CA1293296C - Apparatus for electromagnetically coupling power and data signals between well bore apparatus and the surface - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
In the representative embodiment of the new and improved apparatus disclosed herein, a downhole tool adapted to be coupled in a pipe string and positioned in a well bore is provided with one or more electrical devices cooperatively arranged to receive power from surface power sources or to transmit and/or receive control or data signals from surface equipment. Unique inner and outer coil assemblies arranged on ferrite cores are arranged on the downhole tool and a suspension cable for electromagnetically coupling the electrical devices to the surface equipment so that power and/or data or control signals can be transmitted between the downhole and surface equipment.

Description

Z~6 APPARATUS FOR ELECTROMAGNETICALLY COUPLING POWER AND DATA
SIGNALS BETWEEN WELL BORE APPARATUS AND THE SURFAC~

BACKGROUND OF THE INVENTION
Various systems have been proposed heretofore for transmitting data and/or control signalq as well as electrical power over one or more electrical conductorQ interconnecting the surface equipment and ~ub-~urface apparatus such as perforating gun~, various downhole mea~uring de~ices, or controls for subsea well hesds. Those skilled in the art will appreciate, how~ver, that when the 3ub-surface apparatus i~ located in a pipe string it i~ difficult to pro~ide a continuous trouble-free electrical communication path between the sub-surface apparatus and surface 10 equipment. The 9imple9t technique is, of course, to dependently couple the sub-~urface apparatus to an electrical cable and then temporsrily remo~e the apparatus and its supporting cable from the pipe strin8 each time that a pipe ~oin~ is to be removed or added to the pipe string. This ~traight-forward technique is 15 particularly useful for stationing a measuring instrument in a tubing qtring in a completed well bore and thereafter obtaining measurements a~ d~sired. Nevertheless, when this technique is used to make varioua measurementQ during the course of a typical drilling operation, there will be a significant increase in the ; 20 amount of time required to carr~ out e~en the simplest downhole mea~urement. An example of this time-consumlng technique is seen in U.S. Patent No. 3,789,936.
Accordingly, to mi~imize ~he number of times that a measuring device has to be re=oved from the drill strin8 during a .

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drilllng operation, as shown, for e~mple, in U.S. Patent No.
3,825,078, it ha3 been proposed to support measuring instruments by an electrical cable ehat has an upper portion of considerable exce~ lengeh that i9 arranged in one or more doubled loops in the upper portion of the drill string. A similar arrangement i9 ~een in U.S. Patent No. 4,416,494 where the extra portion of the cable is instead coiled wi~hin a special container disposed in the drill string. In either case, b~ arranging an electrical connector on the upper end of the cable, the upper end portion of the cable can be quickl~ disconnected from the surface equipment.
In thi~ manner, the upper end portion of the csble can be readily passed through a pipe joint that i3 either being remo~ed from or added to the upper end of the drill string. The cable is then reconnected to the surface equipment and the drilling operation is again resumed. Additional sections of cable are periodlcally added to the upper porti~n of the cable to increase the orerall length of the cable as the drilling operation continues to deepen the borehole. Deapite the time-~aving features offered by these complicated handling technique~, there i9 clways a chance that the ex~rs cable portlon will become twisted or entangled within the drill pipe. Moreover, ~ince additional cable seceions are coupled to the main cable, there will be an increasing number of electrical connector~ in the drill s~ring which are ~qubjected to the adYer~e effects of the drillin~ mud pas~ing through the drill ~tring.
To aYoid the handling problems presented b~ a csble ehat l~ loo~ely disposed within a pipe string, it ha~ also been ~932~;
propo~ed ~o provide an 21ectrical conductor that is secured to or mounted in the wall of each pipe joint. For example, as shown in U.S. Patent No. 2,748,358, a short length of electrical cable i3 arrsnged in e~h pipe joint and supported therein by way of an electrical connector that is coaxially mounted in an upstanding position just inside of the female or so-called "box end" of the pipe joint. The lower end of the cable is unreQtrained and is allowed to hang just below the so-called "pin end" of the pipe joint so that ~he electrical connectors can be mated and the pipe string assembled or disassembled without undul~ disturbing the cable length~ or their mated connectors. Similar arrangements are di~closed in U.S. Patent No. 3,184,698 and U.S. Patent No.
3,253,245. Another proposed arrangement ~hown in UOS. Patent No.
4,399,877 utilizes a so-called "side-entry sub" which i9 coupled in the pipe string and has an openLng in one side wall through which an electrical cable can be passed.
In the system~ shown in the several aforemen~ioned patents, their respective electrical connectors mu~t be manually connected a~ pipe strin8 is moved into the well bore. To a~oid wasting the time required for manuslly connecting a large number of connectors, 88 shown in U.S. Patent No. 4,095,865 and U.S.
Patent No. 4,220,381, it has been proposed to al~o provide matin8 contacts ln the ends of each of the pipe joints which wi~l be automatlcally connected as the pipe joints are coupled together.
~ith either of these de3i8n arrangements, it will, of course, be appreciated th~t there i8 alwa~ a substan~ial risk that one or more of the connectors requlred to interconnect 80 many short 9 ~zg329~
cables will be ad~ersely ~ffected by the well bore fluids.
In view of the many problems typically a~sociated with electrical connectors, it has been proposed to instead pro~ide i~dUctive couplings on the opposite ends of the pipe joint3 for interconnecting the cableA in each pipe joint. U.S. Patent No.

2,379,800, for example, show~ a typical set of induction coils that are respectively wound on annular soft-iron cores moun~ed in opposing rece~ses on the ends of each joint and cooperatively arranged ~o that whenever the pipe joint~ are tandemly coupled together each pair of coils will provide a transformer coupling between the cables in tho~qe pipe joints. U.S. Patent No. 3,090, 031, for example, attempts to overcome the inherently-high 10~3es of conventional transformer couplings within typical oilfield piping by pro~iding an encapsulated transistorized amplifier and power source at each as90ciated pair of inductive windings.
To avoid the variou~ problems discussed above, it has also been proposed to mount one or more measuring de~ices in the lower end of the pipe string and inductiYely couple these devices to an electrical cable that i3 lowered through the pipe string to the downhole measuring de~ices. For in~tance, as seen in Figures 2 and 7 of U.S. P~tent No. 2,370,818, a mea~uring device which is mounted in a drill collar coupled to the lower end of the drill strlng i8 prorided with an output coil that i8 coaxially disposed in an annular rece3s around ~he inner wall of the drill collar.
The output signals are transmitted to the surface by wa~ of an electrical cable having a matching coupli~g coil on its lower end ~hat is wound around a central ferromagnetic core member arranged ~329~

to be complementally fitted into the output coil on the measuring device.
U.S. Patent No. 3,209,323 discloses a similar measuring s~stem having 8 ~easurin8 deYiCe which is adapted to be mounted on the lower end of a drill string and cooperatively arranged for transmitting signals to and from the surface by way of a matched pair of induction coils which are respectivel~ arranged within an upstanding fishing neck that is coaxially disposed in the drill collar on top of the measuring device and a complementally-sized overshot that i~ dependently su~pended from a t~pical electrical cable. Although this particular arran8ement eliminates many of the problemq discussed above, it will be recognized that ~ince these induction coils are surrounded by thick-walled drill pipe, a significant amount of electrical energy that could otherwiqe be trsnsferred through these coils will instead be dissipated into the electrically conductive pipe. Thu~, it will be appreciated by those skilled in the art that with this prior-art arrangement, the unavoidable 1099 of electrical energy will be so great that the system simply cannot transmit signals to and from the surface unless these coils are closely fitted together. This need for a close fit between these induction coils will, therefore, make it difficult to lower the overshot through th`e drill s~ring with any assurance that it can be reliably positioned around the fishing neck. Moreover, in those situations where well bore debris has accu~ula~ed around the up~tandlng fishing neck on the meaeuring device b~fore the overshot i8 lowered into the drlll string, ~he debris could make it difflcult or impos~ible to properly po~ition ~Z~32~

the overshot on the fishing neck.
The ~arious problems associated with the several data-transmi~sion systemq discussed in the aforementioned patents are simllar in many re~pects to the problems associated with coupling a surface power source to a typical oilfield perforating device.
Accordingly, as seen in U.S. Patent No. 4,544,035, a perforating gun that is adapted to be run into a well on the lower end of a tubing string is provided with an inductive coupling arrangement that i9 generall~ ~imilar to the coupling arrangement disclosed in the above-mentioned U.S. Patent No. 3,209 9 323.
Despite the prolifera~ion of patents in~olving various system3 of this nature it is readily apparent to those skilled in the art that none of the ~y~tems discussed above for transmitting signals and/or power between the ~urface and downhole de~ices in a pipe string have been commercially ~uccessful. In~tead it has been necessarg heretofore either to use a continuous electrical cable that is directly connected to the downhole equipment for transmitting da~a and power or to utilize a so-called measuring-while-drilling or "MWD" tool with a self-contained power supply which is cooperati~ely arranged for sending data to the surface b~ transmittlng acoustlc signals through the drill string fluid.

