Patent application title: Bailer stimulation production unit
Charles Chester Irwin, Jr. (Columbus, TX, US)
Harley Mccorcle (Gonzales, TX, US)
Delton W. Bishop (Luling, TX, US)
Lift Tech LLC
IPC8 Class: AE21B4300FI
Class name: Wells processes producing the well
Publication date: 2012-04-19
Patent application number: 20120090851
An apparatus and process for gas, oil, and other fluid production using
bailer technology with stimulation to enhance production. An enclosed
apparatus and process for removing gas, oil, and/or other fluids from a
well while reducing environmental impact. A novel divalve for
simultaneously closing a conainer and dumping liquids into it.
1. An oil and gas recovery system comprising: a well casing connecting a
subterranean reservoir with a well head, a collection housing docked to
said well head with an open bottom surrounded by a sealing flange, a
bailer capable of entering through said open bottom of said collection
housing and being housed therein ("home") with a canister, a means for
loading liquids from said reservoir into said canister, and a bivalve
with a seal plate assembly that includes a seal plate that seals against
said sealing flange, thereby closing said bottom of said collection
housing and simultaneously unseals from the bottom of said bailer,
thereby permitting liquids from said canister to unload into said
collection housing without exposing said liquids to the environment, a
winch and cable deployed over a pulley and attached to said bailer for
lowering said bailer from said collection housing through said casing
into said reservoir, retaining said bailer as said canister fills with
said reservoir liquids, and lifting said bailer from said reservoir into
said collection housing, a stimulation means for stimulating production
of fluids from said reservoir, means for uninterrupted production of
natural gas from said reservoir without exposing said gas to the
environment, and a means for transferring said fluids from said
collection housing to storage facilities or pipelines.
2. The recovery system of claim 1 wherein said collection housing and said bailer are cylindrical, the ID of said collection housing is approximately ten to twenty percent less than the OD of said bailer, the length of said bailer is sufficiently less than the length of said collection housing that said bailer fits into said collection housing in its "home" for unloading, and the top of said housing has an opening for said cable.
3. The recovery system of claim 1 wherein said recovery system includes a means for determining the depth of the surface of said reservoir liquids, and a programmable logic controller for controlling the fill, empty, and travel times for said bailer.
4. The recovery system of claim 3 wherein said means for determining reservoir liquid depth is a scale temporarily attached to said cable above said collection housing.
5. The recovery system of claim 1 wherein said stimulation means is a plurality of disks suspended on a rod from said bailer.
6. The recovery system of claim 1 wherein said stimulation means releases gases from reservoir fluids, creates additional turbulence and/or to creates waves in said reservoir.
7. The recovery system of claim 6 wherein the shape of said disks may be spherical, flat, or cup-shaped.
8. The recovery system of claim 1 wherein said internal means for uninterrupted production of natural gas includes a spring-loaded check valve centered over an opening in said seal plate.
9. The recovery system of claim 1 wherein said seal plate is flat and circular.
10. The recovery system of claim 1 wherein said seal plate is hemispherical.
11. The recovery system of claim 1 wherein said seal plate assembly includes said seal plate, a retaining spring, and a retaining plate.
12. The recovery system of claim 11 wherein said bivalve dumps liquid from said canister into said collection housing when said pulley compresses said retaining spring against said retaining plate, thereby causing said seal plate to simultaneously seal to said sealing flange and unseal from said bailer.
13. A process by which natural gas is produced and stored comprising: the upward passage of natural gas from a subterranean reservoir into a well casing, the continued upward passage of said natural gas through an opening in a steal plate under a bailer canister, a check valve under said bailer canister when the pressure of said gas opens said valve, fluids in said bailer, and vent holes in the top of said canister, into a collection housing, and through outlet means to a storage facility or pipeline.
