CA1074292A

CA1074292A - Method and apparatus for telemetering information from a borehole to the surface

Info

Publication number: CA1074292A
Application number: CA293,620A
Authority: CA
Inventors: Early B. Denison
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1976-12-23
Filing date: 1977-12-21
Publication date: 1980-03-25
Also published as: NO149325B; DE2757085A1; ATA919377A; NO774396L; AU509714B2; GB1558300A; AU3183277A; NO149325C; DE2757085C2; AT353731B; US4126848A; BR7708497A; FR2375433B1; FR2375433A1

Abstract

A B S T R A C T
A method and apparatus for telemetering information from a borehole to the surface with drilling, wherein a tensioned wireline comprising an electric conductor is used to transit the information form a low level in the borehole to an in-termediate position in the drill string, and a plurality of drill pipe sections, each comprising an insulated electrical conductor, is used to transmit the information from the intermediate position to the surface. The tensioned wireline may be removed form the surface without removing the drill string from the borehole.

Description

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The invention relates to telemetering systems designed to transmit information from a borehole to the surface while drilling a well. In the rotary drilling method, a string of pipe, having a drill bit at its lower end, is rotated to drill the well while circulating fluid down the drill pipe and up through the annular space between the drill pipe and the borehole. The circulating fluid is used to carry the drill bit cuttings to the surface and clean out the borehole. While the most common type of rotary drilling uses a drill rig to rotate the drill string, the invention may also be used when a mud turbine is used to rotate the drill bit.
One of the prior art systems used to telemeter in-formation while drilling relies upon the production of pressure pulses in the mud stream to telemeter inform-ation to the surface. Other systems, relying upon in-troduction of a wireline comprising an electric con-ductor from the surface to the bottom of the borehole, have been used to transmit informatio~ to the surface.
Still other systems use a drill string comprising a plurality of drill pipe sections interconnected in end-to-end relationship and having an electric circuit passing through the sections. This circuit partly consists of a length of wireline comprising a conductor and spanning a portion of the drill string, and of a plurality of electrically coupled insulated conductors, each of said ~.~

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latter conductors being positioned in a drill pipe section and being coupled to suitable ring-like electrical connectors disposed in the sealing shoulders of each such section. This latter system permits deepening the borehole while adding additional sections of such latter drill pipe sections and still maintaining an electrical circuit to the bottom of the well. The advantage of using a wireline to span a portion of the drill string is a reduced cost since less of the said latter pipe sections are required. This latter system relies on conventional wireline equipment for install-ing the wireline spanning a portion of the drill string.
Ob;ect of the invention is a specialized technique which allows an easy installation as well as an easy removal of the wireline.
The invention provides a method for drilling a borehole and simultaneously passing electric signals between a level in the borehble and the surface, said method includ-ing the steps of: lowering a portion of a drill string into the borehole, said portion comprising a plurality of inter-connected drill pipe sections; lowering through the interior of said portion of the drill string a wireline comprising an insulated electrical conductor adapted for transmitting electric signals, said conductor being provided at both ends thereof with an electrical connector; releasably coupling the lower electrical connector of the conductor with an electrical connector arranged in the interior of the drill string, and releasably anchoring the lower end of the wireline to the drill string; releasably anchoring the upper end of the wireline to the top of said portion of the drill string near the upper end thereof, such that the wireline is maintained under tension, and that the upper electrical connector there-of is arranged for transmission of signals between this upper '-'.F~ :
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connector and electrical coupling means carried by the upper end of the upper drill pipe section of the said portion of drill string; adding drill pipe sections to the portion of drill string present in the hole, whilst lowering the drill string in the hole, each of said sections containing an insulated electrical conductor electrically connected at each end of the section to an electrical coupling means arranged to cooperate with the electrical coupling means of adjacent sections for transmission of signals between the coupling means; and transmitting electric signals along the conductors, connectors and coupling means.
The invention also provides an apparatus for telemetering information from an instrument package in an instrument sub si~uated in a borehole while drilling the borehole, using a drill string comprising said instru-ment sub and carrying a drill bit, said apparatus compris-ing: a wireline containing at least one electrical conductor, ~07~2~t~
said wireline extending through the interior of a lower portion of the drill string; a downhole electrical connector arranged in the interior of said portion of the drill string and secured thereto; an electrical connector electrically coupled to the lower end of the conductor in said wireline, and adapted to releasably engage the downhole electrical connector for transmission of signals; anchoring means for removably securing the lower end of the wireline to the portion of the drill string such that the wireline can be axially tensioned; anchoring means for removably securing the upper end of the wireline to the portion of the drill string such that the wireline is axially tensioned; a plurality of interconnected drill pipe sections forming the other, upper portion of the drill s~ring, each pipe section having an insulated electrical conductor extending therethrough and being electrically connected at both ends thereof to electrical coupling means that are arranged for the transmission of signals between the coupling means and the electrical coupling means of adjacent pipe sections;
and electrical coupling means electrically connected to the upper end of the conductor in said wireline and arranged for the transmission of signals between this coupling means and the electrical coupling means of the lowermost of said plurality of pipe sections.