OBJECTS OF THE INVENTION
Accordingly, lt i9 an object of the present invention to pro~ide new and improved apparatus for reliably trsn~mitting power and/or data between the surface snd well bore apparatus.
It is a further ob~ect of the inqention to provide new :1;29~Z9~

and improved well bore apparatus having electromagnetic coupling means cooperatively arranged fo~ efficiently transferring power and~or data between one or more Yurface and downhole electrical d~ices without undul~ restricting the passage of other well bore equipment or tr~atment fluids through the downhole appsratus.

SUMMARY OF THE INVENTION
This and other objects of the preQent inYention are attained by providlng well bore appQratus with new and improved : electromagnetic coupling means having inner and outer induction coils ~hich are cooperatively arranged and adapted so that one of the coil~ can be dependently suspended from a well bore cable and connected to electrical conductors therein whereby the one coil can be moved between 8 remote position separated from the other coil to a ~elected operating position in a well bore where the 15. coil9 will be c08xi811y disposed in relation to one another for inductively coupling surface equip~e~t connected to the cable conductors to well bore appflratu~ connected to the other coil.
The colls are uniquely arran8ed on inner and outer cores formed : of suitable ferrite materials thereb~ enabling these eoil~ to be radially spaced by a subctantial distance from each other aq well as to tolerate e~treme radial and longitudinal misalignments without untuly affecting the efficient transfer of electrical energy~between the surface and well bore apparatus, ~z~z~

According to a broad aspect of the invention there is provided well bore apparatus comprising:
a sub-surface tool including a selectively-operable means which includes at least one electrical device;
coupling means including inner and outer telescopically-inter~itting coil a.ssemblies, said coil assemblies further including~
inner and outer cores formed substantially of ferrite materials having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively arranged so that said coil assemblies can be telescopically inkerfitted together, said ferrite material being selected from the group of metal ions consis~ing of manganese, nickel, zinc, maynesium, cadmium, cobalt, and copper and having a cur.te temperature point greater than ~he maximum anticipated well bore temperature to which sald coil assemblies will be exposed, said ferrite materials further including an additive of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer cores, respectively wound around said 1nner and outer cores and electromagnetically intercoupled to one another whenever said coil assemblies are telescopically interfitted together, means on said tool for retaining one of said coil assemblies in a position in a well bore where it can be telescopically lnterfitted with the other of said coil assemblies, and means for connecting said coil o~ said one coil assembly to said electrical 7a ~3~`~ 70261-54 device; and means on said other coil assembly for connecting its said coil to the conductors in a suspension cable supporting said other coil assembly for movement in a well bore to said position where said coil assemblies are telescopically interfitted.
According to another broad aspect of the invention there is provided well bGre apparatus comprising:
sub~surface equipment including a tubular body adapted to be coupled into a pipe strlng and positioned in a well bore;
selectively-operable means on said body including at least one electrical device:
coupling means including inner and outer telescopically-interftttiny coil assemblies, said coll assemblies further including, inner and outer core members respectively formed substantially of ferrlte materials having a DC bulk reslstivity greater than ten thousand ohm-meters and cooperatively sized and arranged so that said coil assemblies can be telescopically interfitted together, said ferrite materials being selected from the group of metal ions conslsting of manganese, nickel, zinc, magnesium, cadmium, cobalt and copper and having a curie temperature point greater than the anticipated maximum well bore temperatures to which said coiI assemblies will be exposed, said ferrite materials further including an addi~ive of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and .
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inner and outer coils, disposed within said inner and outer core members, respectively wound around said inner and outer core members and electromagnetically intercoupled to one another whenever said coil. assemblies are telescopically interfitted toyether, means for coaxially mounting said outer coil assembly within said body and in position to telescopically receive said inner coil assembly, and means for connecting said outer coil to said electrical 0 device;
means on said inner coi.l assembly for connecting said inner coil to the conductors in a suspension cable dependently supporting said inner coll assembly for movement though a pipe string ln a well bore to a position therein where said inner and outer coil assemblies are telescopically interfitted; and surface equipment connected tot he conductors in a suspension cable supporting said inner coil assembly.
According to another broad aspect of the invention there is provided apparatus adapted to be disposed in a well bore for inductively coupling power and data signals between surface equipment and sub-surface equipment, comprising:
a first conductor adapted to be connected to the surface equipment;
a second conductor adapted to be connected to the sub-surface equipment; and coupling means interconnecting said first conductor to said 7~

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second conductor for conducting said power and data signal between said surface equipment and said sub-surface equipment, said coupling means including, a first coil connected to said first conductor, a second coil connected to said second conductor and coaxially disposed around said first coil, said second coil being inductively coupled with said first coil, and core means disposed within and around said first coil and said second coil for assisting in ~he inductive coupling of said first coil and ~aid second coil, said core means comprising a specific ferrite material, saicl specific ferrite material of said core means includlng ceramic magnetic materlals formed of lonic crystals and having the general chemical composition (Me)Fe203, where (Me) ls a metal ion selected from a group consisting of manganese, nickel and zlnc.
According to another broad aspect of the invention there is provlded apparatus adapted for electromagnetically coupling electrlcal conductors in a well bore ~uspension cable to well bore apparatus havin~ at least one electrical device and comprising:
lnner and outer coil assemblies respectively including, inner and outer core members formed substantially of ferrite materials having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively arranged so khat said inner coil assembly can be telescopically disposed within said outer coil assembly, said core members being formed of ferrites selected from the group of metal ions consis~ing of manganese, nickel, zinc, magnesium, cadmium, 7d ~2~3Z9~

cobalt and copper, said ferri~es further including an additive of up to about ten percent by weight of zirconia, and inner and outer coils disposed within said inner and outer core members, respec~ively wound around said inner core member and inductively coupling the conductors in a suspension cable connected to one of said coils to a well bore electrical device connected to the other of said coils whenever said inner coil assembly is disposed within said outer coil assembly.
According to another hroad aspect of the invention there is provided apparatus adapted for electromagnetically coupling electrical conductors in a well bore suspension cable to well bore appa.ratus having at least one electrical device and comprising:
lnner and outer coil assemblies respectively including, inner and outer core members Eormed substantlally of ferrite materials havlng a DC bullc reslstivity greater than ten thousand ohm-meters and cooperatively arranged so that sald lnner coll assembly can be telescopically disposecl within said outer coil assembly, said core members being formed of ferrites selected from the group of metal ions consistin~ of man~anese, nickel, zinc, maynesium, cadmium, cobalt and copper respectively having a curie temperature point that is at least equal to the maximum anticipated well hore temperatures to which said coil assemblies will be exposed, said ferrites further including an additive to the ferrite material of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer 7e ~293;~

core members, respectively wound around said inner core member and lnductively coupling the conductors .tn a suspension cable connected ko one of said coils to a well bore electrical device connec~ed to the other of said coils whenever said inner coil assembly is dlsposed within said outer coil assembly.
According to another broad aspect of the invention there is provided apparatus adapted for electromagnetically coupling electrical conductors in a well hore suspension cable to well bore apparatus having at least one electrical device and comprising:
inner and outer coil assemblies respectively including, inner and outer co.re members formed substantially of ferrite material having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively arranged 90 that said inner core assembly can be telescopically dlsposed within said outer coil assembly, said core members being formed of ferrites elected from the group consisting of nickel-zinc ferrite, iron oxide maynetite, nickel ferrite and magnesium ferrlte and respectively having a curie temperature point that is at least equal to the maximum anticipated well bore temperatures to which said coil assemblies will be exposed, said ~errites further includlng an additive to the ferrite material of no more than about ten percent by weigh~ of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed wi~hin said inner and outer core members, respectively wound around said inner core member and inductively coupling the conductors in a suspension cable connected to one of said coils to a well bore electrical device 7f `
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connected to the other of said coils whenever said inner coil assembly is disposed within said outer coil assembly.