14. A process by which oil is produced and stored comprising: lowering a bailer into a subterranean reservoir, stimulating fluids in said reservoir, filling said bailer with oil from said reservoir, lifting said bailer into its "home" position in a collection housing, sealing a sealing plate to a sealing flange, thereby closing the bottom of said housing, simultaneously unsealing the bottom of said bailer, thereby unloading said oil from said bailer into said collection housing, transferring said oil from said collection housing to a storage facility or pipeline.
15. An apparatus for increasing production of oil from a subterranean reservoir comprising: a plurality of stimulators, a means of immersing said stimulators into said reservoir near a wellbore, thereby creating turbulence and waves in standing fluids in said reservoir, and a means of retrieving said stimulators from said reservoir.
16. The apparatus in claim 15 wherein said stimulators may be flat disks, oval disks, spherical balls, or a combination thereof.
17. The apparatus in claim 15 wherein said stimulators are flat, cupped-shaped disks that increase production by facilitating the removal of solid particles from said standing fluids.
18. The apparatus in claim 15 wherein said stimulators facilitate the removal of solid particles from said wellbore.
19. The apparatus in claim 15 wherein said stimulators increase production by facilitating the flow of reservoir hydrocarbons to said wellbore.
20. The apparatus in claim 15 wherein said stimulators are attached to a rod attached to the bottom of a bailer in a bailer fluid production system and said immersing and retrieval systems are said bailer fluid production system.
21. A process for increasing production of oil from a subterranean reservoir using a bailer recovery system comprising: lowering a bailer with a plurality of stimulators attached underneath said bailer into a well casing, immersing said stimulators into said reservoir, creating turbulence and waves in standing fluids in said reservoir, and retrieving said stimulators from said reservoir.
22. A production system for uninterrupted production of natural gas from a subterranean reservoir comprising: a well casing connecting said reservoir with a cylindrical collection housing, a cylindrical bailer with an OD approximately eighty to ninety percent of the ID of said collection housing, a check valve in the bottom of said bailer providing gas communication between said reservoir and a canister in said bailer when the pressure of said natural gas from said reservoir is sufficient to open said valve, a plurality of vent holes in the top of said canister providing gas communication between said canister and a wellhead collection housing, and an outlet means in said collection housing for transferring said natural gas to a storage facility or pipeline.
23. A process for uninterrupted production of oil and natural gas from an oil and gas well using a bailer recovery system comprising: venting said natural gas around an empty bailer and through a check valve and vent holes in said bailer while lowering said bailer through a wellbore to the surface of a subterranean reservoir, venting said natural gas through said wellbore while immersing said bailer into said reservoir, venting said natural gas through said wellbore as a canister in said bailer fills with said oil from said reservoir, venting said natural gas around a full bailer while retrieving said bailer from said reservoir into a collection housing, venting said natural gas around a full bailer in said collection housing, venting said natural gas around said bailer as said oil empties from said canister into said collection housing, venting said natural gas around said bailer and through said check valve and said vent holes while said oil is transferred from said collection housing to an oil storage facility or a pipeline, transferring said natural gas and said oil from said collection housing to storage facilities or pipelines, and repeating said production steps for continued fluid production.
24. A bivalve for unloading liquid from a vessel comprising: a collection housing with an opening through which said vessel may enter and exit, a seal flange, and an outlet means for transferring said liquids to a storage facility or pipeline, a means for moving said vessel into and out of said collection housing, and a seal plate that seals to said seal plate, thereby closing said collection housing and unseals from the bottom of said vessel, thereby opening said vessel and unloading said liquid from said vessel into said collection housing when said vessel is "home" inside said collection housing.
25. The bivalve of claim 24 wherein said vessel enters and exits said collection housing through an opening in the bottom of said collection housing which is sealed closed by said seal plate when said vessel is "home" inside said collection housing.
26. The bivalve of claim 25 wherein said vessel and housing are cylindrical, a winch and cable pull said vessel into said collection housing, said seal plate seals against a sealing flange in said bottom of said collection housing, said winch and cable compresses said vessel against a spring as said vessel is pulled into said collection housing, and said vessel separates from said seal plate, thereby creating an opening for said liquid in said vessel to flow into said collection housing, and thence to a storage facility or pipeline via an outlet in said collection housing.