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~ The present invention will be described by way of example in more detail with reference to some em-bodiments thereof shown in the drawings.
Figure 1 shows a longitudinal section over a drill string with a wireline installed therein;
Figure 2 is a side view of a complete drill string, Figure 3 is an enlarged view of the sub member used for the downhole anchoring of the wireline;
Figure 4 is an enlarged view of the means for uphole anchoring of the wireline;
Figures 5a and 5b are vertical sections of the releasable downhole means for anchoring the wireline;
and I Figure 6 is a vertical section of an alternate downhole means for anchoring the wireline.
Figures 1 and 2 show a drill string having a wire-line installed in the bottom portion, and utilizing in the upper portion ~ereof pipe sections having a con-ductor arranged in each section (such as those described in U.S. patent specification No. 3,696,332). In particular, Figure 1 illustrates a drill string which comprises a lower part 10 and an upper part 16 separated by the uphole anchoring sub 23. The lower part 10 may comprise drill collars for weighting the drill bit during rotary drilling operations. The upper part 16 of the drill string has provisions for a slip ring Z

arrangement 17 at its top. The slip rings are connected to the uphole electronics which are indicated as a receiver 18. The instrument package, or sub, is illustrated as 11 and may comprise various measuring devices. For example, devices may be utilized that detect the inflow of gas or other fluids into the well, as described in U.S. Patent No. 3,776,032.
Similarly, devices for measuring the resistivity of the formation, or the inclination and azimuth of the borehole may be included. The instrument sub is provided with conventional box and pin ends that may be connected to drill bit 19 at one end and the downhole anchoring sub 12 at the other. The anchoring sub 12 is provided with box and pin ends connected to the lowermost drill collar and the instrument sub, respectively. The sealing sho~lders of the instrument sub 11, and the anchoring sub 12, are provided with circular electrical contacts in the sealing faces of the screw thread connections.
. Electrical connection to the anchoring sub 12 is made by means of the releasable downhole anchoring means 13 that is provided with a series of sinker bars 14 on its top.
As will be explained below, the sinker bars are re-quired to provide the weight required to operate the release mechanism of the connector. The sinker bars are connected to the wireline 15, which is provided with additional spacing members 21 at its top. The spacing )7~2~ ~
members 21 may be specially-designed sinker bars or short lengths of wireline which provide bo~h an electrical circuit between the wireline and the uphole connector, and means for adjusting ~e overall length of the wireline. The spacer bars 21 are coupled ~o the uphole anchoring means 22, which is positioned in the uphole anchoring sub 23. In addition, the uphole an-choring sub is provided with a box end that contains a ring-type electrical contact for electrically coupling to a ring-type electrical coupling in the sealing face of the pin-end of the drill pipe section that is to be screwed on top of the sub 23.
The wireline is preferably a flexible steel cable having a single electrical conductor covered by insulating material. This type of cable can easily be provided with thr~hded term~nals at its ends. The terminals provide a means for forming both a physical and electrical con-nection with adjacent members. The sinker bars 14 have a central electrical conductor and threaded ends that mate with the terminals on the wireline. Similar sinker bars may be used for the spacers 21, although short lengths of wireline may be preferred.
ln operation, a portion of the drill string carrying the instrument and lower anchoring subs 11 and 12, as well as the bit ~9 at the lower end and having the up-hole anchoring sub 23 installed at its upper end, is - 9 - :
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lowered into the borehole. The wireline is then made up with the downhole anchoring means 13, the downhole sinker - bars 14 and suitable spacers 21, as required. The wire-line can then be lowered into the portion of the drill string suspended in the hole, and the downhole anchoring means 13 latched on to the downhole anchoring sub 12.
- After the lower connection is made, the wireline can be tensioned by connecting the uphole anchoring means on the uphole anchoring sub 23. If the wireline 15 should prove too long to permit applying the proper tension, some of the spacing members 21 may be removed;
while if it is too short, additional ones can be installed. Thus, it is possible to tailor the length of the wireline 15 that will permit the application of the desired tension to anchor the uphole anchoring means 22 in pos ~ior.. Finall~, the electr;cal wire 2ll is plugged into the uphole anchoring sub 23. After this is completed, drill pipe sections forming the upper portion 16 of the drill string are added on the !~ ~
lower portion 10 thereof. Each of these pipe sections carries an insulated electrical conductor that is provided at the ends thereof with electrical coupling means. ~he electrical coupling means of adjacent sections are arranged in signal transmitting relation-ship. Such sections are known i.a. from the U.S. patent specification No. 3,696,332 (Shell Oil Company, filed ~ -10- ~ ~f~ 3 ~.
~ 25th May, 1970, issued 3rd October, 1972). After completion of the drill string (as shown in Figure 2), the well can be drilled while providing continuous telemetering of informat;on from the downhole to the surface. The wire-line 15 preferably bridges as much of the drill string that extends into the borehole as desired. Normally, sufficient drill pipe will be lowered into the bore-hole to extend from the surface to near the bottom, and the wireline used to span this complete length. Only the top portion of the drillstringwill comprise the pipe sections provided with insulated eleetrical con-ductors extending between two electrical coupling means per section.
Referring now to Figure 3, there is shown an en-larged vertical section of the downhole anchoring sub 12.
Th~ sub 12 is prcvidcd with a pin end 1l7 and a box end 46 so that it may be coupled directly into the drill eollars or drill strings, as required. In addition, the sealing shoulder of the pin end 47 is provided with an -annular groove 30 containing insulating material, in which a contaet ring 30A is installed. A passage 31 is formed in the sub so that the eontact ring 30A may be eoupled by means of a wire (not shown) to the male electrical connector 40 disposed co-axially in the housing 33. The housing 33 is formed from a generally eylindrical vertical member, whieh is disposed eo-axially .