7g 32~36 BRIEF DESCRIPTION OF THE DRAWINGS
The novel features of the present invention are set forth with particularitg in the appended claim3. The invention, together with further objects and Qdvantages thereof, may be best understood by way of illustrAtion of the following description of exemplary apparatus emplo~ing the principle~ of the invention as illustrated in the accompanying drawings, in which:
FIGURE 1 schematically illustrates new and improved coupling means arranged in accordance with the principles of the pre~ent invention and which is depicted a~ it may be t~pically employed with an inner portion of the coupling means dependently coupled to the lower end of a typicsl suspension cable which haA
been lower~d into a cased well bore for cooperatiYely posi~ioning the inner portion of the ccupling means within an outer portion thereof mounted on top of typical well bore apparatus that has been previously positioned in the well bore;
FIGURES 2A-2C are successive cross-sectional views of a preferred embodiment of well bore appara~us employing the new and improved coupling means of the invention;

FIGURE 3 is a ~chematic diagram of typical surface and sub-surface equip~ent ~uch QS mar be used in conjunction with the well bore zpp~ratuq shown in FIGURES 2A-2C; and FIGURE 4 depicts a typical voltage waveform that may appear acrosq the new and improved coupling mean~ of the present invention during the course of a typical operation of the well bore apparatu~ shown in FIGURES 2A-2C.

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DETAILED DESCRIPTION OF THE INVENTI.ON
Turning now to FIGURE 1, a preferred embodiment of the new and improved coupling means 10 of the present invention i9 schematically deplcted as it ma~ appear when used for coupling a typical sub-surface device or well bore tool 11 to its related surface equipment 12 that are interconnPcted by a typical well bore suspen~ion cable 13 that i9 suited for tran~mitting power and/or electrical data or control signals between the sub-surface and ~urface apparatus. It must, however, be understood that the coupling means 10 of the pre~ent in~ention may be cooperatively employed with an~ suitable electri~al cable for interconnecting variou3 types of ~ub surface device~ and their associated surface equipment.
To illustrate a typical situation in which the coupling means 10 may be effectively utilized, the sub-surface apparstus 11 i~ shown as comprising a typical tubing-conveyed perforating and testing tool such as described, for example, in U.S. Patent No. 4,509,604. As is customar~ with such tubing-conveyed tools, the tool 11 was previously coupled to the lower end of 8 joint of steel tubing 14 which was then lowered into a cased well bore 15 by successively assembling 8 tubing strlng 16 from a sufficient number of Joints for psql~ioning the perforating and testin8 tool ad~acent to an ear~h format~on 17 containing producible connate fluids. As depicted, the tool 11 includeQ a test Yalve assembly 18 (such as shown in U~S. Rei~sue Pa~ent No. 29,638~ thst has a full-bore valv0 element 19 which i8 ~electiYel7 opened and closed : in re~pon e to chsnge~ in ~the pressure of the fluid~ in the well ~3~

bore 15 for controlling fluid communication through the tool and tubing ~tring 16.
The lower end of the test valve 18 i8 cooperatiYely arranged to be coupled to a full-bore packer 20. Those skilled in the art will, of course, appreciate that for the preferred arrangement of the tool 11, the packer 20 is a permanent packer having normally-retracted slips and packing elements that i~ set in the cased well bore 15 just above the formation 17. With the depicted arrangement, once the packer 20 has been independently ~et in ~he well bore 15, the perforating and testing tool 11 is lowered into the well bore. A~ i~ typical, once the tool 11 ha~
reached the pac~er 20, the valve 18 i9 fluidly coupled thereto b~
mean~ such as a reduced-diameter seal nipple (not illustrated3 that i9 dependentl~ coupled to the test valve and adapted to be sealingly disposed within an upwardly-opening seal bore in the packer mandrel.
As depicted, the perforating and testing tool 11 al~o include~ a slotted tail pipe 21 th~t i~ dependently coupled below the reduced-diameter seal nipple and appropriately arranged for dependently qupporting a perforating gun 22 carrying one or more typicsl perforating deYices such a~ Rhaped charges (not depicted) which, when detonated~ will produce a corre~ponding number of perforations, as at 23, for communicating the earth formation 17 witb the isola~ed in~erval of the well bore 15 below the packer 20. It will, of cour~e, be realized that once the perforating gun 22 has been actuated, the tes~ qalve 18 is then selectivel~
operated for controlling the fluid communication between the 3L~''~3;~9~

isolated interval of the well bore 15 and the tubing ~tring 16.
To illustrate a typical situation in which the coupling means 10 may be effecti~ely utilized, the perforating and testing to~l 11 i9 depicted a~ including measurement means, a~ generally indicated at 24, preferably arranged in one or more thick-walled tubular bodies 25 and 26 tandemly coupled between the lowermost pipe joint 14 and the test valve 18. As i9 typical, ~he various components of the measurement mean~ 24 are cooperatively arranged in the walls of the tubular bodies 25 and 26 thereby providing an unobstructed or co-called "full-bore" flow pas~age 27 through the full length of the tool ll.
It should ba appreciated that since the coupling means lO of the pre~ent invention are not limited to only certain types of measurements, the measurement means 24 may include one or more trpical measuring devices and associated electronic circuitr~, as at 28, adapted for measuring such fluid properties or well bore char~cteristics a9 the pressures and/or temperatures of fluids abo~e and below the packer 20 as well as the conductivity, flow rate and denslty of the~e fluids. The me~surement meAns 24 may include batterie~ 29 for powerin~ the measuring device~ and their circuitry 28 as well a8 one or more self-contained recorders 30 for recordi~g the output data from these deYices over extended periods~
As will b~ subsequently de~cribed in Breater detail by 25 reference to FI6UR~S 2A-2C, the preferred embodi~ent of the new and impro~ed coupling means 10 of the pre~ent invention includes a unique outer coil assembly 31 cooperatiYely arran8ed in the ~93Z~6 upper portion of the perforating and testing tool 11. Although the coil as~e~bly 31 could b~ suitably mounted in the upper end of the thick-walled tubular body 25, it is preferred to instead arrange the outer coil assembly within a reduced-diameter tubular member 32 having a longitudinal bore defining an extension to the axial pa~sage 27 through the bodies 25 and 26. The member 32 is coaxially mounted in an outer tubular body 33 having an enlarged bore that is appropriately cized for cooperatively po~itioning the outer coil assembly 31 around the axial passage 27 as well as for providing a fluid bypas~ pas~age 34 around the coupling means 10. One or more electrical conductors (not seen in FIGURE l) are disposed in one or more interconnecting passages (not depicted) in the bodies 25, 26 and 32 and cooperati~ely arranged to connect the outer coil as~embly 31 in the upper body to the components of the measurement means 24 in the lower bodies.
The coupling means lO also include a unique inner coil assembly 35 coaxiall~ mounted on a wireline-supported tool or so-called "running tool" 36 that ~ sized to pas~ freely through the tuhing string 16 dnd the respective portions of the axial pasRage 27 through the tubular bodies 25, 26 and 32. The running tool 36 is arranged to be depsndentl~ coupled by a typical cable head 37 to the lower end of the suspen~ion cable 13 that i~ spooled on a winch (not illustrated in FIGURE 1) located at the ~urface And ~rra~ged for ~oving the runn1ng tool through the ~ubing string 16 between the 9urface and it9 depicted operating position in the inner body 32 where the inner coil a~sembly 3S i~ positioned in effective electromagnetic inductive proximit~ of the outer coil 3Z~