27. The bivalve of claim 24 wherein said vessel is a bailer used to produce oil from a well.
28. The bivalve of claim 27 used to release oil from said bailer.
29. A process for emptying liquid from a vessel into a collection housing comprising: moving said vessel up through an opening in the base of said collection housing, sealing said opening, unsealing said seal plate from the bottom of said vessel, thereby creating an opening in the base of said vessel, unloading said liquid from said vessel into said collection housing, transferring said liquid from said housing into a storage facility or pipeline, sealing said seal plate to the bottom of said vessel, unsealing said seal plate from said opening, thereby reopening said collection housing, and moving said vessel down through said housing opening.
30. The process of claim 29 wherein said opening in said collection housing is sealed with a seal plate sealed to a sealing flange in said bottom of said housing and said bottom of said vessel is sealed with said seal plate sealed to said bottom of said vessel.
31. The process of claim 29 wherein said seal plate is a flat plate that seals under said opening in said bottom of said collection housing.
32. The process of claim 29 wherein said seal plate is a hemispherical seal that seals against the perimeter of said opening in said bottom of said collection housing.
FIELD OF INVENTION
 The present invention relates to an inexpensive method for recovering gas, water, crude oil, and/or other fluids using a bailer lift system to transport fluids to the surface. The invention further relates to recovery systems that may be integrated in a single capture and unload component. The invention further relates to production systems with reduced environmental impact based on utilization of integrated components and processes at the wellhead. The invention further relates to problems associated with the aging process of the well and subterranean formation. The invention further relates to the prevention of decreased flow from well annulus due to corrosion, formation build up, and other natural downhole processes. The invention further relates to more cost-effective fluid extraction from marginal wells as compared to purchase, maintenance, and operating costs of conventional lift systems. The invention also relates to fluid bearing subterranean formation stimulation to improve the flow of formation fluid to the wellbore. The relation also relates to simultaneous valving operations for dumping liquids.
BACKGROUND OF THE INVENTION
 The novelty of BAILER STIMULATION PRODUCTION UNIT lies in its cost-effective, simple, and environmentally safe operation, and in its ability to enhance production from wells that respond to stimulation. There is nothing new about bailer technology; it has been employed by man since the first uses of containers to hold water while moving it to higher elevations. There is nothing new about using bailer technology to pump fluids from subterranean reservoirs to wellheads; man has been doing that since long before Samuel Woodworth wrote about "the moss-covered bucket which hung in the well" in Scituate, Mass. two hundred years ago. Since then numerous patents have been issued for bailer pumps for marginal oil wells. Two competing goals for such systems is reduced costs versus safety.
 Some prior art bailer technology uses a pump or compressed air to unload production fluids from a bailer (See, for example, Strickland, U.S. Pat. No. 6,464,012 and Eggleston, U.S. Pat. No. 7,007,751). However, both processes are expensive, unreliable and environmentally hazardous due to seals that must be maintained in order for them to be functional. Moreover, air injected into a hydrocarbon mixture is extremely dangerous. Conventional pumping units used in low fluid wells have the risk of pump damage and damage to the well annulus. Pulling machines, hot oilers, steamers, and chemicals are extremely unfriendly to rods, tubing, downhole pumps, etc. Therefore, the processes inside the well annulus pose a potentially hazardous environmental impact because the corrosive environment inside the well annulus attacks ferrous materials and deposits them into the fluids and formations. Moreover, this corrosive environment requires expensive and labor intensive maintenance of conventional pump wells including rod and tubing maintenance, costs to fish parts and repair and clean them, downtime for repairs, and removal of paraffin and iron sulfide disposals.
