of the various components that comprise a pumping system embodiment. It should be understood, of course, that arrangements of physical components and the like vary substantially as a function of well site logistics, diversity of components selected to constitute an embodiment, and process pumps being driven. Accordingly, other embodiments hereof may indeed have components configured and arranged differently from that which is depicted in FIGS. 2 and 3. Notwithstanding, the teachings of the present invention should be clearly understood from the schematic representation shown in FIG. 1.

As will become clear to those skilled in the art, interdependent flow paths or circuits are shown for each of well gas, glycol, air, chemical, and gas-operated diaphragm (“AOD”) pump. It will be understood that AOD pump may be operated by air or another suitable gas. Each of these circuits is rendered in a different color to clearly identify its functionality and its interrelationship with the other circuits that afford synergy to the embodiments of the ventless pumping systems contemplated herein. The well gas circuit is colored red; the glycol circuit is colored blue; the air supply circuit is colored green; the chemical circuit is colored lavender; and the AOD supply circuit is colored brown.

Drive cylinder 100 operates a dual-acting glycol piston pump 200 and a beam chemical injection pump 400. In a manner known in the art, glycol pump 100 is used to circulate hot glycol through heat exchanger tubes in a process loop including the wellhead, a gas-liquid separator, and a water storage tank (to prevent freezing); and then, the hot glycol is circulated to the glycol heater and recycled back to the glycol pump 200. The chemical injection pump 400 is used to pump methanol or the like down the well annulus to help prevent formation of hydrates in the well.

As will become evident to those skilled in the art, prerequisite differential pressure for operating an embodiment of the instant pumping system is generated by differential pressure control valve 190. More particularly, differential pressure (“ΔP”) control valve 190 is preferably interconnected with flowline 180 in order to generate a pressure differential between well gas inlet 140 and well gas outlet 145. It will be understood that the pressure at well gas inlet 140 is higher than the pressure at well gas outlet 145.

Pneumatically-controlled cycling valve 310 supplies higher pressure inlet well gas first to one side of dual-acting drive cylinder 100, thereby pushing drive cylinder piston 105 in one direction while simultaneously exhausting lower pressure well gas out of the other, opposite side thereof to well gas outlet 145, and then, in turn, back into flowline 180.

It should be understood that, when drive cylinder piston 105 reaches the end of its stroke, drive cylinder piston rod 110 mechanically actuates a pneumatic switching valve of pair of pneumatic switching valves 305 which, in turn, actuates cycling valve 310. The higher pressure inlet well gas is then switched to flow to the other, opposite side of drive cylinder 100, thereby pushing drive cylinder piston 105 back in the opposite direction. Simultaneously, lower pressure well gas is expelled out the other side of drive cylinder 100 to well gas outlet 145 and then back into flowline 180.

It will be appreciated that, when drive cylinder piston 105 reaches the end of its current stroke, drive cylinder piston rod 110 mechanically actuates another pneumatic switching valve of pair of pneumatic switching valves 305. The present invention contemplates that this valve-switching aspect of each pumping cycle continually repeats itself during pumping operations as herein described.

Referring now collectively to FIGS. 1-3, it will be observed that pair of drive cylinder piston rods 110 extend from both ends of drive cylinder 100. Pair of piston rods 110 mechanically drive a plurality of process pumps—illustrated with glycol pump 200 and chemical injection pump 400. In this exemplary embodiment, in particular, glycol pump 200 corresponds to a conventional dual acting piston pump having four check valves 205; and chemical injection pump 400 corresponds to a conventional beam actuated pump. As will be understood by those skilled in the art, piston rods are inherently sealed within its cylinder commensurate with its normal performance. The prerequisite drive cylinder force available to operate this plurality of pumps may be calculated by the well known formula shown in equation 1:

F=(ΔP×A)·  Friction (1)

wherein F corresponds to the drive cylinder force; ΔP corresponds to the differential pressure; A corresponds to the area of the piston less the concentric area of the piston rod; and Friction corresponds to the internal friction within the drive cylinder. Those skilled in the art will understand that this contemplated pressure differential varies from one gas well application to another; moreover, friction considerations are empirically guesstimated in the field.

The pumping system of the present invention is controlled by pneumatic valves and switches. It will be appreciated that embodiments of the instant pumping system self-generate low-pressure air supply for actuating pneumatic valves and switches. Thus, drive cylinder 100 drives air cylinder 300 which supplies air to air bottle 315 or other suitable container, and interconnected air lines. The air pressure within air bottle 315 is regulated by adjustable vent valve 320.

According to the present invention, at pumping system start-up, a very small, virtually insignificant amount of low-pressure inlet well gas is supplied to the control system through gas regulator 150 and shuttle valve 325. This small amount of low-pressure inlet well gas is necessary only for operating pair of switching valves 305 and cycling valve 310 for a short period of time in order to begin the stroking of drive cylinder 100 which drives air cylinder 300 which, in turn, supplies air to the to air bottle or reservoir 315 and interconnected air lines.