assembly 31. One or ~ore conductors (not shown in FIGURE 1) are arran~ed in the running tool 36 for cooperatively connecting the inner coil assembly 35 to ~he conductors in the 4uspension cable 13 to electrically interconnect the running tool and the surface 5 equipment 12.
Turning now to FIGURES 2A-2C, successive longitudinal cross-sectional views are shown of a preferred embodiment of the coupling means 10 of the invention. As seen generally ~t 38, the running tool 36 includes an elongated body which extends the full 10 len8~h of the tool. It will, of course, be ~ppreciated bg those skilled in the ar~ that to simplify the fabrication as well a3 the assembly and maintenance of the running tool 36, the body 38 i~ necessarily compri~ed of a plurality of individual components or interconnected assemblies.
It will, of course, be appreciated that whenever there i8 a significAnt upward flow of 1uids through the tubing string 16, such as when connate fluids are being produced from the earth formation 17 (FIGURE 1), the wireline tool 36 must be releasably secured in its establishcd operating position in the tubular body 32 to be cereain that the coil assemblies 31 and 35 are reliably maintained in effective electromagnetic inductive proximity in relation to each other. Accordingly, in the preferred embodiment of the coupling means 10 of the invention depicted in FIGURES 2A-2C, as shown gen~rally at 39 an inwardly-facing recess i~ formed 25 around the internal wall of ehe ~ubular body 32 and appropria~ely configured for defining one or more spaced oppo ed shoulders 40 and 41 that are located A predetermined dis~ance abo~e the outer 1~3~
coil assembly 31.
The wireline-supported tool 36 i8 further provided with selectively-operable anchoring means 42 that are cooperatively arran~ed and adapted to releasably secure the wireline tool in the inner tubular body 32. In the preferred embodiment of the running tool 36 ~hown in FIGURES 2A-2C, the anchoring means 42 include an elongated sleeve 43 that is slidably mounted around a reduced-diameter portion 44 of the tool body 38 and secured from rotating in relation thereto in a typical fashion by one or more ke~5 or splines and mating longitudinal grooves (not seen in the drswings) on the inner and outer members~ The lower end of the elongated sleeve 43 i~ cooperatively arraDged for supporting two or more depending flexible collet fingers 45 which are spa~ially disposed around the tool body 38. Although separate fingers may be mounted on the sleeve 43, the collet fingers 45 are preferably arranged as depending integral extensions of the sleeve which are formed by cutting away sufficien~ metal from the lower portion of the inner sleeve to enable the fin~ers to flex inwardly. Lugs or flat keys 46 sre respectively ~ecured in upri~ht positions on the free ends of the fin8ers 45, with the outer edges of these key~
being appropriately shaped to be complementally fitted within the inwardly-facing recess 39 whenever the wireline coupling tool 36 is positioned within the tubular bodg 32. To prevent the keys 46 from being twi~ted or tilted rela~ive to their re~pective collet 25 fin8ers 45, a protec~ive outer sleeve 47 haYing a corresponding : number of longitudinal slot~ 48 is coaxially ~oun~ed around ~he inner sleeve 43 and the keys are respectivel~ arranged in thesP

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slot~ for moving laterally between their illustrated normal or "extended" positions where the ~haped outer edges of the keys are projecting beyond the external surface of the outer sleeve and a "retracted" position where the outer edge~ are fully confined within the outer sleeve.
As shown in FIGURE 2~, the anchorlng means 42 further include blasing means such as an elongated coil spring 49 that i3 cooperatively arranged between the inner sleeve and a shoulder 50 on the upper end of the body 38 for urging the sleeves 43 and 47 downwardly in relation to the body from an elevated "running-in' position toward the lower "locking" position illu3trated in the drawings whenever the sleeve~ are free to move in relation to the tool body. The portion of the tool body 38 that will be disposed immediately behind the ke~s 46 whene~er the slPeves 43 and 47 are elevated running-in position is reduced or recessed by providing a corresponding number of outwardly-opening longitudinal grooves 51 that are resp2ctivel~ adapted to receive the rearward portions o~ the ke~ and the flexible collet fingers 45 whenever they are Porced inwardly from their extended positions to their respective 20 retracted posi~ion9 in the grooves. On the other hand, it will be further appreciated from FIGURE 2B that whenever the biasing action of the spr~ng 50 has shifted the sleeve~ 43 and 47 further downwardly along the eool bod~ 38, the rearwsrd edges of the keys 46 will then be posltloned directl~ over an enlarged portion 52 25 of the tool bod~ that i~ cooperatively sized to prevent the key~
from moving inwardly toward the tool body. Accordingly, ~henever the ~leeves 43 and 47 sre in their elevated position~ the collet ~29329~i fingers 45 can deflect inwardly for retracting the keys 46 from the recess 39 in the tubular bod~ 32; but whenever the sleeves are in their lower "locking" position, the keys are blocked from moving out of the recess.
The anchoring means 42 further include means, such as shown generally at 53, selectively operable from ~he surface for controlling the movement of the inner sleeve 43 in relation to the tool body 38. Accordingl~, in the preferred embodiment of the wireline tool 36, an inwardly-facing annular recess 54 i5 arranged in the inner sleeve 43 for rotatabl~ supporting a short sleeve 55 carrying an inw3rdly-directed J-pin 56 that iq movably disposed in a typical continuou~ J-slot ~ystem 57 cooperativel~
arranged on the adjacent surface of the tool body 38. Those skilled ln the art will, of course, appreciate that when the ke~s 46 are disposed withiu the reces~ 39 in the tubular bod~ 32, the sleeves 43 and 47 are secured against moving longitudlnally with respect to the tool body 38 and the weight of the tool body will be fully supported by the spring 49 when tension is removed from the cable 13. Thus, by operating the winch (not depicted in the drawing9) at the surface to slack off the suspension cab~e 13, as the tool bod~ 38 i8 mo~ed downwardly, a first inclined portion 58 of the continuous J-slot system 57 ls shifted along the J-pin 56 and thereby turns the sleeve 55 in relation to ehe tool body 38 from it~ depicted angular position to a second angular position where the J-pin is then positioned above ~he upper end of an elongated longitudinal poreion 59 of the J-slot system. At that angular po~i~ion of the sleeve 55t when tension is applied ~o the 3 ;2~3Z9~
cable 13~ the biasing action of the spring 49 will then shift the outer sleeves 43 and 47 and the collet fingers 45 downwardly as the tension on the cable simultaneously moves the tool body 38 upwardly in relation to the J-pin 56. Once this takes place, the wireline tool 36 will be locked in position within the tubular body 32 so long as tension is maintained on the su~pension cable 13.
It will 9 however 9 be appreciated that the wireline tool 36 can be released by simply ~lackiag off the suspension cable 13 ~o that the weight of the running tool will again be supported on the 3pring 49. Once thiq ~akes place, the weight of the tool 36 i~ sufficient to move the tool body 38 downwardly in relation to the sleeves 43 and 47 which will a8ain position the enlarged body portion 52 below the 810ts 48 90 that the rearward ed8es of the collet fingers 4S and the keys 46 are again free to be retracted into the recesses 51. As the tool body 38 moves downwardly, a second inclined portion 60 of the J-slot system 57 functions for turning the sleeve 55 to u third angular position where the J-pin 56 i8 positioned in the upper end of the second inclined portion~
Once the J-pin 56 i8 in this portion 60 of the J-slot system 57, reapplication of tension on the cable 13 will again rotate the Qleeve S5 to its initial position and thereby return the J-pin 56 to the first portion 58 of the J-~lot system 57. Once the sleeve 55 is in its initi~l angular poqitlon, the collet fingers 45 and the key~ 46 are able to be retracted. Thus, whenever tension is applied to the suspension cable 13/: the upper inclined shoulder~
61 of the keys 46 will engage the opposed surface~ 40 in the body ~93;~

