Abstract:
This invention relates generally to remotely operated well borehole or sub-sea tools for oilfield use, and more particularly, for a one shot valve useful for activating such well tools or sub-sea devices in a safe and reliable manner.

Description:
This application claims benefit of provisional application No. 60/027,419 filed Oct. 8, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to remotely operated well borehole or sub-sea tools for oilfield use, and more particularly, for a one shot valve useful for activating such well tools or sub-sea devices in a safe and reliable manner. 
     2. Background of the Related Art 
     Well services or completion tools and some sub-sea devices have been designed to operate from hydrostatic pressure. Typically, in operation such tools expose one side of a piston or operating rod to hydrostatic pressure upon receipt of a command with the opposite side of the piston being at atmospheric or a much lower pressure. The pressure differential causes the piston or operating rod to move (do work) and this motion causes the desired tool or device actuation or deployment. 
     For example, in a well working tool such as a packer, when the tool is run into the borehole on either wireline, coiled tubing or production tubing, an internal piston working in a cylinder with atmospheric pressure maintained upon either end is provided. As the tool is located in a desired position or depth in the borehole, a valve is actuated on command to expose one side of the piston or operating rod to hydrostatic well pressure. This causes a differential pressure force to be applied to the piston which, in turn, causes the piston to move. This force and movement is then mechanically coupled to perform various sub-surface functions as desired, such as setting a packer or setting a wire line locking and pack off device. 
     There is need for a safe, small, simple and reliable remotely operated electrically actuated valve for use in tools such as these mentioned above. 
     For these and other reasons, it would be desirable to have a one-shot command activated valve for activating sub-sea or well working tools which is not triggered by random electrical spikes, electrical fields from equipment, or stray ground current on the floor of an offshore platform. The present invention provides such a safe, reliable, one shot activating valve for opening a port in a well tool or sub-sea device to hydrostatic pressure. 
     In some prior art tools, pyrotechnic or explosive operated valves have been utilized. It is apparent that a differential pressure valve, such as provided in the present invention would provide a much safer device to transport, or use, in a hazardous environment. The lack of pyrotechnic or explosive substances in the operation of the present valve also renders it much less subject to regulation by governmental agencies and transportation services. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention comprises a novel one shot electrically activated valve for use in well boreholes or sub-seal tools or devices. The device comprises a normally closed valve configured to open one time and stay open. The valve has an inlet port or ports and outlet port or ports, normally closed, and is insertable into a host device or tool to be pressure activated by opening the inlet and outlet port or ports to communicate hydrostatic pressure to the host tool. The valve has a body member and shiftable valve means, movable relative to the body member, and having sealing members to initially block fluid passage from the inlet port to the outlet port in the closed position and to allow passage of fluid (pressure) from the inlet port to the outlet port in the open position. The shiftable valve is spring and pressure biased to the open position. Prior to activation, it is held in the closed position by a low temperature meltable retaining pin or plug. Upon command, electrical current is conducted to a heating coil encompassing the retaining plug or pin in order to raise its temperature above its melting point. This then releases the shiftable valve which, assisted by spring and pressure bias, moves to the open position. 
     The invention may best be understood by reference to the following detailed description thereof, when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are intended as illustrative of one preferred embodiment of the present invention. They are intended to be illustrative and not as limitative of the invention. 
     FIG. 1 is a schematic side view in cross section of an actuating valve in accordance with concepts of the invention. 
     FIG. 2 is an enlarged schematic side view of a portion of the actuating valve of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIGS. 1 and 2 jointly, a preferred embodiment of a valve employing concepts of the present invention is shown schematically in a side sectional view. The valve is shown in its normally closed position in FIGS. 1 and 2. It is configured to actuate or open one time and then stay open. 
     The valve comprises a generally cylindrical shaped body member  1 , which is sized and configured (as by external threads, not shown) to be inserted and attached into a host sub-sea or well working tool or device. Body member  1  has external elastomeric O-ring seals  10  disposed in grooves on either side of an inlet port  16 , for sealing the bore of the host tool recipient of the valve. Fluid pressure is supplied to the host tool via outlet port  17  when the valve is actuated as will be discussed. 
