Abstract:
A subsea well pumping system for installing and retrieving a hydraulically actuated down hole pump employed within the tubing suspended within casing extending from above a seabed, the system having a wellhead assembly affixed to the upper end of the casing for supporting the tubing and including provision for hydraulically communicating with the interior of the casing and the tubing, a remotely controllable main valve affixed to the tubing at its upper end, a tubular pump lubricator affixed at its lower end to the main valve, a removable pump latch sealably closing the pump lubricator at its upper end and having a pump catcher extending downwardly therefrom for removably latching onto the pump and a system for guiding the pump suspended form the pump catcher into the pump lubricator whereby the pump can be moved downwardly in the tubing into a pumping position by fluid injected into the tubing and can be moved upwardly in the tubing into a retrievable position for grasping by the pump catcher by fluid injected into the casing.

Description:
BACKGROUND OF THE INVENTION 
     The invention disclosed herein is concerned with underwater pump installations and more particularly with systems, methods and apparatus for installing a hydraulically actuated down hole pump employed in tubing suspended within casing extending from above a sea bed but below the surface of an ocean or other body of water. 
     The increasing demand for oil and gas has greatly stimulated the drilling and operation of subsea wells. Substantial prior art has been developed with respect to subsea wells and with respect to installing and retrieving hydraulically actuated down hole pumps. For examples of such prior art reference may be had to the following: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Patent Number 
                 Inventor 
                 Issue Date 
               
               
                   
               
             
             
               
                 3,115,933 
                 Haeber 
                 Dec. 31, 1963 
               
               
                 3,168,143 
                 Watkins 
                 Feb. 2, 1965 
               
               
                 3,282,336 
                 Wakefield 
                 Nov. 1, 1966 
               
               
                 3,452,815 
                 Watkins 
                 Jul. 1, 1969 
               
               
                 4,003,428 
                 Zehren 
                 Jan. 18, 1977 
               
               
                 4,331,203 
                 Kiefer 
                 May 25, 1982 
               
               
                 4,391,330 
                 Kiefer 
                 Jul. 5, 1983 
               
               
                 4,400,112 
                 Castel, et al. 
                 Aug. 23, 1983 
               
               
                 4,405,263 
                 Hall 
                 Sep. 20, 1983 
               
               
                 4,667,986 
                 Johnson, et al. 
                 May 26, 1987 
               
               
                 4,673,041 
                 Turner, et al. 
                 Jun. 16, 1987 
               
               
                 4,825,953 
                 Wong, et al. 
                 May 2, 1989 
               
               
                 4,993,492 
                 Cressey, et al. 
                 Feb. 19, 1991 
               
               
                 5,088,558 
                 Mohn 
                 Feb. 18, 1992 
               
               
                 6,609,571 
                 Nice, et al. 
                 Aug. 26, 2003 
               
               
                   
               
             
          
         
       
     