32 and urge the keys inwardly a~ the wireline running tool 36 is initially moved upwardly in th0 pipe string 16 to return the tool to the surface.
Turning now to FIGURE 2C, the lower portion of the sub-surfacP apparatus 11 ~hows a preferred arrangement of the outerand inner coil asqemblie~ 31 and 35 of the coupling means 10 of the present inrention. As previously discussed, the outer coil assembly 31 is cooperatively mounted in a tubular body or sub 32 that is tandemly coupled in the tubing string 16, with the coil a9~embly being coaxially disposed around the axial passage 27 in the body. In the preferred embodiment of the outer coil as~embly 31, a multi-turn winding 62 of an insulated conductor or wire is srran8ed in one or more lsyer~ of uniform diameter inqide of ~
unique tubular core 63 having enlarged-diameter upper and lower end pieces 64 and 65. The core 63 and its end pieces 64 and 65 are disposed in a complementary inwardly-opening recess in ~he internal wall of the tubular sub 32 and securely mounted therein.
Although electrical insulation is not required, it is preferred to secure the core pieces 63-65 in the sub 32 by means such as a non-conductive potting compound.
As depicted in FIGURES 2B snd 2C, the lower portion of the tool body 38 is comprised of a tubular housing 66 which is cooperatiYely arran8cd for sealingly enclosing the electronic circuitry of the wireline ~ool 36 as well as for dependently supporting a reduced-diameter rod or axial member 67 on whlch the inner coil assembly 35 is coopera~iYely mounted. It should be noted that becau~e of the unique electromagnetic characteristics ~93Z5~ti of the coupling means 10, the support member 67 may be formed of steel or any material considered to have sufficient strength to withstand severe impact force~ as the running tool 36 i~ lowered into a well bore such 2S the cased well bore 15. A suitable nose piece 68 is arranged on the lower end of the support rod 67 so as to serve as a guide for the tool 36.
In the preferred embodiment of the inner coil assembly 35, a multi-turn winding 69 of a suitable conductor or insulated wire is wound in one or more layers of uniform diameter around the mid-portion of an elongated, thick-walled tubular core member 70 that i9 coaxially di5posed around the reduced-diameter support member 67 and secured thereon between upper and lower end pieces 71 and 72. A tubular shield 73 of a non-magnetic material such as sn electrically non-conductive reinforced pla~tic is coaxially disposed around the inner coil assembly 35 snd suitsbly arranged for physically protecting the coil. Although thls shield 73 must be formed of a non-magnetic materiAl, it can also be fabricated from an electrically-conductive metal sueh as aluminum, stainless steel or brass that is preerablg arran8ed in a fashion a9 to not short circuit the inductive coupling between the coil assemblies 31 and 35. Those skilled in the art will also appreciate that if the shield 73 i9 made of metal, a plurality of circumferentially-spaoed longitudinal slitq should be arranged ~round the Qhield to at least reduce, if not prevent, power lossei from unwanted eddy currentsO
It is of particular significance to note ~hat with the coupling means 10 of the present invention it is not essential to ~33~6 position the inner coil a~sembly 35 in close radial proximit~ to the outer coil assemblg 31 as would otherwise be the ca~e with a prior art inductive-coupling device such as any of those de~ices discussed above. Instead, those skilled in the art will realize from FIGURE 2C that the annular clearance Qpace between the two coil as3emblie3 31 and 35 i9 cignificantl~ greater than would be considered feaqible for efficiently transferring electrical energy between prior-art coil assemblies using conventional core material~. To achieve efficient energy transfer with substantial clearances between two coil aYsemblies as at 31 and 35, it has been found that a significant increase in the elec~romagnetic inductive coupllng between the coil assemblles i~q attained by forming inner and outer cores, 3uch as qhown at 63 and 70, of typical ferrite materials ha~ing a curie temperature point that i~ at leaqt equal to or, preferably, ~omewhat 8reater than the anticipated maximum subsurface or well bore temperature at which the coupling means lO~will be e~pected to operate.
In marked contrast to the core materisls typically used heretofore for prior-art inductive coupling~ such a8 described in U.S. Patent No. 3,209,323, the ferrite core materials u~ed in the practice of the invention have a high DC bulk re~i~tiYity, a Yery low magnetic remnance and a moderate magnetic perme~bility. It wlll, of course, be apprec~ated by those ~killed in the art tha~
ferrites are ceramic msgnetic materials that are formed of ionic cr~3tal~ having the genersl chemical composition ~Me)Fe2~3, where (Me) represent~ any one of a number of metal ions selected from a group con3isting of manganese, nickel, zinc,- mAgnesium, cadmium ~LZ93~9~i cobalt and copper. Examples of typical ferrites considered to be suitable for the coupling means 10 to be effective for use in commercial downhole service are those formed from one or more of the first three of those ions and ha~ing a bulk resistivit~
8reater than 10,000 ohm-meters.
One ferrite material which has been used to fabricate a preferred embodiment of the outer and inner coil assemblies 31 and 35 of the present $nvention is composed of eighteen percent zinc oxide, thirty two percen~ nickel oxide and fifty percent iron oxide which wa3 prepared Rnd conYerted iQ accordance with well-known proces3eq into that par~icular ferrite by controlled high temperatures to form a polycrystaline structure resembling spinel and in which the transitional metal ions are Qeparated by oxygen ions. The magnetic permeability of this ferrite material is approximately one hundred to two hundred times greater than the permeability of free space and it~ DC bulk resisti~ity is in exce~s of one million ohm-meterq. This preferred material also has a particularly low ~agnetic remnance. Since this particular ferrite has a curie temperature in excess of 250-degrees Celsius ti~e., 480-degrees Fahrenheit), it will be appreciated that these respective performance characteristics will be exhibited at any well bore temperature up to that temperature. It has been found that with thls ~nd other similar ferrites, the new and improved coupling means 10 o4 the invention will operate efficiently and with stability over a wide frequency band extendin~ from only a few Hertz eo several Megshertz.
It should be noted that where ferrites such RS the one .

~Z~3Z9~;

described above further include up to about ten percent zirconia in a crystalline or uncrystalline form, the toughneQs, mechanical strength and corrosion re~istance of the material will be greatly improved without affecting the electrical or magnetic properties of the ferrite material. Thu3~ where there iq a pos3ibility that the new and improved coupling means lO of the inYention might be subjected to substantial Yibrational or impact forces, ferrite~
including zirconia .qhould be consldered at least for the outer coil a3sembly as at 31. For instance, a typical situation where such ferrites might be conqidered is where the new and improved coupling mean~ 10 is to be emplo~ed ~o ~ransfer electrical power and/or data between surface equipment and one or more downhole senqors, recorders or measuring de~ice~ in a drill strlng which will be temporarily hfllted from time to time to enable a cable-lS suspended device such as the running tool 36 to be moved throughthe drill string to the downhole device.
Turning now to FIGURE 3, a schematic diagram is sho~n of typical electronic circuitry which may be used in con~unction with the new and improved coupling means lO of the lnYention for interconnecting the downhole tool ll to the surface equipment 12.
A~ depic~ed, the surface equipment 12 include~ a typical computer 74 which is coupled to the surface ends of the conductors 75 and 76 in the suspension csble 13 by way of a typical AC/DC ~eparator and combiner 77. As is typical, a signal driver 78 19 coupled between the computer 74 ~nd the combiner 77 and i8 cooperatively arranged for ~electiYel~ transmitting signal3 from the surface equipment 12 to ehe downhole tool ll. In a ~imilar fashion, a 9~

