Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/11—Perforators; Permeators
  • E21B43/116—Gun or shaped-charge perforators
  • E21B43/1185—Ignition systems
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42D—BLASTING
  • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
  • F42D1/04—Arrangements for ignition
  • F42D1/045—Arrangements for electric ignition

Definitions

• This invention relates generally to explosive well tool safety devices, and particularly to a new and improved grounding switch that can be activated to greatly reduce the possibility of accidental firing of an explosive well tool until it has been lowered below the rig floor or other area where personnel mav be present.
• the general object of the present invention is to provide a new and improved safety switch that will prevent premature firing of an explosive well tool.
• Another object of the present invention is to provide a new and improved safety switch that functions to prevent flow in of electric current to the explosive wireline tool while the tool is being handled at the surface, and until it has been positioned well below the rig floor where service personnel might be present.
• the switch apparatus includes a tubular metal bodv having a hollow interior and a side opening through the wall thereof.
• One end of the bodv has means for connecting it to a cable head to which the electric wireline is attached, and the other end of the body is provided
• An insulated conductor which couples electrical signals from the cable to the tool extends through said interior past said opening.
• the conductor has at least a portion of its insulation removed at a location opposite said opening to
• An electrical contact in the form of a metal contact plug is mounted in said opening for movement between a first position out of contact with said bare surface area, and a second position in contact therewith.
• the contact plug shorts the conductor to the body, and thus to the armor wires of the cable. Since the detonator normallv included in the explosive tool has a finite electrical resistance, current flowing toward the tool from the cable will be shorted to ground via the contact plug.
• the switch When the switch is placed in the. second or “open” position, the 5 explosive tool can be operated in the usual manner.
• the grounding switch of the present invention is placed in the "closed” position and attached to either the tool body or the cable head before the complete rig up is made, and is left in the "closed” position until the tool has been lowered into
• the upper section of the well conduit which may be casing, tubing or drill pipe.
• the explosive portion of the tool will be well below the rig floor where personnel mav be standing.
• the switch bodv is -iust above the upper end of the conduit, the operator, using an appropriate instrument l*. such as an alien wrench or screwdriver, can position the switch in its "open” position by rotating and retracting the contact plug so that it no longer engages the bare portion of the conductor within the body passage. Until this has been done, it is not possible in most cases for the explosive tool to be
• switch assemblv The physical construction of the switch assemblv and its various component parts can take various forms, and several
• Figure 1 is a somewhat schematic view of the top of a well with an explosive tool being lowered therein?
• Figure ? is a longitudinal, sectional exploded view of one embodiment of the present invention with the contact plug and 5 adapter bushing removed and shown in side elevation;
• Figure 3 is a sectional view similar to Figure 2 showing another embodiment of the present invention;
• Figure 5 is a longitudinal sectional view of a third embodiment of the present invention.
• a wireline tool 10 that includes an explosive device 11 on its lower end is shown being lowered into a well conduit 12, which mav be casing, tubing or drill pipe.
• a safety switch assembly 13 in accordance with the present invention is attached between the uppermost end of the
• the wireline 15 bodv of the tool 11 and a cable head 14 to which the electric wireline 15 is attached The wireline 15 extends upward and over a sheave 16, and then outward to the winch of a service truck (not shown) .
• a service truck not shown
• the wireline 15 that is used for running explosive tools is a monocable that has a single
• T insulated conductor wire in the center of a core, and around which metal armor wires are laid to provide tensile stren ⁇ th.
• the conductor is coupled through a collector ring and brush arrangement on the winch spool to a power circuit in the truck, such circuit being provided with a normally open firing switch
• the conductor wire 17 extends from the cable 15 down through the tool 10 to a detonator 18 for the explosive charge 11.
• the tool body and the armor wires of the cable provide a
• the wireline tool 10 is shown as having been lowered into the top of the well conduit until the safety switch 13 is located just above the rig floor 20. The tool 10 is then stopped where the switch 13 is still accessible to operating personnel. At such
• the explosive charge 11 is well below the rig floor 20 , so that even if the charge were to be accidentall y fired at this time, most personnel on the floor would be out of harm's way.
• the switch assembly 13 includes a tubular, metallic body 22 having a male end portion 23 and a female end portion 24.
• the male portion 23 has a reduced outer diameter provided with external threads 25 and seal rings 26 which are used to provide a leak-proof connection of the body 22 with the lower end of the cable head 14.
• the female end portion 24 has internal threads 30 and a seal bore surface 31 by which the body 22 is connected in a leakproof manner to the upper end of the body of the well tool 10.
• the cable head 14 has a female arrangement of threads and seal surface that preferably is identical to that of the lower end portion 23 of the switch body 22.
• the body 22 has a internal passage 32 that is intersected by a radial opening 33 through the wall of the bodv.
• the central region 34 of the passage 32 can be laterally offset toward the side of the body 22 to provide a region 35 of increased wall thickness which surrounds the side openin 33.
• a metal contact plug 36 has an inner section 37 that is arran ⁇ ed to be received in a reduced diameter inner portion 38 of the opening 33.
