Abstract:
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.

Description:
FIELD OF INVENTION 
       [0001]    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 
       [0002]    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. 
         [0003]    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. 
         [0004]    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. 
         [0005]    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. 
         [0006]    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 &amp; 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. 
         [0007]    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). 
         [0008]    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. 
         [0009]    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 
       [0010]    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. 
         [0011]    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. 
         [0012]    There are a number of ways that PLC&#39;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. 
         [0013]    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. 
         [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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. 
         [0019]    The full bailer is pulled inside when it reaches the collection housing, and the invention&#39;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. 
         [0020]    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 
         [0021]      FIG. 1  . . . General representation of the bailer recovery system (BRS). 
           [0022]      FIG. 2   a  . . . Embodiment of the Well Stimulation Means (WSM) using flat disks. 
           [0023]      FIG. 2   b  . . . Embodiment of the WSM using round disks. 
           [0024]      FIG. 2   c  . . . Embodiment of the WSM using cupped-shaped disks. 
           [0025]      FIG. 2   d  . . . Embodiment of the WSM using a combination of stimulator shapes. 
           [0026]      FIG. 3   a  . . . Embodiment of bailer with check valve above seal plate. 
           [0027]      FIG. 3   b  . . . Embodiment of bailer with check valve under seal plate. 
           [0028]      FIG. 3   c  . . . Illustration of ball check valve. 
           [0029]      FIG. 4   a  . . . The empty fluid collection housing (CCH). 
           [0030]      FIG. 4   b  . . . Illustration of bailer moving into or from CCH. 
           [0031]      FIG. 5   a  . . . “Closed” BIVALVE using a flat seal plate. 
           [0032]      FIG. 5   b  . . . “Open” BIVALVE using a flat seal plate. 
           [0033]      FIG. 6   a  . . . “Closed BIVALVE using a hemispheric seal plate. 
           [0034]      FIG. 6   b  . . . “Open BIVALVE using a hemispheric seal plate. 
           [0035]      FIG. 7   a  . . . “Closed” BIVALVE in a bailer recovery system (BRS). 
           [0036]      FIG. 7   b  . . . “Open” BIVALVE in a BRS. 
           [0037]      FIG. 8  . . . Another Preferred embodiment of the BIVALVE. 
           [0038]      FIG. 9   a  . . . BIVALVE in “transition state.” 
           [0039]      FIG. 9   b  . . . “Closed” BIVALVE unloading liquid from canister. 
           [0040]      FIG. 10   a  . . . Illustration of bailer when it is nearly home. 
           [0041]      FIG. 10   b  . . . Bailer at “home” unloading liquid. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]    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. 
         [0043]      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&#39;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&#39;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&#39;s novel well stimulating means (WSM)  34  may be attached under valve  26  and wellhead connection  36 . 
         [0044]      FIG. 2  illustrates the invention&#39;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. 2   a  and  2   b ) 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. 2   c ) 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. 2   d ) may be preferred to enhance production. 
         [0045]      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. 3   a ) or under it ( FIG. 3   b ), 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 . 
         [0046]    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. 
         [0047]      FIG. 3   a  illustrates an embodiment of the invention wherein check valve  26  is housed inside bailer  14  (above plate  44 );  FIG. 3   b  illustrates an embodiment wherein valve  26  is under bailer  14  (below plate  44 ).  FIG. 3   c  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. 
         [0048]      FIG. 4  illustrates the collection housing in  FIG. 1  when it is empty ( FIG. 4   a ), and when bailer  14  is moving into or from housing  12  ( FIG. 4   b ). 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. 4   b , bailer  14  is being lowered from or raised into housing  12  by cable  20 . 
         [0049]    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. 
         [0050]      FIGS. 5 and 6  illustrate preferred embodiments of the invention&#39;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. 
         [0051]    In the embodiment in  FIG. 5 , flat-type seal plate  44  seals to sealing surface  56  under the base of housing  12 . In  FIG. 5   a , 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. 5   b , 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. 5   c , 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”). 
         [0052]    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. 6   a , 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. 6   b , 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”). 
         [0053]      FIG. 7  illustrates the use of BIVALVE  28  in a bailer recovery system. In  FIG. 7   a , 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. 7   b , sensor  16  signals the system&#39;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 . 
         [0054]      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”). 
         [0055]      FIG. 9  illustrates how BIVALVE  28  moves from its transition state ( FIG. 9   a ) to its open position ( FIG. 9   b ). 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. 9   a , 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. 9   b , 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 . 
         [0056]      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. 10   a , bailer  14  is nearly “home” as in  FIG. 9   a . In  FIG. 10   b , 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&#39;s PLC (not shown) that bailer  14  is “home.” As shown in  FIG. 9   b , plate  44  has separated from the bottom of canister  42 , thereby unloading liquid from bailer canister  42  into collection housing  12 .