 Most prior art bailer pump systems use gravity to unload fluids from the bailer. An important advantage of gravity unloading is that it is cheap--nature does the work. A disadvantage is that it may expose the environment to toxic fluids and/or risk spillage and waste. For example, Klaeger, U.S. Pat. No. 4,086,035 exposes recovered oil to the open atmosphere. On the other hand, Alexander, U.S. Pat. No. 4,368,909 temporarily seals the wellhead closed to prevent the escape of fluids such as natural gas during unloading. However, sealing the wellhead during unloading may result in dangerous pressure buildup which must be released before the bailer commences the next retrieval cycle. Recent prior art is driven by the need for less and less expensive extraction costs and dwindling reservoir levels and may achieve cheaper production at the expense of environmental safety. For example, Grant, U.S. Pat. No. 7,481,271 discloses an extraction system that produces oil from stripper wells cheaply, but the extraction container is emptied by tilting it over a funnel connected to a storage tank.
 The present invention uses gravity flow unloading in a novel way. It not only produces oil from marginal wells inexpensively, it does so without releasing toxic fluids to the atmosphere during unloading, and without sealing the wellhead and interrupting production.
 Feedback means for controlling the timing of bailer extraction systems has come a long way. The primary variable in the timing of bailer extraction systems is the distance between the wellhead and the liquid surface of the subterranean reservoir. Sensing devices commonly used today can determine the depth of the top of the liquid surface, and even the depth of the oil or oil/water interface in the reservoir. Senghaas, U.S. Pat. No. 4,516,911 teaches the use of manually adjustable timers and floats to prevent overflow. Rice, U.S. Pat. No. 6,460,622 & U.S. Pat. No. 6,615,924 introduced a programmable logic controller (PLC) with sensors for monitoring operational parameters which may change and then be used to re-calibrate timing. The present invention likewise uses a standard PLC served by information from the well.
 Prior art bailer pump systems provide for exhausting natural gas and recovering it at the wellhead (Rice, U.S. Pat. No. 6,460,622) and using conventional separating means (Rice, U.S. Pat. No. 6,615,924).
 Finally, bailer recovery systems provide inherent well stimulation each time the bailer plunges into a reservoir. The present invention utilizes additional novel stimulation means in wells where such means enhance production. For example, in reservoirs containing viscous fluids, or a suspension which effectively increases its viscosity, agitating the fluid enhances diffusion and may thereby improve production.
 Thus, the present invention provides an inexpensive means for recovering natural gas without interrupting production, a novel valve for unloading bailers and other vessels, and a novel means for treating downhole fluids to increase production, all with substantially reduced costs, risks of spillage and environmental damage.
SUMMARY OF THE INVENTION
 As with all prior art bailer pumps, the present invention utilizes a bailer pumping apparatus comprising a collection housing connected to a wellhead, a reversible motor driving a winch which reels in and unreels a cable carried over a pulley connected to a bailer. Bailers have means for loading and unloading fluids and a canister for holding them.
 Modern bailing pumps are controlled by a PLC. Typically, when the bailer is "home" in the collection housing, the winch is filled with cable, and the loaded canister unloads liquid. When the canister is empty, the PLC actuates the motor, and cable unwinds from the winch. When the bailer is immersed in the subterranean reservoir, the PLC stops the motor, and fluid flows into the canister. When the canister is full, the PLC reverses the motor direction and raises the bailer back up into the collection housing. When the bailer is back "home" in the collection housing, a sensor signals the PLC to stop the motor, and the steps described above are repeated as needed for production.
 There are a number of ways that PLC's may be programmed to time these events. For example, the load and unload times may be programmed manually or from feedback based on bailer weight, which may be monitored by a scale placed under the pulley. The decent and ascent times may be calculated by the PCL from the winch velocity and the depth of the reservoir, which may also be determined from feedback from the bailer based on its weight.