^~ with the sub, and two arms 34 and 48 which project at right angles. The housing is mounted in the sub by bolts -37 and 43 that thread into the two arms 3LI and 48. The lower arm 34 is provided with a bore 36, which com-municates with passage 31 to permit a wire (not shown) to be installed to connect the contact ring 30A in annular groove 30 with the male electrical connector 40.
In addition, 0-ring 35 is positioned in the arm to seal between the arm and the sub, while a similar 0-ring 38 is used to seal between the bolt 37 and the outer surface of the sub. A vertical passageway 42 is provided in the vertical portion of the housing 33, so that the electrical wire (not shown) can be passed up and connected with the lower end 41 of the male connector 40. The downhole anchoring sub 12 is completed by protection collar, or fishing neck 44, having a sloping top surface 45 to assist the re-leasable connector in centering itself over the male connector. The male connector 40 may be one-half of an electrical connector made by Keystone Engineering Company of Houston, Texas and marketed under the trade name "Kemlon". "Kemlon" connectors are used in the petroleum industry for coupling conventional wirelines to tools whi_h are lcwered _nto the borehole for .-unning surveJ-s.
Referring now to Figure 4, there is shown the uphole anchoring sub 23 with uphole anchoring means 22 used to both anchor the upper end of the wireline 15 and provide ~ ~ -12- ~ ~7~
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an electrical connection between the conductor of the wireline and the drill pipe section of the upper portion 16 of the drill string (see ~igure 2). As shown at the bottom of Figure 4, the spacing member 21 threads into the bottom of the anchoring means 22. This provides a secure attachment between the upper end of the wireline and the anchoring means 22, so that a tension force can be applied to the anchoring means 22 to tension the wireline. The anchoring means 22 has a central member 81 that is provided with a central bore 80, so that an in-sulated electrical conductor (not shown) may be used ~or coupling the electrical conductor of the wireline to the lower half of the electrical connector 93. The central member 81 is attached to a plurality of radial webs 82 which serve to centre the central member in the cylindrical member 83. The cylindrical member 83 is in turn supported by webs 84 which join it to the outer cylindrical member 85 of connector housing. The t~' cylindrical member 83 may also be supported by a bolt arrangement, similar to that shown in Figure 3 for supporting the housing 33. The outer cylindrical member 85 rests on a Fhoulder 86, formed in the upper an-choring sub 23.
A plurality (for example two) pivoted fingers 90 is provided at the top of the central member 81. The fingers are provided at their lower end with a notched 7 4 ~ ~
- end 91 which engages the top edge 92 of the cylindrical member 83. The fingers are biassed towar~ a retracted or inward position by a plurality of flat leaf springs 94. Thus, when the central member 81 is lîfted, for example by attaching a suitable fishing tool (not shown) to the fishing neck 89, the radial fingers 90 will be retracted towards the member 81, and the member 81 can be lowered through the central bore of the cylindrical member 83. If desired, additional means may be used to positively force the fingers inwardly and reduce the possibility of the fingers being jammed in an extended position. The downward displacement of the member 81 is required to release the downhole an-choring means as will be described below. In a similar manner, the member 81 can be lifted to.tension the wireline and a setting tool (not shown) be used to move the fingers 90 outwards into place to anchor the housing 81 on the top of the member 83. The physical movement of the fingers will be relatively simple since the member is installed while the upper anchoring sub 23 is on the level with the drill rig floor. The upper half of the electrical connector 93 is coupled by a short cable 24 to ~ne half of the elect~ical connector 95~ A suitable passage 98 is formed in the wall of the member 23, so that an insulated electrical conductor (not shown) may be run from the second half of the electrical connector ..