signal detector 79 is arranged between the computer 74 and the combiner 77 for receiving signals from the subsurface equipment 11 and cooperatively converting those signals into appropriate in~ut signals for the computer. The surface equipment 12 alco may include a power supply 80 that, for example, would be capable of supplying power to the sub-surface equipment for firing the perforating gun 22 as well as for operating any other device in the equipment ll.
As previously described by reference to FIGURE 2C, the downhole ruflning tool 36 is depend0ntly suspended from the cable 13 and the inner coil assembly 35 in the tool is cooperatively connected to the conductors 75 and 76 in the suQpension cable.
In the preferred embodiment of the running tool 36, the cable conductors 75 and 76 are connected to the coil a~sembly 35 by a wireline receiver/driver snd a DC/DC con~erter in an enclosed cartridge 90 which are cooperatively arranged for providing a ~uitable interface between the Yu~pension cable 13 and the coil winding 69. In the illustrated embodiment of the sub-qurface .
equipment 11, the outer coil assembl~ 31 i3 cooperatively coupled to the downhole me~surement means 24 by A typical frequency-shift keying demodulAtor 81 and a synchronous pul~e driver 82 that sre in turn coupled to a typical microprocessor or computer 83 b~ way of a univer al as~nchronous receiver-transmitter 84. To qupply power from the surface equipment 12 to one or more devices in the ~ub-surface equipment 11, a rec~ifier 85 is connected acro~s the winding 62 of the outer coil assembly 31 and operativel~ arranged to be driven when it i3 desired to supply power eo those devices.

~Z~

As previously mentioned, the self-contained battery 29 may also be appropri~tely arranged for supplying power to one or more of the component~ of the downhole equipment 11. Since it may also be desired to recharge the battery 29 while it is still downhole, the rectifier 85 is also preferably arranged to be utilized for recharging the battery.
Those skilled in ~he art will, of course, appreciate that the tubing-conveyed perfora~ing gun 22 may be actuated in various ways. For instance, as described in more dctail ln the aforementioned U.S. Patent No. 4,509,604, the perforating gun 22 may be selectively fired b7 ~arying the pressure of the fluids in the upper portion of the cased well bore 15 above the packer 20.
There are also other firing systems employing A so-called l'drop bar" that is introduced into the surface end of the supporting pipe string with the expectation being that the falling bar will strike an impact-responsive detonator with sufficient force to actuate a perforating gun ~uch a9 the gun 22. Other systems that have been proposed involve an inductive coupling which, as fully described in U.S. Patent No. 4,544,035, is arranged on the lower end of a well bore cable for coupling a surface power source to the perforating gun. There have also been proposals to combine two or more firing 8yqtem9 90 as to have an alternative firing system when possible.
Accordingl~, it will be appreciated tha~ the new and improved coupling means 10 of the pre~ent invention are uniquely arranged to provide an alternative~firin~ 3y~tem ~hould the gun ; 22 fail eo fire in responqe to varying the presYure in the cased : 24 ~93~

well bore 15 as described in U.S. Patent No. 4,509,604. As shown in FIGURE 3, a typical driver 86 may be coupled to the downhole computer 83 and cooperatively arranged to selectively control a typical relay 87 coupling an electrically-respon~ive detonator 88 5 to the winding 62 of the outer coil assembly 31. In this manner, when the computer 74 at the surface iq operated to ~end a proper command signal to the downhole computer 83, the relay 87 will be closed so B5 to couple the detonator 88 to the power supply 80 at the surfacec The surface power supply 80 i9, of course, operated a~ needed to fire the gun 22.
To illustrate the operation of the circuitry depicted in FIGURE 3, FIGURE 4 showq a representative pulsating DC voltage waveform a9 would commonly appear across the winding 62 of the outer coil assembly 31 during normal operation of the new and improved coupling mesns 10 of the present invention. In keeping with the previous description of the downhole circuitry depicted in FIGURE 3, DC power from the power supply 80 is transmitted by way of the cable 13 to the electronic cartridge 90 where typical switching power supply circuitry functlons for converting the DC
power into a pulsatlng DC voltage that will be supplied to the downhole electronic clrcuitry in the ~ub-surface equipment 11 by way of the inducti~e coupling between the coll asse~blies 31 and 35 of the ne~ and l~proved coupling mean~ 10. The rectifier 85, of course, func~ions to convert the pulsa~ing DC vol~age that is tr~nsferred across the coil as~emblies 31 and 35 to the voltage required by the equipment 11.
It will, of course, be unders~ood by those skilled in ~Z~3~6 the art that data communication between the ~ub-surface equipment 11 and the surface equipment 12 can be carried out in any one of ~arious manner~. Neverthele~s, with thé preferred embodiment of the electronic circuitr~ shown in FIGURE 3, communication between the Qub-surface equipment 11 and the surface equip~ent 12 emplogs a typical syqtem of bipolar modulation which is half duplex by nature. As schematically represented in FIGURE 4, the wireline receiver/driver and DC/DC converter in the enclosed cartridge 90 are cooperativel~ arranged to normally produce a typical qquare-wave output wavefor~ across the winding 62. Data communication between the circuitry in the cartridge 90 and the circuitry in the sub-surface equipment 11 i9 carried out by way of typical requency-shift keying techniques or so-called 'IFS~" modulation of the DC waveform. Data communication in the opposite direction between the electronlc circuitry in the sub-~urface equipment 11 and the cartridge 90 is preferably carried out by using typical synchronous impedance modulation of the DC waveform. With thi~
technique, the drlver 82 i9 selectively operated for applying ~ignificant impedance ch~nges across the winding 62 of the outer coil assembly 31. For example, a~ seen in FIGURE 4, to signal one binar~ bit, the driver 82 is operated to create a momentary ~hort circuit across the winding 62 during a positive-going half cycle 91 of the waYeform. This momentary short circuit will, of course, temporaril~ reduce or cut off the voltage acros~ the winding 62 for a predetermined period of time 99 depicted by the voltage excursions ~hown at 92 and 93. In a similar fashion, the opposite binar~ bit ls represented by operating the driver 82 to ~Z~?32~6 momentarily reduce the voltage across the winding 62 during a negative-going half cycle of the DC waveform for a predetermined period as depicted by the voltage excursions shown at 95 and 96.
The operaeing frequency for the illustrated circuitry is between twenty to one hundred Kilohertz. A typical period for operating the dri~er 82 to produce the depicted roltage excursions aq, for example, between the excursions 92 and 93 is approximately twenty to thirty percent of the time for a half cycle.
It will, of course, be recognized that the power supply 80 in the surface equipmènt 12 can be arranged to al~o pro~ide a source of AC ~oltage. Accordingly, the new and improYed coupling means lO can al90 be adapted for efficiently transferring power between the surface equipment 12 and the perforating gun 22. To carry this out, the power supply 80 is arranged to operate in a frequency range between one hundred to one thousand ~ilohertz snd provide an output voltage of up to eight hundred volts RMS with an output current of at least one ampere. Thus, b~ chooqing an output frequency th~ is optimized in relation to the particulsr suspension cable as at 13 being used for a perforating operation, there will be an efficient tran~fer of electrical energy between the power supply 80 and the detonator 88. Thi~ optimum frequenc~
is quch that the effecti~e input impedance of the coil 69 will be approximatel~ equal to the mathemaeical complex conjugate of the charactaristic impedance of the quspension cable as st 13. It should, of cour~e, be recognized that since the new and improved : coupling meanQ lO exhibits low los~es an~ stable characteristics oYer a wide fraquency range, the optimization of frequency can be 2~