 The collection housing in a preferred embodiment of the present invention is a vertical stand pipe attached to the top of a well (wellhead). The housing is of sufficient length and inside diameter (ID) to contain a cylindrical bailer. The housing has an opening for the cable at the top with a wiper seal and cleaning means, and a sealing flange or surface for sealing the housing closed before liquids are unloaded into it from the bailer. A natural gas outlet and an outlet for produced liquids are connected to gas and liquid storage facilities. The simplicity of the collection housing greatly reduces its fabrication cost compared to existing bailer collection means.
 The bailer is normally a streamlined cylinder designed to slide smoothly into subterranean reservoir fluids. The outside diameter (OD) of the bailer and the ID of the well casing should be such that there is sufficient space for natural gas to vent around the bailer as it is lowered and raised through the casing, and the bailer may vary in length to accommodate the desired production rate as long as it does not exceed the length of its collection housing. The top of the bailer has a means for attaching the cable, orifices for filling the canister from the top and/or to allow it to vent air or other gases while filling from the bottom, and a means for accommodating fishing tools should the cable break. A check valve for filling the canister while the bailer is submerged in the reservoir may be in the bottom of the bailer or attached under it. The bailer used in the present invention also has a means for attaching a stimulator for use in wells where stimulation improves production and a novel double valve for (a) closing the housing used to collect liquid, and (b) for unloading liquid from a vessel inside said collection housing (BIVALVE) that includes a seal plate with at least two sealing surfaces, a retainer spring assembly and spring holder. The seal plate, which may be flat, oval, or ball-shaped as needed, has a first surface that is slightly larger than the ID of the collection housing, and a second surface that, when sealed to the canister or other vessel, prevents liquid contained therein from flowing out. This assembly provides a novel valve for unloading liquids from vessels.
 In some embodiments of the present invention, the check valve may be set to vent natural gas from the well through the canister, seal plate and check valve.
 The stimulation means in the present invention provides a novel means for increasing production from wells that benefit from its agitating action. The means, which acts as a plunger when immersed into and withdrawn from a fluid, is designed to create turbulence as it is lowered into and retrieved from a subterranean reservoir. Flat or cup-shaped stimulators create a pronounced wave as well as turbulence. The wave can move solid particles that have migrated through the formation into the bailer. Such wave motion is also expected to cause lower molecular weight hydrocarbons to be released as natural gas. Such gases stimulate diffusion when they bubble through a viscous fluid. Ball and flat disks also create turbulence. This turbulence and enhanced diffusion can help stir up and suspend solid particles in the wellbore so that they can be removed in the bailer.
 The stimulators used in the present invention come in numerous forms and configurations. The means employed is what works best for a specific well. Some wells might not benefit from stimulation. Production from other wells may be stimulated by means consisting of a plurality of circular plates and/or balls on a rod suspended from the bottom of the bailer. The plates may be flat and/or oval disks, and/or cup- and/or ball-shaped disks may be used. The rod length, number of disks and/or balls and their spacing will vary depending on reservoir fluid levels, fluid viscosity, debris buildup, and a number of other well characteristics.
 In the preferred embodiment of the present invention employed for wells benefiting from stimulation, when a bailer/stimulator assembly is lowered into and raised from a reservoir, the well fluid experiences pulse and agitation effects from the plunging action of the stimulators. This pulse or agitation promotes movement in the formation fluid near the wellbore (stimulation). When the bailer is immersed, its canister fills with reservoir fluid through the inlet check valve and/or through orifices in the top of the bailer. When the cable begins to lift the full bailer from the reservoir, the check valve closes. As the full canister is raised from the reservoir by the winch, the stimulators again creates pulses and agitation effects in the well fluid.
 The full bailer is pulled inside when it reaches the collection housing, and the invention's novel BIVALVE seals the collection housing closed and empties the canister. When the canister is empty, the winch reverses direction and lowers the bailer for another collection cycle.
 The sequence described above repeats itself as needed, limited solely by bailer travel and fill/drain times, which may be controlled and/or modified by the PLC as described previously.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 . . . General representation of the bailer recovery system (BRS).