     In general, the techniques revealed in these previously issued patents suffer from one or more of the following deficiencies: complexity, high cost, reliability, inefficiency, exposure of the pipe assembly to damages, insecure and inadequate mounting and sealing of pump assemblies in the wellhead, exposure of installation apparatus and systems to seawater and failure to adequately protect the environment. The invention disclosed herein overcomes many of these deficiencies. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention herein provides a subsea well pumping system for installing and retrieving a hydraullically actuated down hole pump. The system includes the use of tubing suspended within casing in a well bore hole, the casing extending from above a seabed. 
     The system includes a wellhead assembly affixed to the upper end of the casing for supporting the tubing. Further, the wellhead assembly include the provision for hydraulically communicating with the interior of the casing and the tubing. 
     A remotely controllable main valve is affixed to the tubing at its upper end. A tubular pump lubricator is affixed to the main valve. A removable pump latch sealably closes the pump lubricator at its upper end and has a pump catcher extending downwardly from it. The function of the pump catcher is for removably latching onto a hydraulically actuated down hole pump. 
     As one example of the application of the invention a system is provided for guiding the hydraulically actuated down hole pump suspended from the pump catcher into a pump lubricator. From the pump lubricator, the down hole pump can be moved into the tubing and thereby into a pumping position by fluid injected into the tubing. The pump can be moved upwardly in the tubing into a retrievable position for grasping by the pump catcher by fluid injected into the casing. That is, the hydraulically actuated down hole pump may be moved into a lower position within the bottom of the tubing or to an upper position for retrieval both by means of hydraulic fluid pressure. 
     The subsea well pumping system of this invention includes, in one embodiment, a wire line guide assembly including at least one wire line secured at its lower end in fixed relationship to the well head and a wire line installation and retrieval assembly for guiding the hydraulically actuated pump into the pump lubricator. In another application of the invention, the use of guide wires are not required and instead divers and remote operated vehicles (ROV&#39;s) can be employed to install and retrieve the pump. 
     A better and more complete understanding of the invention will be obtained from the following detailed description of the preferred embodiment taken in conjunction with the attached claims and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  provides is an elevational diagrammatic view of a subsea well having casing suspended therein and, received within the casing tubing, that extends from a subsea surface down to a producing formation. A hydraulically actuated down hole pump shown in dotted outline as the pump is being positioned within a pump lubricator. 
         FIG. 2  is an elevational diagrammatic view as  FIG. 1  showing the hydraulically actuated down hole pump fully received within the pump lubricator and a pump latch in sealed position closing the top of the lubricator. 
         FIG. 3  is an elevational view as in  FIGS. 1 and 2  showing the hydraulically actuated down hole pump having passed through a main valve and into the tubing as the pump is being moved downwardly into an operating position by fluid flow. 
         FIG. 4  shows the hydraulically actuated down hole pump in operating position as received by a standing valve. In this Figure, crude oil is being pumped from a producing formation. 
         FIG. 5  shows the hydraulically actuated down hole pump in the process of being retrieved from its operating position at the bottom of the tubing. The pump is shown as it is being moved in an upward direction within the tubing, by hydraulic action of fluid flow. 
         FIG. 6  shows the hydraulically actuated down hole pump having moved through the main valve and received within the pump lubricator. 
         FIG. 7  shows the hydraulically actuated down hole pump as it is grasped by a pump latch that is affixed to the end of a wire line showing one system for retrieving the pump by which it can be moved to a location at the sea surface where it can be repaired or replaced. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It is understood that the invention disclosed herein is capable of being practiced using different systems and types of apparatus and that the description herein is to exemplify one embodiment. The invention is not limited to the illustrated embodiments disclosed herein but is to be limited only by the scope of the claim or claims including the full range of equivalency to which each element or step thereof is entitled. 
     In illustrating and describing the invention, numerals are used to indicate elements as follows:
       10  sea floor     12  sea surface     14  bore hole     16  casing     18  upper end     20  perforations     22  tubing string     24  safety valve     26  packer     28  annular fluid channel     30  connecting pipe     32  upper end     34  main valve     36  pump lubricator     38  pump latch     40  upper end     42  pump catcher     44  down hole pump     46  production flow line     48  power fluid flow line     50 A– 50 G flow control valves     52  guideline wire     54  guide wire     56  anchor     58  tubular guide     60  extension     62  attachment member     64  ports     66  bottom hole assembly     68  standing valve   