• An external groove in the outer wall of the inner section 37 carries an O-ring seal 40 which sealingly engages the wall of the opening 38 to prevent fluid leakage.
• the enlarged diameter outer portion 42 of the opening 33 is threaded, as shown, to receive an annular adapter 43 having a central bore (shown in dash lines) which is threaded to receive the companion threads 44 on the outer section 45 of the contact plug 36.
• the outer end surface of the plug 36 is provided with a suitable recess such as a diametrical slot, or a depression having polygonal walls, so that a suitable instrument such as a screwdriver or an alien wrench can be employed to turn the plug and advance it radially inward or outward with respect to the longitudinal axis of the body 22.
• a section of conductor wire 48 extends in a slack manner throu ⁇ h the passage 32.
• the opposite ends of the wire 48 are electricallv connected to suitable connectors, such as banana pins 49 and 50, which can be mounted on nonconductive discs 51, ⁇ 52 fixed at the respective opposite ends of the passage 32.
• suitable connectors such as banana pins 49 and 50
• the conductor wire 48 forms a section of the wire 17 shown in dash lines in Figure 1.
• a portion of the in insulation is removed from that side of the wire which faces the end surface 53 of the contact plug 36.
• the end surface 53 will engage the bare surface 55 of the conductor wire 48 and short it with respect to the bodv 22.
• the plug 36 can be advanced inward until the outer insulated side of the wire 48 is pushed against the wall surface 54 of the passage 22 to ensure a firm electrical contact between the plug and the bare surface 49 of the wire 48. To open the switch, the contact plug 36 is turned in the opposite-hand
• the passage 59 is concentric with the axis of the body 22', and has a reduced diameter mid-portion 60 that is intersected by the side opening 33.
• the opening 33 is enlarged somewhat in diameter, and the contact plug 62 has an integral threaded flange 63 at its outer end which is arranged to be received in a threaded counterbore 64 of the body 22'.
• the contact plug 62 is shown at 90° with respect to its actual
• the mid-section of the plug 62 has an external recess which receives an O-ring seal 65 that sealingly engages the wall of the inner portion 61 of the opening 33.
• the inner section of the plug 62 is provided with spaced-apart legs 66, 67 which define an opening 80
• the opposite leg 66 is similarly shaped, except that its rear surface 84 lies in such horizontal plane, and the front surface 85 curves outward to the diameter of the mid-section 83.
• the conductor wire section 68 has 5 the insulation removed completely around it for a length 69 approximately equal to the diameter of the inner opening 61, so that the legs 66, 67 straddle such bare portion 69 when the contact plug is positioned in the opening 33.
• the contact plug 62 is rotationallv oriented such that the bare wire portion 69 does not touch either of the legs 66, 67 but extends with equidistant spacing therebetween.
• the plug 62 is rotated bv a hand-held instrument through a small angle, as previously 5 described, until the edges of the surfaces 82, 85 on the respective legs 66, 67 touch opposite sides of the bare wire portion 69 to short the wire to the body 22 ⁇ of the switch.
• Suitable indicia can be provided including alignment marks on the exterior surface of the body 22' and the 0 flange 63 of the plug 62 to show at what angular position the switch is "open” or “closed”. Suitable stops (not shown) also can be provided in the open and closed positions to ensure that the bare section 69 is not yielded as the switch is operated.
• the conductor wire section 70 is formed as a relatively rigid rod having an enlarged diameter center portion 71.
• Connectors 49 and 50 are secured to the respective opposite ends of the rod 70, and non-conducting plastic sheaths, 72, 73 are provided on the respecting outer sections 74 and 75 thereof.
• the sheath 74 fits snugly inside the upper section 76 of the passage 32, and has an outer diameter substantially equal to the outer diameter of the center portion 71.
• the sheath 75 is similarlv shaped, but has an outwardly directed threaded flange 77 at its outer end which is secured in a threaded counterbore 78 in the bodv 22' '.
• the contact plug 62 having depending legs 66, 67 is identical in construction to that arrangement shown in Figures 3 and , and thus need not be further described.
• the plug 62 In the "open" position of the switch shown in Figure 5, there is clearance between all walls defining the inner peripheries of the legs 66, 67 and the external cylindrical surface 79 of the conductor section 71.
• the plug 62 is rotated through a small angle to bring edges of the legs 66, 67 into contact with adjacent outer surfaces of the section 71, thereby providing a short between the conductor rod 70 and the body 22' '.
• the contact plug 62 is first engaged in the side opening 33 and rotationallv oriented such that the opening 80 between the legs 66, 67 is aligned with the longitudinal axis of the body 22' ' . Then the conductor assembly 70, 72, 73 is inserted through the body passage and secured by the flange 77 as shown.
• a switch 13 in accordance with anv disclosed embodiment of the present invention is connected to the upper end of the bodv of the explosive well tool 10 bv engaging the threads 30 therewith.
• the contact plug 36 or 62 is rotated to the "closed” position to short the conductor wire to the body 22.
• the wireline tool 10 is then raised to the vertical by the cable 15, and then lowered into the top of the well conduit 12 until the switch 13 is located just above the rig floor 20, where lowering is halted.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Manufacturing Of Electrical Connectors (AREA)

Applications Claiming Priority (2)

Publications (2)

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Country Status (4)

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Citations (5)

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• 1989
  • 1989-08-08 WO PCT/US1989/003414 patent/WO1990001610A1/en not_active Application Discontinuation
  • 1989-08-08 EP EP19890909501 patent/EP0429512A4/en not_active Withdrawn
  • 1989-08-08 AU AU40708/89A patent/AU4070889A/en not_active Abandoned
  • 1989-08-11 CA CA 608081 patent/CA1323896C/en not_active Expired - Fee Related

Patent Citations (5)

Non-Patent Citations (1)

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