Abstract:
A hydraulically powered downhole jet pump is designed to provide greater flexibility in operations of wells producing oil, gas and/or water. The pump consists of a housing and a carrier assembly. The housing is attached to an inner threaded tubular member and run inside the well casing to a depth as required for optimal operations. The one piece carrier assembly is inserted and seals into the housing with proper orientation of the carrier assembly outlet ports with the housing outlet ports resulting from the combination of a helically or tapered cut guide on the exterior of the carrier assembly and an inward positioned pin in the housing.

Description:
[0001]    This application is continuation of U.S. application Ser. No. 13/357,730 filed on Jan. 25, 2012. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a hydraulically powered jet pump for placement downhole in a well for the purpose of producing fluids (oil, gas, and/or water) from a formation which has special features that provide flexibility and ease of operations in various types of well applications. The operation of a jet pump is well known in the art and as such utilizes high pressure fluid pumped from the surface to a small interior diameter nozzle where the flow is converted to high velocity and lower pressure. As the fluid flow departs the nozzle, pressure at the exit point is greatly reduced thus drawing in fluids from an exterior source such as an oil and gas producing formation. The mixture is then flowed through a mixing tube which has a sequentially increasing interior diameter thus reducing velocity and increasing pressure. As the fluid mixture departs the pump into the well annulus, a sufficient pressure is available to cause the fluid mixture to return to the surface. 
         [0004]    2. Description of Related Art 
         [0005]    The patent to Coleman U.S. Pat. No. 5,372,190 discloses a jet pump that includes a jet orifice and diffuser portion not numbered in FIG. 9 and a second diffuser member 148 that is attached to a tubular member 164 that includes an alignment edge 166 that cooperates with pin 170. In order to remove the assembly, the jet orifice and diffuser portion must first be removed and then the second member 148 is retrieved using a tool that is lowered by a wire line or coiled tubing and that engages profile 204. The patent to Batho et al U.S. Pat. No. 7,114,572 discloses a jet pump 50 and a subsurface safety valve 52. The patent to Kelly et al U.S. Pat. No. 7,219,737 discloses generally a jet pump 44 that can be moved upwardly in tubing into a retrievable position by fluid injected into the casing of a well. Finally, Jackson U.S. Pat. No. 7,909,089 discloses a jet pump 110 that can be configured to pump well fluid up through a tubing string. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of an embodiment of the invention, a jet pump includes a housing and a carrier. The housing interior is of a constant diameter so that the carrier can easily be inverted and thus provide a means to use the pump as described above but with high pressure power fluid being conveyed down the annulus between the outer diameter of the inner tubular member and the well casing interior with the power fluid and formation production returning to the surface through the interior of the inner tubular. This flow method is preferred in wells where the produced fluid is corrosive and therefore not desirable to contact the well casing interior or in wells where a failsafe safety shut-in valve is desired or required. This configuration is typically called a “reverse flow” pump and requires wireline operations to run and retrieve. 
         [0007]    The novel design of the reverse flow pump and latching device allows for placement of the pump into the well by simply dropping or pumping the assembly down to seat in the proper position and to latch into position to prevent the pump from being displaced upward when power fluid pressure is applied to the annulus. The novel design of the latching device is critical to the assembly and is activated to the locked position by means of pressure applied to the interior tubing and thus temporarily plugged assembly. In addition to placement and locking of the pump into the proper position, a novel mechanism is also provided that allows for retrieval of the pump without the use of a wireline conveyed pulling tool thus greatly reducing the operating cost normally associated with retrieval of a reverse flow pump. 
         [0008]    The retrieval mechanism consists of a pulling tool with a seal cup positioned above. The mechanism is then pumped down the interior tube until it encounters and latches onto the fishing neck of the pump lock. Pressure is then applied to the annulus and causes an upward force via the seal cups to move the release sleeve upward and release the latching dogs and thus allowing the pump and latch assembly to be forced back to the surface thru continued circulation where the assembly can be captured at the surface and removed for design changes or repairs. 
         [0009]    By developing a carrier which contains the nozzle and mixing tube in a single component, the housing can then be of simple design with enlarged interior diameter versus exterior diameter as compared to other tools on the market. The larger exterior diameter of the carrier therefore allows the use of larger nozzle and mixing tube diameters and thus increased production rates from a formation. For example, existing tools of a 3″ to 3.5″ outside diameter are limited to production rates in the maximum range of 100 gallons per minute whereas this novel design can easily achieve rates in excess of 200 gallons per minute. 