     A movable plunger member  2  is sized to be received in and fit into a longitudinal bore  16 A in the body member  1 . A coil spring  9  captured between a shoulder  16 B of plunger  2  in bore  16 A and an enlarged diameter head portion  2 A of plunger  2 , biases plunger  2  to the left (or open) position in the drawing. A thermal insulator member  4  which bears on and is restrained by an electrically activated release mechanism (shown in the circle generally at  8  and enlarged in FIG.  2 ). The plunger  2  is urged to the open position by two means, a coil spring  9 , just discussed, and by a pressure bias means. Both means are provided to assure reliable operation at either low or high hydrostatic (pressure) differentials to overcome O-ring friction. The diameter of plunger O-ring seals  11  are larger than that of plunger O-ring seals  12 . This causes a hydrostatic pressure bias (opening force) to be applied to plunger  2  via borehole or sea fluid pressure conducted to plunger  2  by ports  16  which is proportional to the product of the difference in the cross sectional area of the plunger bore  16 A at seals  11  and  12  and the differential (hydrostatic) pressure across the seals. O-ring friction normally increases with increasing pressure differential. By sizing seals  11  and  12  properly, an opening force may be provided that is always greater than the plunger O-ring friction regardless of pressure differential. 
     A cap  3  is threadedly attached (not shown) to the body member  1 . The releasing mechanism comprises a meltable or fusible plug or pin member  7  contained inside a heat conducting cylinder  19  of anodized aluminum or the like. A heater coil  20  of turns of resistance wire  21  is wound about the cylinder  19  and connected to electrical power wires  15  which provide electrical current thereto. A partition  22 A separates a void space  23  in cylinder  19  from the meltable or fusible plug  7 . The heater wide  21  coil straddles the partition  22 A in cylinder  19 . A hole  22  in the partition  22 A provides fluid communication into void space  23  which has its opposite end open. Thus, when the fusible or meltable plug member  7  is rendered liquid, or otherwise pliable, it can flow under the pressure of opening forces described above into void space  23  and into bore  24  inside cap  3  allowing lateral motion of plunger  2  into the “open” position. 
     The fusible or meltable plug member may comprise a suitable tin/lead alloy or bismuth alloy or antimony alloy chosen to provide mechanical compressive strength, but having a relatively low (500° F. to 1000° F.) melting point and high creep resistance at high temperature, preferably up to its melting point. 
     In operation, the valve enters the operating environment in the closed position as shown. Seals  10 ,  11  and  12  prevent fluid passage (and pressure communication) from input port  16  to output port  17 . The spring  9  and hydrostatic pressure bias incorporated into plunger  2  operate to bias the plunger left (open position). When it is desired to open the valve, an electrical current is applied via conductors  15  and cause heater coil  20  to heat and to melt the fusible plug  7 . Plug  7 , now liquefied, is displaced via hole  22  into the heated void space  23  and/or bore  24  allowing the plunger  2  and insulator  4  to move to the left. This in turn opens inlet port  16  to outlet port  17  communicating fluid and hydrostatic pressure to the host tool or device for its operation. 
     This device provides numerous desirable features such as: Valve actuation may be initiated on command from an electrical source. Short duration electrical spikes or stray ground currents will not accidentally actuate the valve. The valve shifts one time and stays open regardless of additional electrical inputs. The valve has a small size suitable for down hole borehole uses. The configuration operates reliably at temperatures up to 350° F. and pressures up to 15,000 PSI. The valve is safe to handle and to transport. Sealing of ports is positive with no leakage. Required actuation power is low and suitable for battery driven operations. More reliability can be provided than solenoid operated valves due to greater forces being applied by the combination of hydrostatic and spring opening biases provided by the design. 
     The foregoing descriptions may make other arrangements and embodiments apparent to those of skill in the art. The aim of the appended claims is to cover all such changes and modifications that fall within the true spirit and scope of the invention.