     The figures herein are diagrammatic views of a subsea well pumping system shown in a subsea environment, the sea floor being indicated by the numeral  10  and the surface of the sea by the numeral  12 . The pumping system may include the use of a floating platform (not shown) positioned on sea surface  12  or the system may be employed with a fixed platform (not shown) having legs that extend down to rest upon the sea floor  10 . 
     The well shown in the drawings is created by first drilling a bore hole  14  that extends from the sea floor  10  downwardly in the earth to a producing oil and/or gas formation. Positioned within bore hole  14  is a metal casing  16  that has an upper end  18  above the sea floor  10 . Adjacent a lower end of casing  18  perforations  20  are formed to permit crude oil to flow into the lower portion of the casing so that it can be pumped to the earth&#39;s surface. 
     Positioned within casing  16  is a tubing string  22  that extends down to adjacent the casing lower end to the area in communication with perforations  20 . Affixed to the lower end of tubing  20  is a subsurface safety valve  24 . Above valve  24  a packer  26  is positioned to sealably close off the upper interior portion of casing  16 . In this manner there is provided a closed annular fluid channel  28  within casing  16  above the packer and exterior to tubing  22 . A connecting pipe  30  communicates with the closed annular fluid channel  28 . 
     The upper end  32  of tubing string  22  communicates with a main valve  34 , shown diagrammatically. When fully opened, main valve  34  provides a passageway therethrough at least substantially equal to the interior diameter of tubing  22 . Affixed at an upper end of main valve  34  is a pump lubricator  36 . A pump latch  38  removably closes the upper end  40  (See  FIG. 1 ) of pump lubricator  36 . Secured to pump latch  38  is a pump catcher  42  that has facilities for removably latching onto a hydraulically actuated down hole pump  44 , shown in dotted outline. 
     Connected to the well as shown in  FIG. 1  is a production flow line  46  and a power fluid flow line  48 . Flow lines  46  and  48  extend to the earth&#39;s surface where they are connected to equipment (not shown) for receiving crude oil production from the well and for introduction of power fluid to the well. 
     In addition to main valve  48 , operation of the well utilizes seven flow control valves identified by the numerals  50 A– 50 G. Flow control valves  50 A,  50 D and  50 F are connected to power fluid flow line  48 . Valves  50 B,  50 C,  50 E and  50 G are connected to production flow line  46 . Each of flow control valves  50 A– 50 G are remotely controllable from the earth&#39;s surface. Control cables that extend from the earth&#39;s surface to valves  50 A– 50 G are not shown. 
     Down hole pump  44  can be placed into or removed from the interior of pump lubricator  36  in a variety of ways such as by a wire line, by guide wires, by a remote operated vehicle or by diver assistance. In the drawings, a method of removable and installation of pump  44  is shown by use of a guide line wire  52  and with the use of a guide wire  54 , as one example of a method of practicing the invention. In the illustrated arrangement, the guide wire  54  is affixed at its lower end to an anchor  56  that is secured to the upper end  18  of casing  16 . Slideably received on guide wire  54  is a tubular guide  58  having an extension  60  by which pump latch  38  is guided. As above stated, this procedure for guiding down hole pump  44  into and out of pump lubricator  36  is by way of example only as it can be done with the use of a remote operated vehicle or by a diver. 
       FIG. 1  shows the system as used for installing a down hole pump  44 . Pump  44  may be a new pump or it may be a pump as initially used in the well that has been removed and repaired. In the arrangement of  FIG. 1 , all the valves  34  and  50 A– 50 G are closed. Pump latch  38  is maneuvered so that pump  44  extending downward from pump catcher  42  is positioned to be received into the upper open end  40  of pump lubricator  36 . 
     After pump  44  is placed fully within lubricator  36  as shown in  FIG. 2  pump latch  38  is secured in position, and pump  44  is released from catcher  42 . 
     Thereafter, main valve  34  is opened permitting pump  44  to pass downwardly therethrough and into tubing  22  as seen in  FIG. 3 . Pump  44  is circulated downwardly within tubing  22  by hydraulic force of power fluid from flow line  48  flowing through opened flow control valve  50 A. That moves power fluid into lubricator  36  and downwardly through tubing  22 . This downward flow of power fluid through tubing  22  passes into annular fluid channel  28  through ports  64  in a bottom hole assembly  66 . The power fluid passing upwardly in annular fluid channel  28  and into production flow line  46  through open flow control valve  50 G. 