         [0010]    Another objection for using existing jet pumps is the inability or difficult operations required to obtain access to the producing formation for purposes of evaluation of formation data or modification of the well completion. This novel design allows easy removal of the carrier, standing valve and safety valve from the interior of the inner tubing thus allowing full access through the remaining pump housing and to the wellbore below. Pending well conditions, the carrier, standing valve and safety valve can be removed from the well by reversing the power fluid circulation direction and capturing the tools as they reach the surface. In wells where the formation pressure is low and thereby will not allow reverse circulation, the tools (carrier, standing valve and safety valve) can be removed using a wire and special retrieving tool to provide full access to the wellbore below the pump housing assembly. 
         [0011]    In wells located in hostile or sensitive environments such as the Arctic areas, wildlife refuges and offshore, rules and regulations often require that each well be equipped with a failsafe downhole valve to prevent the flow of oil and gas to the surface in case of a failure of the surface valving or integrity of the well. This tool configuration can include such a device when required or desired and operates by being open only when power fluid pressure is applied and automatically closes anytime power fluid pressure is reduced. Another advantage of the safety device is that there are no depth limits at which the valve can be placed as is the case in safety valves that are operated by a special tubular line run from the surface to the valve and the valve operated by applying pressure to the line and thus to the valve. 
         [0012]    Another feature of this novel design overcomes the typical problem associated with damaging or washing seals such as “O” Rings out of their grooves. In standard seal design, there is a requirement to provide some amount of “squeeze” as a seal enters into a bore such that the interference creates the initial seal between the part containing the seal and the receiving device bore. Most seals are activated to an improved “squeeze” when pressure is applied. When passing in and out of seal bores, each entry and exit of a seal from the bore has potential to damage the seal and eliminate or drastically reduce the interference and the efficiency of the initial seal. The initial seal is critical in order for applied differential pressure to further activate the seal. In the novel design, standard type seal which require some interference fit (squeeze) are replaced with a seal made of a swellable elastomer that does not require an initial squeeze. Swellable elastomers can be provided that increase in size (swell) in the presence of fresh water, salt water, oil or gas. All of these fluids are typically contained in oil or gas wells. By utilizing a swellable elastomer as the seal, there is no need for the seal to be installed at a larger outside diameter than the outside metal diameter of the tool and therefore the seal is not exposed to damage that may result from contact with the well tubing or from flow washing while running the tool into the well. Once the tool is positioned into the bores, swelling of the elastomer automatically creates the squeeze and establishes the initial seal between the inner tool and bore and may be further activated for controlling high pressure thru the application of pressure after some amount of swelling has occurred. 
         [0013]    Another feature of the disclosed invention is to use shape memory materials, such as metals, for seal construction. Shape memory material can be manufactured in a specific shape at a base temperature and then formed into a different shape at a different temperature. It is therefore feasible to manufacture a shape memory material with a size that would create interference between the carrier and housing bore at a temperature such as 150 degree F., typical of even shallow oil and gas wells, but would not have interference at a lower temperature. Once the tool is placed into the housing bore without interference and the well temperature increases to above 150 degrees F., the material returns to the original manufactured shape which does provide interference and thus sealing capability. Using a corrosion resistant metal could greatly enhance the life of the seals in wells where corrosive fluids are produced. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0014]      FIG. 1  is a cross sectional view of the housing according to an embodiment of the invention. 
           [0015]      FIG. 1   a  is a view along line A-A of  FIG. 1 . 
           [0016]      FIG. 2  is a cross sectional view of the carrier assembly according to an embodiment of the invention. 
           [0017]      FIG. 2   a  is a partial frontal view of the carrier assembly. 
           [0018]      FIG. 3  is a cross sectional view of an embodiment of the jet pump assembly. 
           [0019]      FIG. 4  is cross sectional view of a second embodiment of the jet pump assembly. 
           [0020]      FIG. 4   a  is a cross sectional view of the locking mechanism in a locked position. 
           [0021]      FIG. 4   b  is a cross sectional view of a fishing tool engaging the upper portion of the jet pump assembly. 