To illustrate the infinitesimal amount of low-pressure well gas that is actually consumed and vented during this limited start-up phase of pumping system operation, it has empirically been found that a mere 30-40 cubic inches of gas is consumed which is approximately 2% of one cubic foot thereof which is vented into the atmosphere. It will be appreciated that as one or two cylinder drive strokes are effectuated as herein described, approximately only a few seconds have elapsed. Only intended to be a representative illustration, if typical drive stroke frequency were assumed to be about 10 strokes per minute, taken as being in the range of 8-15 strokes per minute, then there would be one stroke nominally about every 6 seconds. Ergo, system startup as contemplated hereunder has a very short duration with an infinitesimal loss of well gas. It should be evident that this start-up phase has no significant impact upon the ventless aspect of the present invention.

It will be understood that the air pressure inside air container 315 is preferably regulated by adjustable vent valve 320. It has been found that adjustable vent valve 320 should preferably be set to sustain the air pressure in air bottle 315 in the range of about 10-15 psi. Similarly, gas regulator 150 should preferably be set to supply well gas in the range of about 5-10 psi. Then, when the air supply in air bottle 315 reaches a pressure slightly higher than the pressure of the well gas coming from gas regulator 150—preferably after approximately one or two drive cylinder strokes and enough prerequisite air has been pumped-shuttle valve 325 switches off the well gas from gas regulator 150 and then switches on the supply air from air bottle 315.

It should be evident that the pumping system embodiment then continues operating using only its self-generated air supply to actuate pair of switching valves 305 and cycling valve 310. Therefore, during start-up, unlike conventional pumping systems known in the art, embodiments taught by the present invention vent a very small amount of low pressure well gas to the ambient. But, after a short start-up period of approximately one drive cylinder stroke, pumping system embodiments hereof use only self-generated air to actuate pair of switching valves 305 and cycling valve 310. Accordingly, during normal operations, a pumping system embodiment vents only air and no well gas to the atmosphere; hence, the present invention contemplates and teaches a substantially “ventless” gas-driven pumping system.

It has been found that, if gas flow from a well has been interrupted, differential pressure control valve 190 may be unable to generate a sufficient differential pressure between well gas inlet 140 and well gas outlet 145 prerequisite to actuate drive cylinder 100. For instance, an interruption in the gas flow from the well may be due to the well loading-up with water, plugging-up due to hydrate formation, valve closure or otherwise. To cope with such flow interruptions, ventless gas driven pumping system embodiments should preferably be configured with a backup system affording continued pumping of liquid or gas product, e.g., glycol, until such gas flow interruption has been remedied.

Thus, for an embodiment pumping glycol, a backup system of the present invention would comprise glycol pressure switch 500 and gas-operated diaphragm pump (“AOD” pump) 510. As will be appreciated by those skilled in the art, when there is an interruption in well gas flow, contemplated ventless gas-driven pumping system embodiments will ordinarily be unable to generate adequate glycol discharge pressure. However, if glycol pressure switch 500 detects a low glycol discharge pressure condition, indicative of a gas flow interruption, it will switch on low pressure AOD supply gas whereupon AOD pump 510 will be activated and begin pumping glycol. Then, when normal well gas flow resumes, ventless gas-driven pumping system embodiments will begin generating adequate glycol discharge pressure, and the backup system will no longer need to be activated. Accordingly, glycol pressure switch 500 will then switch off the low pressure AOD supply gas to AOD pump 510. And, the ventless gas-driven pumping system will resume normal operation as contemplated hereunder.

It will be appreciated by those skilled in the art that a ventless gas-driven pumping system contemplated hereunder can be connected into any gas pipeline in any flowing process gas stream. Such a ventless pumping system affords a convenient and efficient replacement that eliminates pumping systems that inherently exhaust well gas to the atmosphere. As a result of this pumping system replacement taught by the present invention, wasting of valuable well gas, polluting the atmosphere, and creating safety and health hazards are essentially terminated. It has been found that a common application of such pumping system replacement is especially advantageous at or near natural gas production well sites where electrical power is typically unavailable.

The natural gas production well applications depicted in FIGS. 1-3 generally illustrate how the drive cylinder of the present invention operates a dual-acting glycol piston pump and a beam chemical pump, wherein the glycol pump circulates hot glycol throughout heat exchanger tubes—with process loop including the wellhead, gas-liquid separator, water storage tank, glycol heater, and cycle back to the glycol pump. The chemical pump is used to pump methanol down the well annulus to help prevent formation of hydrates in the well.

Other potential applications of the present invention include interconnection with any gas processing facility to enable replacement of gas-drive pumps and/or to enable replacement of air supply for pneumatic controllers, actuators and level controllers. The ventless gas driven pumping system pays for itself severalfold. As a first example, since the ventless gas-driven pumping system fundamentally does not vent valuable well gas, there is a savings equal to the value of the well gas that would be currently vented to atmosphere by conventional gas-driven pumps. As a second example, since a ventless gas-driven pumping system does not vent well gas pollutants or the like, there is an environmental beneficial value that can be calculated based upon particular circumstances.