     Flow in the manner illustrated in  FIG. 3  continues until pump  44  is seated in bottom hole assembly  66  as shown in  FIG. 4 . Bottom hole assembly  66  includes a standing valve  68 . The function of standing valve  68  is, after pump  64  has been seated therein, to block downward fluid flow within tubing  22  but to permit flow into the bottom end of the tubing through safety valve  24 . 
       FIG. 4  shows down hole pump  44  in a seated position and ready for use to pump fluid from within casing  16  below packer  26  to the earth&#39;s surface. This is accomplished as illustrated in  FIG. 4  by pumping power fluid downwardly through power fluid flow line  48 , through open flow control valve  50 D and into the upper end of tubing  22 . The power fluid actuates hydraulically operated bottom hole pump  44  to lift fluid through standing valve  68  and force production fluid from below packer  26  through ports  64  into the annular fluid channel  28  within the casing  14  to the earth&#39;s surface. The produced fluid flows upwardly in annular fluid channel  28  and flows through open flow control valve  50 G into production flow line  46 . Power fluid passing through open flow control valve  50 D is supplied by pump pressure from the earth&#39;s surface (not shown). As shown in  FIG. 4 , production fluid is pumped to the earth&#39;s surface by down hole pump  44  hydraulically actuated by power fluid moving downwardly within tubing  22  and combined power fluid and production fluid flowing upwardly through annular fluid channel  28  as shown by the arrows. Production fluid moves upwardly through safety valve  24  and is pumped out through port  64  by pump  44 . 
     The well system remains in the condition as shown in  FIG. 4  as long as production fluid is pumped from the subterranean formation by the action of power fluid injected through power fluid flow line  48 , the power fluid returning to the earth&#39;s surface commingled with production fluid through production flow line  46 . 
     When pump  44  must be repaired or replaced, steps illustrated in  FIGS. 5–7  are followed. As shown in  FIG. 5 , master valve  34  is opened, flow control valves  50 A,  50 C,  50 D, and  50 G are closed and flow control valves  50 B,  50 E and  50 D are opened so that power fluid from flow line  48  flows in a reversed direction—that is, flows downwardly through annular fluid channel  28  through ports  64  and upwardly within tubing  22 , all as shown by the arrows. Flow upwardly in tubing  22  forces pump  44  in the upward direction. With main valve  34  open, pump  34  passes upwardly through the open valve and into pump lubricator  36 . 
     When pump  44  is safely within pump lubricator  36 , main valve  34  is closed as shown in  FIG. 6 . In like manner, flow control valves  50 B,  50 D,  50 E,  50 F, and  50 G are closed while flow control valves  50 A and  50 C are open. This permits fluid to be circulated in the direction shown by the arrows. Fluid from power fluid flow line  48  moves into an upper end of pump lubricator  36  and downwardly past pump  44 , the fluid passing out of lubricator  36  through open flow control valve  50 C and back to the earth&#39;s surface through production flow line  46 . In this way, pump  44  can be completely cleaned of crude oil since the fluid flowing past it in the condition as shown in  FIG. 6  may be water having a detergent or soap therein or other cleaning fluid by which the pump is rinsed clean. After pump  36  has been cleaned by the fluid flow paths as shown in  FIG. 6 , attachment member  62  may be lowered to grasp and remove pump latch  38  having pump  44  attached to it. The pump  44  may then be withdrawn by means of guide wires  52  and  54  up to the earth&#39;s surface where the pump can be replaced or repaired. When a new or repaired pump is to be installed, the sequence of  FIGS. 1–4  are repeated to reinstall the pump where it can be hydraulically actuated to extract crude oil from the producing formation. 
       FIGS. 1 through 7  illustrate the system of this invention in which down hole pump  44  is installed or removed by use of guide wires  52  and  54 . This is by way of example only as the pump may be removed from or placed in pump lubricator by divers or by use of remotely operated vehicles. 
     The system of the invention provides a means of installing and removing a hydraulically actuated down hole pump from a subsea location in a manner to substantially reduce contamination of the environment. 
     While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claims, including the full range of equivalency to which each element thereof is entitled.