           [0022]      FIG. 4   c  is a view of the upper portion of the jet pump assembly as pressure is applied from above to pump out the assembly. 
           [0023]      FIG. 5  is a schematic view of a typical well installation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 5  shows a typical well construction utilizing a hydraulic jet pump and associated completion equipment. A well normally has a casing string  11  extending from surface to or below the producing formation  12  and is cemented in place as shown at  13 . Slots or perforations  14  in the casing allow flow of production fluids from the formation into the inside of the casing  11 . An additional tubular member, called tubing  15 , extends from surface to a packer  16  which seals the annulus  17  between the tubing  15  and casing  11 . A jet pump housing  18  is run as an integral part of the tubing  15  and is positioned above the packer. The housing accepts the pump carrier  19  with nozzle and mixing tube components and thereby provides the means to artificially lift produced fluids from the lower part  20  of the well to the surface. 
         [0025]      FIG. 1  is a cross section of a housing  18  which is included by threaded means to the tubing  15  and positioned above the packer  16 . A top sub  21  connects the tubing to the housing by various types of threads common for use in oil and gas wells. The top sub is connected by threads to a sleeve  22  used for correct spacing of the various seal bores of the housing. The lower end of the sleeve is connected to the exit port sub  23 . The exist port sub is connected to a lower sub  24  which in turn is connected by threads to the well tubing  15 . 
         [0026]    Included in  FIG. 1  is a restricted or smaller inside diameter shoulder  29  for insertion and restriction of a standing valve (not shown). A guide pin  28  extends into the interior of the seal bore of the exit port sub for contact with a helical surface  40  of the lower end of the carrier and thus assuring proper orientation of the carrier when positioned inside the housing. 
         [0027]    As shown more fully in  FIG. 3 , an eccentric flow path  25  extends partially around the inside diameter of the exit port sub and provides a means for produced fluids to flow from the formation, thru the interior of the tubing and alongside the carrier to the inlet ports  33  of the carrier when the carrier is in its proper position inside the housing. A port  26  in the exit port sub  23  provides a communication means from the exit flow path  49  of the carrier, thru the exit port sub wall and into the annulus  19  of the well. 
         [0028]    As shown in the cross section of the carrier assembly  10  in  FIG. 2 , a fishing neck  31  is provided on the top of the carrier assembly for convenience of retrieval from the well using well known wireline conveyed fishing tools which are designed to latch onto the shoulder  37  and retrieve the carrier assembly from the well. A shoulder  31   a  at the lower end of the fishing neck is slightly larger than the outside diameter of the carrier body  32  and provides a stopping means to properly position the carrier assembly inside the housing as it cannot pass the shoulder  27  of  FIG. 1 . 
         [0029]    The body  32  of the carrier is connected by threads  36  to the fishing neck  31  on the upper end and the lower carrier sub  39  on the lower end. Internal to the body are the critical components of the pump, nozzle  34  and mixing tube  35  which are each positioned properly by an interference fit shoulder  34   a  and  35   a  respectively. A series of ports  33  in the wall of the body allow produced fluids to enter into the interior of the body at the outlet end of the nozzle where a low pressure area has been created as a result of the extremely high velocity exiting from the tip of the nozzle. Fluid pumped down the interior of the tubing and into the interior of the carrier  46  passes into the tapered flow path  45  of the nozzle where pressure is decreased and velocity increased as well known in the art. As the fluid exits the tip of the nozzle at high velocity, a responding reduction in pressure occurs thereby pulling produced fluids into the area immediately below the tip of the nozzle. The mixture of fluids enters the mixing tube and flows down a sequentially larger diameter flow path  44  in the mixing tube. With the increasing interior flow area, velocity is reduced and subsequently pressure increased. The flow continues downward inside the lower carrier body with increasing diameter and turns to exit from the carrier  45  and through the ports of the exit port sub  23  of the housing as shown in  FIG. 3  where a sufficient increase in pressure at the exit point can overcome the hydrostatic pressure of the fluids from the depth of the pump to the surface and thereby pump the mixture back to the surface for separation and further processing as may be required to allow sale of the oil and gas and reuse or disposal of the produced water. As shown in  FIG. 2   a  a tapered lower end of the lower carrier body  40  engages the guide pin  28  extending into the interior of the housing and automatically follows the taper and into the guide slot  41  to properly orient the carrier such that the exit ports of the lower carrier body and exit port sub are aligned. 