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~ - 95 through a passage 96 to an electrical contact ring : 99 embedded in the insulating material 99A in the annular groove 99B. This provides a means by which the dri.ll pipe section of the upper part 16 of the drill string may be coupled directly to the upper anchoring sub 23 and electrical contact may be established between the electrical coupling means disposed in the sealing shoulders of the adjacent members.
Referring now to Figures 5a and 5b, there is shown an enlarged longitudinal section of the downhole anchoring means 13 of Figure 1. The downhole anchoring means is a modified wireline overshot tool manufactured by Taylor Made Oil Tools Company of 4430, Steffani Lane, Houston, Texas. The tool has been modified to permit a single electrical conductor to pass down the centre with a female electrical connector 67 at the lower end that connects with the male electrical connector 40 of the downhole anchoring sub (see Figure 3). The downhole an-choring means comprises an outer housing 49 consisting of a plurality of parts that are interconnected by screw : threads as shown in the drawing. The housing 49 is provided with an internally-threaded upper end 50 into which the sinl~er bars 14 (s~e ~igure 1) r..ay ~e threaded to attach the wireline cable 15 to the downhole an-choring means 13. An electrical contact point 51 is biassed upwardly by means of a spring 52 positioned in an insulated 1~

-- housing 60, and held in position by an insulated washer 57 and a snap ring 57A. The spring 52 also provides an electrical connection between the contact 51 and the flathead screw 53. The flathead screw 53 threads into the top of the tubular conductor 54 that is positioned insidecf an insulating sleeve 61. A rod-line conductor 55 slides within the tubular conductor 54, and is provided with longitudinal slots 56 in its upper end, so that electrical contact is supplied by means of a solid rod 62, which extends through the remainder of the tool and is coupled to a second tubular conductor 64 at its lower end, shown in Figure 5b. Suitable in-sulating washers 63 and 68 are provided for preventing the conductor rod 62 from shorting against the metallic housing of the anchoring means. The outer surface of the rod 62 is insulated by a plastic coating. The circuit is completed by rod member 65, which fits into the tubular conductor 64, and connects with the female electri,cal connector 67. A flexible insulated electrical cable may be used in place of telescoping rod conductor described above. The cable may be connected to an ex-tension of the tubular conductor 54 at the upper end, and to ?n extensic)n of the tubul2r conductor 64 at the 'ower end.
The anchoring means 13 is provided with a coil spring 70 which forces the collet fingers 75 downwardly. The ~ 07 ~ ~ Z
downward force of the spring maintains the ramp surface 74 of the collets in contact with the ramp 73 of the housing 49 of the anchoring means 13. An upward pull on the wireline, attached to the threaded end 50 of the connector, will pull the housing 49 up and the ramp ; surface 73 will force the collet fingers 75 to grab the fishing neck 44 of the downhole anchoring sub 12, shown in Figure 3. When it is desired to release the anchoring, the tension on the wireline is removed to allow the sinker bars 14 to force the housing 49 down, so that the collet fingers 75 may move outwardly and release from the fishing neck 44. A suitable cam ar-rangement is provided so that on the succeeding upward pull, the housing 49 is p~evented from moving upward with respect to the collet fingers 75 and again forcing these fingers into a locking position. The cam arrangement is formed by cam pins 71 and cam slots 72 formed in the inner portion of the tool. Vent ports 76 are formed in the body of the connector to vent the interior of the connector and equalize pressures. A more complete description and illustration of the locking and release mechanism of the tool is shown in the pamphlets issued by the manufacturer Taylor Made Oil Tool Company of the wireline overshot tool that has been modified to the anchoring means 13.