Indeed, it will be readily appreciated that such environmental value not only transcends affording tangible benefits—as in the instance of carbon credits—but also affords intangible benefits—as in the instance of substantially enhanced good will and concomitant public image. Since ventless gas-driven pumping system embodiments inherently do not vent flammable and harmful well gas, such pumping sites are significantly safer and healthier than conventional gas well sites.

Other variations and modifications will, of course, become apparent from a consideration of the apparatus and concomitant methodology hereinbefore described and depicted. Accordingly, it should be clearly understood that the present invention is not intended to be limited by the particular features and structures hereinbefore described and depicted in the accompanying drawings, but that the present invention is to be measured by the scope of the appended claims herein.

Claims

1. A ventless pumping system for operating a plurality of process pumps with said: ventless pumping system interconnected with a flowline having well gas flow therein, said ventless pumping system comprising: a differential pressure control valve member connected into said flowline to generate a pressure differential between an inlet member and an outlet member, with said well gas flow through said inlet member flowing at higher pressure than said well gas flow at said outlet member;a cycling valve member for continuously directing said high pressure well gas alternately to each side of a drive cylinder member and for simultaneously directing said lower pressure well gas alternatively to each opposite side of said drive cylinder member, while recycling said lower pressure well gas to said flowline without any venting thereof into the atmosphere;said recycling valve member alternately redirecting said high pressure well gas to either side of said drive cylinder member;said high pressure well gas supplied through said cycling valve member to said drive cylinder member for mechanically actuating, in turn, each of a pair of switching valve members;each switching valve member of said pair of switching valve members disposed at an opposite end of said drive cylinder member adjacent a sealed drive piston rod of a pair of sealed drive piston rod members, with each said sealed drive piston rod member extending outwardly from a corresponding end of said drive cylinder member;a piston member disposed annularly of said drive cylinder member and axially containing said pair of sealed drive cylinder piston rod members;said pair of sealed drive cylinder piston rod members driving an interconnected air cylinder member for self-generating low pressure air to actuate said pair of switching valve members and said cycling valve member; andsaid plurality of process pumps interconnected with said pair of sealed drive cylinder piston rod members and being powered thereby.

2. The ventless pumping system recited in claim 1, wherein a shuttle valve member receives a small startup amount of said well gas at low pressure from a gas regulator member interconnected with said flowline and supplies said small startup amount thereof to air lines interconnected with and operating said pair of switching valve members and said cycling valve member for a short time until stroking of said drive cylinder piston member commences.

3. The ventless pumping system recited in claim 2, wherein said shuttle valve deactivates said well gas flow from said gas regulator member once said self-generated air supply pressure exceeds said pressure of said well gas flow from said gas regulator member, wherein said self-generated air supply commences controlling said pair of switching valve members and said cycling valve member.

4. The ventless pumping system recited in claim 1, wherein said self-generated low pressure air is received by an air bottle member and said interconnected air lines, with an adjustable vent valve member sustaining said low pressure in said air bottle and said interconnected air lines by venting any excess of said self-generated air into the atmosphere.

5. The ventless pumping system recited in claim 4, wherein said self-generated low pressure air is directed to an air-actuated cylinder disposed at an end of said cycling valve member by said switching valve member and urges said cycling valve member to cycle from a first position to a second position and then venting said low pressure self-generated air into the atmosphere.

6. The ventless pumping system recited in claim 5, wherein said self-generated low pressure air flow and said pair of switching valve members cause said cycling valve member to continuously cycle from said first position to said second position, and vice versa, to sustain said driving of said drive cylinder member and, in turn, to sustain said driving of said plurality of process pumps.

7. The ventless pumping system recited in claim 1, wherein said drive cylinder member comprises a piston member disposed annularly thereof and with each of said pair of switching valve members interconnected at an opposite end thereof.

8. The ventless pumping system recited in claim 7, wherein one of said pair of said switching valve members is urged by said adjacent sealed drive cylinder piston rod member and said switching valve member actuates said cycling valve, directing said high pressure well gas to a first end of said drive cylinder member, and simultaneously directing said lower pressure well gas to a second, opposite end thereof, and upon completing its stroke, said other sealed piston rod member mechanically actuating said adjacent switching valve member which, in turn, actuates said cycling valve member for redirecting said high pressure well gas to said second end of said drive cylinder member and simultaneously redirecting said lower pressure well gas to said first end thereof.

9. The ventless pumping system recited in claim 8, wherein simultaneously with said piston member actuating said cycling valve member, expelling said well gas at lower pressure from the other, opposite end of said drive cylinder member to said well gas outlet and back into said flowline.

10. The ventless pumping system recited in claim 1, wherein at least one process pump of said plurality of process pumps includes a low discharge pressure switch member indicating an interruption of normal, adequate fluid discharge pressure, and a gas-operated diaphragm pump member is activated until sufficient pressure is generated to sustain normal flow of said process pump fluid.

11. The ventless pumping system recited in claim 10, wherein said gas-operated diaphragm pump member is deactivated when said normal process pump flow has been restored.