~93Z96 utilized for optimizing the transfer of electrical power acros3 the new and improYed coupling means 10 for a wide variety of well bore cables such ~3 typical armored ~ingle~conductor cables or so-called "monocable~" or typical multi-conductor cables. It will, therefore, be appreciated that this optimized transfer of electrical energy can also be achieved wholly independentl~ of the electronic circuity shown in FIGURE 3 where there is no need to transmit data between the surface and the downhole equipment.
Thus, should the downhole equipment consist only of a perforating gun9 the detonator (as at 88) can be connected directly across the winding 62 of the outer coil assembly 31 without any other downhole electrical or electronic componentq being required.
It will also be recognized by those skilled in the art that the new and improYed coupling me~n~ 10 do not obstruct the axial flow passage 27 through the entire length of the downhole tool 11. Once the perforstor 22 is actuated to establish fluid communication between the earth formation 17 and the cased well bore 15 below the packer 20, connate fluids can flow easlly into the isolated portion of the well bore and pass directly through the flow pas~age 27 to the tubing strlng 16. When the running tool 36 ls lower~d through the tubing ~tring 16 and move~ into the tubular body 32, the collet flnger~ 45 and the 1ug9 46 will function as previously described to enter the recess 39. Then, once tension is applied to the ~uQpension cable 13, the body 38 will be pulled upwardl~ in ralation to the sleeYes 43 and 4~ to allow the enlarged-diameter bod~ portion 52 to move behind the collet fingers 45. A~ preYiously described, this will lock the ~Z93;~:gf~

running tool 36 in the tubular member 32. It will be recognized that once the tool 36 i5 locked into position, fluid flow will be diver~ed around the tool by way of one or more bypas~ ports 89 in the lower end of the tubular member 32 which thereby communicates the axial bore 27 in the bod~ 25 with the annular bypaas passage 34 defined around the tubular member 32~
It will be appreciated that the running tool 36 m~y be used in various ways. For in~tance, the running tool 36 may be positioned in the tubular member 32 and the ~urface computer 74 operated as required for connecting one or more of the several senQors 28 with the surface computer for obtaining a Qeries of reAl-time meaaurements of the output aignal~ provided by these ~ensors. Communication between the downhole equipment 11 and the surface equipment 12 will, of course, be carried out in keeping with the previous deccriptions of FIGURES 3 and 4. In a similar fashion, the wireline running tool 36 may be positioned from time to time in the tubulsr member 32 and the ~urface computer 74 operated for couplln~ the downhole recorder 30 with the surface computer. Thereafter, the surface computer 74 may be operated as required to interrogate the downhole recorder 30 and utilize the abo~e-described communic~tion techn~ques for tranQferring data that has been preYiou~17 ~tored on the downhole recorder to the memor~ of the surface computer while the running tool 36 was not positioned in the dow~hole equipment ll. It ~hould be recalled 25 89 well that the wireline tool 36 may be utilized as ~eeded for recharg1ng the downhole battery ~9 as well as for operating the perforating gun 22. Accordingly~ it will be appreciated ~hat the 3~93~9~
presen~ inYention has provided new and improved apparatus for conducting various te~ting and completion operations including unique coupling means adapted to be coupled to the lower end of a typical well bore suspension cable for transferring electrical data and/or power between the surface and downhole apparatus in a well bore.
; ~hile only one particular embodiment of the in~ention has been shown and described herein, it i9 apparent that change.q : and modificationc may be made thereto without departing from this invention in its broader a3pects; and, therefore, the a m in the appended claims i9 to cover all ~uch changes and modifications a~
ma~ fall within the trne spirit and scope of this invention.

THE E~BODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Well bore apparatus comprising:
a sub-surface tool including a selectively-operable means which includes at least one electrical device;
coupling means including inner and outer telescopically-interfit~ing coil assemblies, said coil assemblies further including, inner and outer cores formed substantially of ferrite materials having a DC bulk resistivity greater than ~en thousand ohm-meters and cooperatively arranged so tha~ said coil assemblies can be telescopically interfitted together, said ferrite material being selected from the group of metal ions consisting of manganese, nickel, zinc, magnesium, cadmium, cobalt, and copper and having a curie temperature polnt greater than the maximum anticipated well bore temperature ~o whlch said coil assemblies will be exposed, said ferri.te materials further includiny an additive of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer cores, respectlvely wound around said inner and outer cores and electromagnetically intercoupled to one another whenever said coil assemblies are telescopically interfitted together, means on said tool for retaininy one of said coll assem~lies in a posi~ion in a well bore where it can be telescopically interfitted with the other of said coil assemblies, and means for . ~ .

~Z~3~

conneeting said coil of said one coil assembly to said electrical device; and means on said other coil assembly for connecting its said coil to the conductors in a suspension cable supporting said other coil assembly for movement in a well bore to said position where said coil asse~blies are ~elescopically interfitted.

2. The well bore apparatus of claim 1 wherein said coil assembly is said outer coil assembly.

3. The well bore apparatus of claim 1 wherein said electrical device is an electrically-actuated detonator.

4. The well bore apparatus of claim 1 wherein said electrical device is a rechargeahle battery.

5. The well bore apparatus of claim 1 wherein said electrical devlce is an electrical ~ensor.

6. The well bore apparatus of claim 1 wherein said electrical device is an electrically-responsive relay.

7. The well bore apparatus of claim 1 wherein said electrical device is a computer.

. .

~93ZS~;
. 70261-54

8. The well bore apparatus of claim 1 wherein said electrical device is a data recorder.

9. The apparatus of claim 1 wherein said ferrite materials are selected from the group consisting of magnesium ferrite, nickel-zinc ferri~e, iron oxide magneti~e and nickel ferrite and having a curie temperature point greater than the maximum anticipated well bore temperatures to which said coil assemblies will be exposed.

10. The apparatus of claim 1 wherein at least one of said cores is formed of a ferrite composed of about eighteen percent zina oxide, thirty two percent nickel oxide and fifty percent iron oxide.

11. Well bore apparatus comprlsing~
sub-surface equipment including a tubular body adapted to be coupled into a pipe string and positioned in a well bore;
selectively-operable means on said body including at least one electrical device;
coupling means including inner and outer telescopically-interfitting coil assemblies, said coil assemblies further including, inner and outer core members respectlvely formed substantially of ferrite ma~erials having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively sized and ~L293~

arranged so that sai~ coil assemblies can be telescopically interfitted together, said ferrite materials being selected from the group of metal ions consisting of manganese, nickel, zinc, magnesium, cadm.ium, cobalt and copper and having a curie temperature point greater than the anticipated maximum well bore temperatures to which said coil assemblies will be exposed, said ferrite materials further including an additive of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer core members, respectively wound around said inner and outer core members and electromagnetically intercoupled t~o one another whenever said coil assemblies are telescopically interfitted together, means for coaxially mountiny said outer coil assembly within said body and in posi~ion to telescopically receive said inner coil assembly, and means for connecting said outer co.ll to said electrical device;
means on said inner coil assembly for connectiny said inner coil to the conductors in a suspension cable dependently supporting said inner coil assembly for movemen~ through a pipe string in a well bore to a position therein where said inner and outer coil assemblies are telescopically interfitted; and surface equipment connected to the conductors in a suspension cable supporting said inner coil assembly.

:~Z93Z9f~

12. The well bore apparatus of claim 11 wherein said surface equipment is adapted to be selectively operated for transferring electrical energy ~hrough a suspension cable supporting said inner coil assembly when said inner coil assembly is positioned wi~hin said outer coil assembly.

13. The well bore apparatus of claim 11 wherein said surface equipment is adapted to be selectively operated for receiving electrical energy being sent from said electrical device through a suspension cable suppor~ing said inner coil assembly when said inner coil assembly is positioned within said outer coil assembly.

14. The well bore apparatus of claim 11 wherein said surface equipment is adapted to be selectively operated for transmitting electrical energy beiny sent to said electrical device through a suspension cable supporting sald inner coil assembly when said inner coil assembly is positioned within sald outer coil assembly.