 FIG. 2a . . . Embodiment of the Well Stimulation Means (WSM) using flat disks.
 FIG. 2b . . . Embodiment of the WSM using round disks.
 FIG. 2c . . . Embodiment of the WSM using cupped-shaped disks.
 FIG. 2d . . . Embodiment of the WSM using a combination of stimulator shapes.
 FIG. 3a . . . Embodiment of bailer with check valve above seal plate.
 FIG. 3b . . . Embodiment of bailer with check valve under seal plate.
 FIG. 3c . . . Illustration of ball check valve.
 FIG. 4a . . . The empty fluid collection housing (CCH).
 FIG. 4b . . . Illustration of bailer moving into or from CCH.
 FIG. 5a . . . "Closed" BIVALVE using a flat seal plate.
 FIG. 5b . . . "Open" BIVALVE using a flat seal plate.
 FIG. 6a . . . "Closed BIVALVE using a hemispheric seal plate.
 FIG. 6b . . . "Open BIVALVE using a hemispheric seal plate.
 FIG. 7a . . . "Closed" BIVALVE in a bailer recovery system (BRS).
 FIG. 7b . . . "Open" BIVALVE in a BRS.
 FIG. 8 . . . Another Preferred embodiment of the BIVALVE.
 FIG. 9a . . . BIVALVE in "transition state."
 FIG. 9b . . . "Closed" BIVALVE unloading liquid from canister.
 FIG. 10a . . . Illustration of bailer when it is nearly home.
 FIG. 10b . . . Bailer at "home" unloading liquid.
DETAILED DESCRIPTION OF THE INVENTION
 The invention disclosed herein is a bailer fluid production system and process. The invention utilizes a novel means for stimulating liquid hydrocarbon production, and a novel double valve for unloading it to storage facilities without exposing the environment to hydrocarbons during their uninterrupted production.
 FIG. 1 illustrates the invention generally as bailer recovery system (BRS) 10, which includes vertical, cylindrical collection housing (CCH) 12, and bailer 14. Sensor 16 signals the system's PLC (not shown) that bailer 14 is "home" inside housing 12. Cable 18 connects winch 20 to bailer 14 via pulley 22 through the top of housing 12 to connection means 24. Check valve 26 is used to load reservoir fluids into bailer 14 when bailer 14 is immersed in such fluids, the invention's novel BIVALVE 28 is used to close a collection housing (e.g. CCH 12) and unload liquid from a vessel therein (e.g. bailer 14), and weighing means 30, which may be a scale or a load cell, may be employed to monitor the weight of bailer 14. The entire system is installed atop wellhead 32, and the invention's novel well stimulating means (WSM) 34 may be attached under valve 26 and wellhead connection 36.
 FIG. 2 illustrates the invention's novel well stimulation means. WSM 34 comprises a plurality of stimulators 38 on rod 40, which may be removably attached externally to bailer 14 under it. WSM 34 is designed to create turbulence in standing fluids in well reservoirs. Depending on the type of stimulation needed for enhanced production, stimulators 38 may be flat and/or oval disks, and/or ball-shaped means (FIGS. 2a and 2b) may be used. The length of rod 40 and the number of stimulators 38 and their spacing will vary depending on reservoir fluid levels, fluid viscosity and a number of other well parameters. Stimulators 38 create turbulence which agitates and suspends solid particles in the wellbore, thereby facilitating their removal. Flat or cupped-shaped disks (FIG. 2c) also generate a pronounced wave. Such wave motion likewise stirs up solid particles that migrated through the formation and causes them to move into the wellbore where they can be removed. Such wave motion also causes "light ends" of hydrocarbons in the reservoir to be released as natural gas, which promotes flow of heavier hydrocarbons to the wellbore. In many applications, a combination of stimulator shapes FIG. 2d) may be preferred to enhance production.