         [0030]    In addition to the interference seal achieved at the larger diameter of the fishing neck  31  a against the top sub restriction  27  an additional seal such as an “O” Ring  34   a  may be provided as a backup sealing mechanism. Additional seals  48   a  are required to seal above and below the exit port of the carrier and the exit ports of the exit port sub  23 . 
         [0031]    Under certain well conditions, a check valve  79  as shown in  FIG. 3 , often called a standing valve, is required to prevent produced and power fluids from flowing back into the formation when pumping has ceased. In this configuration, a fish neck  72  is provided to allow retrieval of the standing valve in such cases as access to the formation is desired. A shoulder  73  is provided on the standing valve to prevent the valve from passing through the housing seat  29  and provides a metal to metal seal between the standing valve and the housing. As certain well conditions could exist where formation pressure is lower than the hydrostatic pressure above the standing valve, an equalizing mechanism is provided such as a sealed piston  74  which is held in place by shear pins  75 . When retrieving the standing valve, it is necessary to add an equalizing prong to the fishing tool and mechanically contact the piston to forcefully expel the piston and allow the well pressures to equalize before attempting to retrieve the standing valve. 
         [0032]      FIGS. 4 ,  4   a ,  4   b , and  4   c  depict the sequential operation of an embodiment of the novel reverse flow pump. Once the carrier assembly is positioned against the restricted shoulder  31  a, a temporary device such as a dissolvable ball  51 , rupture disk or lightweight ball is provided to seal the interior diameter of a sliding sleeve  81  with Seal  81   a  which includes a fishing neck  31  and thereby provides a piston area to generate a force when pressure is applied to shear the retaining pin  53  and move the sleeve and fishing neck downward, forcing the larger diameter shoulder  54  under the dogs  56  whereby the dogs are moved into the groove  21   a  of the top sub  21  of the pump housing, as shown in  FIG. 4   a.    
         [0033]    In this series of depictions, the carrier body  36  containing the nozzle  34  and mixing tube  35  is inverted thereby providing a pumping means wherein the power fluid is pumped down the annulus between the tubing  15  and the casing  11  and produced fluid mixture returns to surface up the tubing. 
         [0034]      FIG. 4   a  shows the assembly locked in position after applying pressure above the pump and forcing the shoulder  54  under the dogs  56  and forcing the dogs outward and into the groove  21   a  of the top sub  21 . A variety of means can be added to the end area of the smaller outside diameter section  55  of the fishing neck  31  to provide some resistance to inadvertent upward movement of the fishing neck during operations of the pump. 
         [0035]      FIG. 4   b  depicts the initial step of retrieval of the pump carrier wherein a standard type fishing tool  62  which is modified to contain a seal cup  61  or other sealing mechanism to at least partially seal between the fishing tool and tubing interior wall. The fishing tool and seal cup are then dropped into the tubing and allowed to fall to the top of the pump or the assembly can be pumped into position. The end of the fishing tool contains dog latching aims and a shoulder  63  that is allowed to expand over the pump fishing neck  31  and latch underneath the fishing neck shoulder  37 . The fishing tool is also provided with a secondary fishing neck  62   a  in case operational problems require that conventional wireline operations are used to retrieve the fishing tool or pump. 
         [0036]      FIG. 4   c  depicts the released position of the pump wherein pressure is applied to the annulus in the same manner as when the pumping operations were active. The applied pressure acting against the seal cup creates an upward force that move the fishing neck  31  and the large diameter section  54  upward and out from under the dogs  55 , allowing the dogs to retract from the groove  21  a and releasing the locking mechanism to allow upward movement of the entire assembly. Continued circulation of fluids down the annulus and up the tubing causes the tool to be pumped to the surface where a variety of prior art and known methods allows the tool to be captured and removed from the well for repairs, redesign or other modifications. 
         [0037]    Seals  48   a  may be made from a swellable elastomer material or from a shape memory material. As discussed above, the seals may be initially sized so that the seals are not deformed as the carrier assembly is positioned within the housing. Rather, upon exposure to well fluids or elevated temperatures, the seal increases in size to form a seal between the housing and the carrier assembly. 
         [0038]    Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.