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As can be seen in the brief explanation above, t'ne an-choring means 13 can be lowered into the well until the collet fingers 75 are positioned over the fishing neck 44 of the downhole anchoring sub 12 of Figure 3, and the female electrical connector 67 has engaged the male electrical connector 40. The wireline can then be pulled upwards to both tension the wireline and move the anchoring means 13 into a locking position. When it is desired to release the means 13 from the anchoring sub 12, the tension can be removed from the wireline and allow the means 13 to release the collet fingers 75.
Subsequently, the means 13 can be withdrawn from the interior of the drill string . This permits connecting and disconnecting the anchoring means 13 without apply-ing tension to the means 13. Thus, the possibility of the anchoring means 13 rebcunding in the drill string due to the sudden release of the tension on the wire-line is eliminated. The sudden rebounding of the down-hole anchoring means 13 can cause the wireline to become tangled in the drill string and prevent its removal.
Referring finally to Figure 6, there is shown an alternative downhole anchoring means 13. This means is a modified wireline overshot manufactured by Otis Engineering Corporation of Dallas, Texas. The means 13 is provided with a female electrical connector 113, which mates wi.th the male electrical connector 40 of the !~ -18-~L
anchoring sub 12 (as des^ribed already with respect to Figure 3). The connector 113 is in electrical com- ~
munication with the first sinker bar 14 (see Figure 1) .
that threads into the threaded end 112 of the means 13.
This electrical communication includes a flexible electrical cable (not shown) through passageway 114.
The anchoring means 13 of Figure 6 has a plurality of flexible fingers 100 that engage a flange 101 formed .
on the fishing neck 44 of the anchoring sub 12. The fingers 100 are forced into engagement with the flange 101 by tapered surfaces 102 at lower end of a cylindrical , outer member 103 of the means 13, when this means is lifted upwards by pulling the wireline 15 under tension.
The fingers 100 are disposed in longitudinal slots formed in the outer member 103, and pivot on the ring-shaped .
portion 108 of ~he outer member 1?3.
The anchoring means 13 of ~igure 6 is released by applying sufficient tension to the wireline to fracture the shear pin 104. To ensure uniform operation, the shear pin is provided with fracture grooves 105 at each end. When the shear pin fractures, the spring 106 will move the cylindrical member 103 downwardly relative to the fingers 100. S~bsequentl~, the wireline tensiorl is removed and the flexible fingers will disengage from the flange 101. After the fingers are released, the wireline can be withdrawn from the drill string.

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It will be appreciated that by a proper choice of the size of the shear pin 104, thedownhole anchoring means 13 can be made to operate at a tension less than the ultimate strength of the wireline but greater than the normal tension on the wireline.
Many modifications can be made in the telemetering system of the present invention. For example, a series of superimposed wirelines may be installed in the drill string. The lowest wireline thereof should have the greatest tension, and the tension should be lowered in each additional wireline. This ensures that the upper wirelines may be removed first, followed by the removal of the other wirelines in a descending order. The use of a series of individual wirelines is particularly desirable in deep bore~oles. When a series of wirelines are ~sed, each individual wireline is supported. This distributes the load of the wireline to a series of anchor points.
Further improvements can be made by combining the downhole anchoring sub and instrument sub in a single member. This would allow direct anchoring of the wire-line to the instrument sub.

Claims

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

1. A method for drilling a borehole and simultaneously passing electric signals between a level in the borehole and the surface, said method including the steps of: lowering a portion of a drill string into the borehole, said portion comprising a plurality of interconnected drill pipe sections; lowering through the interior of said portion of the drill string a wireline comprising an insulated electrical conductor adapted for transmitting electric signals, said conductor being provided at both ends thereof with an electrical connector; releasably coupling the lower electrical connector of the conductor with an electrical connector arranged in the interior of the drill string, and releasably anchoring the lower end of the wireline to the drill string; releasably anchoring the upper end of the wireline to the top of said portion of the drill string near the upper end thereof, such that the wireline is maintained under tension, and that the upper electrical connector thereof is arranged for transmission of signals between this upper connector and electrical coupling means carried by the upper end of the upper drill pipe section of the said portion of drill string; adding drill pipe sections to the portion of drill string present in the hole, whilst lowering the drill string in the hole, each of said sections containing an insulated electrical conductor electrically connected at each end of the section to an electrical coupling means arranged to cooperate with the electrical coupling means of adjacent sections for trans-mission of signals between the coupling means; and transmitting electric signals along the conductors, connectors and coupling means.