 FIG. 3 illustrates how bailer 14 may vent natural gas and load reservoir fluid when it is downhole. Canister 42 is the portion of bailer 14 that holds reservoir liquids as bailer 14 is lifted from a subterranean reservoir. Before bailer 14 is immersed in reservoir fluid, check valve 26, which may be above seal plate 44 (FIG. 3a) or under it (FIG. 3b), may be open or closed, depending on environmental factors in the wellbore. For example, when the pressure of natural gas is sufficiently high, valve 26 is open, thereby permitting gas to vent through valve 26 and an opening in seal plate 44, thence through canister 42 and orifices 46.
 When winch 20 in FIG. 1 has unwound sufficient cable that empty canister 42 is immersed in a subterranean reservoir, stimulating means 34 creates pulse and agitation effects which promote movement in the formation fluid in the reservoir. When the fluid pressure exceeds the pressure required to open valve 26, valve 26 opens, thereby allowing fluid to flow into canister 42. Liquid may also load into canister 42 through orifices 46. When canister 42 is full, winch 20 in FIG. 1 begins to lift bailer 14 from the reservoir, and valve 26 closes. Scale 30 in FIG. 1 measures the weight of bailer 14 as it leaves the reservoir and the length of cable extending therein, thereby permitting a determination of the reservoir fluid level downhole.
 FIG. 3a illustrates an embodiment of the invention wherein check valve 26 is housed inside bailer 14 (above plate 44); FIG. 3b illustrates an embodiment wherein valve 26 is under bailer 14 (below plate 44). FIG. 3c illustrates the details of check valve 26 when a ball check valve is used. However, depending on the fluid characteristics of the well where it is used, valve 26 may be a ball, flapper or plunger check valve.
 FIG. 4 illustrates the collection housing in FIG. 1 when it is empty (FIG. 4a), and when bailer 14 is moving into or from housing 12 (FIG. 4b). CCH 12 includes sensor 16 for determining when bailer 14 is "home," wellhead connection 36 for connecting housing 12 to a wellhead, attachment means 48 for attaching a cable cleaning means for cleaning cable 18 before it passes through opening 50 and for closing opening 50, gas outlet means 52 for transferring natural gas to a gas storage facility (not shown), at least one fluid outlet means 54 for transferring produced fluids to a fluid storage facility (not shown), and sealing surface 56 for sealing seal plate 44. Basically, the ID and length of housing 12 is sufficient to house the bailer, except for plate 44 (described below) and stimulation means 34 (if attached). In FIG. 4b, bailer 14 is being lowered from or raised into housing 12 by cable 20.
 The present invention produces natural gas without interrupting production by venting gas through valve 26 and plate 44, canister 42 and orifices 46 and/or around the bailer to outlet means 52 and thence to a gas storage facility or pipeline (not shown). This function of the invention also prevents pressure from building up to dangerous levels, and/or being released into the atmosphere.
 FIGS. 5 and 6 illustrate preferred embodiments of the invention's novel BIVALVE being used to unload fluid from a cylindrical vessel (e.g. canister 42). BIVALVE 28 includes, spring 60, rod, 62, retaining plate 64, valve holder 66, top surface 68 of valve holder 66 and seal plate 44, which is the bottom of holder 66. When BIVALVE 28 is closed, plate 44 seals to the bottom of holder 66, thereby closing vessel 42. As vessel 42 moves toward its "home" position in housing 12, plate 44 engages sealing surface 56, thereby sealing housing 12 closed and preventing upward movement of retaining plate 64. "Overpull" of vessel 42 compresses spring 60 against retaining plate 64, thereby unsealing plate 44 and opening the bottom of vessel 42. Additional overpull of vessel 42 is limited by compression of spring 60 against retaining plate 64. After vessel 42 empties and begins to move back down, the compression of spring 60 is released, plate 44 is unsealed from sealing surface 56 and seals holder 66 closed.