15. The well bore apparatus of claim 11 further including means cooperatlvely arranged ~or releasably securing said inner coil assembly in its said position within said body where said inner and ou~er coil assemblies are telescopically interfitted.

16. The well borP apparatus o~ claim 11 further including means cooperatively arranged on said body for providing a fluid bypass passage around said inner aoil assembly when it is in its .

, l~g32~36 said position within said body.

17. The well bore apparatus of claim 11 further including packer means cooperatively arranyed on said body and adapted to be set in a well bore for isolating an interval thereof below said body.

18. The well bore apparatus of claim 17 wherein said electrical device is an electrical sensor cooperatively arranged on said body for measuring at least one characteristic of the ~luids in such an isolated well bore interval.

19. The well bore apparatus of claim 17 wherein said electrical device is a data recorder; and said well bore apparatus further includes at least one electrical sensor cooperatively arranged on said body for measurlng at least one characteristic of the fluids in such an isolated well bore interval and operatively coupled to said data recorder for storing data representative of such fluid characteristics.

20. The well bore apparatus of claim 19 wherein said well bore apparatus further includes a rechargeable battery cooperatively arranged for supplying power to said data recorder and electrical sensor, and means cooperatively arranged for int~rconnecting said outer coil assembly to said battery when said battery is to be recharged by transmitt~ng power from said surface ~z~3~9~ 70~61~54 equipment.

21. The well bore apparatus of claim 17 whereln said electrical device is a computer; and said well bore apparatus further includes a plurality of electrical sensors cooperatively arranged on said hody adapted for measuring selected characteristics of the flu.ids in such an isolated well bore interval respectively coupled to said computer and adapted for being selectively interrogated thereby when signals representative of such fluid characteristics are to be fed to said computer.

22. The well boxe apparatus of claim 17 wherein said electrical device is an electrically-actuated detonator; and said well bore apparatus further lncludes a perforating gun dependently coupled to said body and adapted to be actuated by said detonator.

23. The apparatus of claim 19 wherein at least one of said cores is formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

24. Apparatus adapted to be disposed in a well bore for lnductively coupling power and data signals between surface equipment and sub surface equipment, comprising:

a first conductor adapted to be connected to the surface equipment;

.~ 37 ~93~

a second conductor adapted to be connected to the sub-surface equipment; and coupling means interconnecting said first conductor to said second conductor for conducting sai~ power and data signal between said surface equipment and said sub-surface equipment, said coupling means including, a first coil connected to said first conductor, a second coil connected to said second conductor and coaxially disposed around said first coil, said second coil being inductively coupled with said first coil, and core means disposed within and around said first coil and said second coil for assisting in the inductive coupling of said first coil and said second coil, said core means comprising a speclfic ferrite material, said specific ferrite material of said core means including ceramic magnetic materials formed of ionic crystals and havlng the general chemical composition (Me)Fe203, where (Me) is a metal ion selected from a group consistin~ of manganese, nick~l and zinc.

25. The apparatus of claim 24, wherein said specific ferrite material has a curie temperature point that is equal to or grea~er than an anticipated maximum subsurface temperature within said well ~ore.

2&. The apparatus of claim 25 wherein said specific ~errite material has a high DC bulk resisti~ity, a low magnetic remnance, 3%

~Z~3;~:~6 and a moderate magnetic permeahllity.

27. The apparatus of claim 24, wherein the bulk resistivity of the (Me) metal ion is greater than 10,000 ohm-meters.

28. Apparatus adapted for elec~romagnetically coupling electrical conduc~ors in a well bore suspension cable to well bore apparatus having at least one electrical device and comprising:
inner and outer coil assemblies respectively including, inner and outer core members formed substantially of ferrite materials having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively arranged so that said inner coil assembly can be telescopically disposed withln said outer coil assembly, said core members being formed of ferrites selected from the group of metal ions consisting of manganese, nickel, zinc, magnesium, cadmium, cobalt and copper, said ferrites further including an additive of up to about ten percent by weight of zirconia, and inner and outer coils disposed within said inner and outer core membexs, respectively wound around said inner core member and inductively coupl~ng the conductors in a suspension cable connected to one of said coils to a well bore electrical device connected to the other of said coils whenever said inner coil assembly is disposed within said outer coil assembly.

29. The apparatus of claim 28 wherein said other coil is said outer coil.

~2~3;~6 30. The apparatus of claim 28 wherein said core members are formed of ferrites selected from the group consisting of nickel-zinc ferrite, iron oxicle magnetite, nickel ferrite and magnesium Eerrite and respectively having a curie temperature point that is at least equal to the maximum anticipated well bore temperatures to which said coil assemblies will be exposed.

31. The apparatus of claim 30 wherein said inner and outer core members are respectively formed of the same ferrite material.

32. The apparatus of claim 28 wherein at least one of said core members is formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

33. The apparatus of clalm 28 wherein said inner and outer core members are respectively formed of a ~errite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

34. Apparatus adapted for electromagnetically coupling electrical conductors in a well bore suspension cable to well bore apparatus having at least one electrical clevice and comprising:
inner and outer coil assemblies respectively including, inner and outer core members formed substantially of ferrite materials having a DC bulk resistivity greater than ten thousand ohm-meters

Claims

and cooperatively arranged so that said inner coil assembly can be telescopically disposed within said outer coil assembly, said core members being formed of ferrites selected from the group of metal ions consisting of manganese, nickel, zinc, magnesium, cadmium, cobalt and copper respectively having a curie temperature point that is at least equal to the maximum anticipated well bore temperatures to which said coil assemblies will be exposed, said ferrites further including an additive to the ferrite material of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer core members, respectively wound around said inner core member and inductively coupling the conductors in a suspension cable connected to one of said coils to a well bore electrical device connected to the other of said coils whenever said inner coil assembly is disposed within said outer coil assembly.

35. The apparatus of claim 34 wherein said other coil is said outer coil.

36. The apparatus of claim 34 wherein said core members are formed of ferrites selected from the group consisting of nickel-zinc ferrite, iron oxide magnetite, nickel ferrite and magnesium ferrite and respectively having a curie temperature point that is at least equal to the maximum anticipated well bore temperatures to which said coil assemblies will be exposed.

37. The apparatus of claim 36 wherein said inner and outer core members are respectively formed of the same ferrite material.

38. The apparatus of claim 34 wherein at least one of said core members is formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

39. The apparatus of claim 34 wherein said inner and outer core members are respectively formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

40. Apparatus adapted for electromagnetically coupling electrical conductors in a well bore suspension cable to well bore apparatus having at least one electrical device and comprising, inner and outer coil assemblies respectively including, inner and outer core members formed substantially of ferrite material having a DC bulk resistivity greater than ten thousand ohm-meters and cooperatively arranged so that said inner core assembly can be telescopically disposed within said outer coil assembly, said core members being formed of ferrites selected from the group consisting of nickel-zinc ferrite, iron oxide magnetite, nickel ferrite and magnesium ferrite and respectively having a curie temperature point that is at least equal to the maximum anticipated well bore temperatures to which said coil assemblies will be exposed, said ferrites further including an additive to the ferrite material of no more than about ten percent by weight of zirconia in a crystalline or uncrystalline form, and inner and outer coils, disposed within said inner and outer core members, respectively wound around said inner core member and inductively coupling the conductors in a suspension cable connected to one of said coils to a well bore electrical device connected to the other of said coils whenever said inner coil assembly is disposed within said outer coil assembly.

41. The apparatus of claim 40 wherein said other coil is said outer coil.

42. The apparatus of claim 40 wherein said inner and outer core members are respectively formed of the same ferrite material.

43. The apparatus of claim 40 wherein at least one of said core members is formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.

44. The apparatus of claim 40 wherein said inner and outer core members are respectively formed of a ferrite composed of about eighteen percent zinc oxide, thirty two percent nickel oxide and fifty percent iron oxide.