2. The method of claim 1, including the step of releasing the anchor-ing of the lower end of the wireline by increasing the tension exerted to the wireline to a value less than the breaking strength thereof, followed by lowering the tension to a value approximately equal to zero near the lower end thereof.

3. The method of claim 2, wherein the wireline is removed from said portion of the drill string before removing the drill string from the bore-hole.

4. The method of claim 1, wherein prior to the step of adding further drill pipe sections and after the steps of lowering, tensioning and anchor-ing the wireline in the lower portion of the drill string, a further portion of drill string is added and lowered in the borehole, whereafter a second wireline is lowered, tensioned and anchored in said further portion of drill string, and the adjacent ends of the conductors of the two wirelines are releasably electrically coupled.

5. The method of claims 2 and 4, wherein the release tension required for releasing the lower anchor of the upper wireline is lower than the tension required for releasing the lower anchor of the lower wireline.

6. An apparatus for telemetering information from an instrument pack-age in an instrument sub situated in a borehole while drilling the borehole, using a drill string comprising said instrument sub and carrying a drill bit, said apparatus comprising: a wireline containing at least one electrical conductor, said wireline extending through the interior of a lower portion of the drill string; a downhole electrical connector arranged in the interior of said portion of the drill string and secured thereto; an electrical connector electrically coupled to the lower end of the conductor in said wireline, and adapted to releasably engage the downhole electrical connector for transmission of signals; anchoring means for removably securing the lower end of the wireline to the portion of the drill string such that the wireline can be axially tensioned; anchoring means for removably securing the upper end of the wireline to the portion of the drill string such that the wireline is axially tensioned; a plurality of interconnected drill pipe sections forming the other, upper portion of the drill string, each pipe section having an insulated electrical conductor extending therethrough and being electrically connected at both ends thereof to electrical coupling means that are arranged for the transmission of signals between the coupling means and the electrical coupling means of adjacent pipe sections; and electrical coupling means electrically connected to the upper end of the conductor in said wireline and arranged for the transmission of signals between the coupling means and the electrical coupling means of the lowermost of said plurality of pipe sections.

7. The apparatus of claim 6, in which the instrument sub comprises a tubular member adapted to be included as a section of the drill string, a downhole anchoring means comprising a cylindrical member disposed coaxially within the tubular member, and a downhole electrical connector comprising an upwardly projecting, pin-type electrical connector disposed to be releasably engaged by the electrical connector that is electrically coupled to the lower end of the conductor in the wireline.

8. The apparatus of claim 7, wherein the downhole electrical connector is disposed in a separate sub member adapted to be included as a section of the drill string, said separate sub member having electrical coupling means arranged in signal-transmitting relationship with electrical coupling means of the instrument sub.

9. The apparatus of claim 6, wherein the means for anchoring the upper end of the wireline comprises: an anchoring sub adapted to be assembled as a part of the drill string; a cylindrical support member mounted co-axially in said sub; a wireline connector and terminal member adapted to receive the terminal on said one end of the wireline; a plurality of finger members pivotably mounted on the upper end of said wireline connector and terminal member; and biassing means mounted on the connector and terminal member and disposed to bias the finger members towards a retracted position that permits the connector and terminal member to pass through the cylindrical support member, said fingers being movable to an extended position where they engage the upper end of the cylindrical member and prevent said con-nector and terminal member from passing downwardly through the cylindrical support member.

10. The apparatus of claim 9, wherein the anchoring sub comprises an electrical connector in its upper end, and means are provided for forming an electrical connection with electrical coupling means arranged at the lower end of the lowermost of said plurality of pipe section.

11. The apparatus of claim 10, wherein the connector and terminal member has a central passageway for receiving an electrical conductor for connecting the electrical conductor in said wireline with the electrical connector disposed in said sub.

12. The apparatus of any one of the claims 6-8, having at least one spacer member disposed between the upper end of the wireline and the upper anchoring means to adjust the length of the wireline.

13. The apparatus of any one of the claims 6-8, having at least one weighting member disposed between the lower end of the wireline and the lower anchoring means.