 In the embodiment in FIG. 5, flat-type seal plate 44 seals to sealing surface 56 under the base of housing 12. In FIG. 5a, vessel 42 is entering housing 12, and plate 44 is sealed to vessel 42 and below sealing surface 56 (BIVALVE 28 is "closed"). In FIG. 5b, plate 44 seals to surface 56 as it begins to separate from the bottom of vessel 42 (BIVALVE 28 is in its "transition state"). In FIG. 5c, plate 44 is unsealed from holder 66, thereby permitting vessel 42 to unload liquid, but plate 44 seals the bottom of housing 12 closed, thereby preventing said liquid from escaping (BIVALVE 28 is "open").
 In the embodiment in FIG. 6, hemispherical type seal plate 44 plugs into sealing surface 56, which is the tapered rim of a circular opening in the base of housing 12. The narrowest diameter of said opening must be greater than the OD of vessel 42 but less than the diameter of seal plate 44. In FIG. 6a, plate 44 is unsealed from the bottom of holder 66, thereby permitting vessel 42 to unload liquid, but plate 44 seals the bottom of housing 12 closed, thereby preventing said liquid from escaping (BIVALVE 28 is "open"). In FIG. 6b, plate 44 seals the bottom of vessel 42 closed, and the bottom of housing 12 is no longer sealed shut, thereby permitting vessel 42 to exit housing 12 (BIVALVE 28 is "closed").
 FIG. 7 illustrates the use of BIVALVE 28 in a bailer recovery system. In FIG. 7a, bailer 14 is full of oil and has entered housing 12, but seal plate 44 has not yet reached sealing surface 56 and is still sealed to the bottom of holder 66 (BIVALVE 28 is "closed"). In FIG. 7b, sensor 16 signals the system's PLC (not shown) that bailer 14 is "home," and BIVALVE 28 is unloading fluid from canister 42 into housing 12 (BIVALVE 28 is "open"). Said fluid is transferred to storage facilities (not shown) through fluid outlet 54 in housing 12.
 FIG. 8 illustrates a different embodiment of BIVALVE 28. In FIG. 8, BIVALVE 28, which includes spring 60, rod, 62, retaining plate 64, valve holder 66, top surface 68 of valve holder 66 and seal plate 44 is in its "transition state" where seal plate 44 has reached sealing surface 56, but is still sealed to the bottom of holder 66 (BIVALVE 28 is "in transition").
 FIG. 9 illustrates how BIVALVE 28 moves from its transition state (FIG. 9a) to its open position (FIG. 9b). In FIG. 9, BIVALVE 28, which includes spring 60, rod, 62, retaining plate 64, valve holder 66, top surface 68 of valve holder 66 and seal plate 44, is housed in the bottom of bailer 14. In FIG. 9a, bailer 14 is inside collection housing 12, seal plate 44 has reached sealing surface 56 of collection housing 12, but plate 44 is still sealed to bottom 70 of bailer canister 42 under holder 66 (BIVALVE 28 is in "transition"). In FIG. 9b, spring 60 is compressed against retaining plate 64 as wench 20 in FIG. 1 overpulls bailer canister 42 approximately two and a half inches into housing 12. The compression of spring 60 seals plate 44 to sealing surface 56, thereby sealing collection housing 12 closed, as the overpull of bailer 14 separates bottom 70 of canister 42 from plate 44, thereby permitting gravity to unload liquid from bailer 14 into housing 12.
 FIG. 10 illustrates bailer 14 moving into its "home" position in collection housing 12. In the embodiment in FIG. 10, BIVALVE 28 is the version of the bivalve shown in FIG. 9. In FIG. 10a, bailer 14 is nearly "home" as in FIG. 9a. In FIG. 10b, the top of bailer 14, which is overpulled approximately two and a half inches into housing 12, is detected by sensor 16. Sensor 16 signals the system's PLC (not shown) that bailer 14 is "home." As shown in FIG. 9b, plate 44 has separated from the bottom of canister 42, thereby unloading liquid from bailer canister 42 into collection housing 12.
Patent applications in class Producing the well
Patent applications in all subclasses Producing the well