single conductor re head instructions

Single Conductor Rehead Instructions and Troubleshooting

Mount Sopris Instrument Co., Inc. Golden Colorado, U. S. A.

October 10, 2002

Table of Contents

Rehead Instructions..................................................................................................................... 3 Disassembly......................................................................................................................... 3 Strain Relief ......................................................................................................................... 3 Electrical Connections ......................................................................................................... 6

Wireline and Cable head Troubleshooting .................................................................................. 8 Introduction: ......................................................................................................................... 8 Failure mechanisms:............................................................................................................ 8 Preventative maintenance: .................................................................................................. 9 Visual Inspection.................................................................................................................. 9

Logging cable ............................................................................................................ 9 Cable head external inspection................................................................................. 9 Cable head internal inspection.................................................................................. 9 Bulkhead.................................................................................................................... 10

Electrical Inspection............................................................................................................. 10 Ohmmeter tests......................................................................................................... 10 Test Armor continuity ................................................................................................ 12 Test Conductor continuity.......................................................................................... 12 Voltage Measurements ............................................................................................. 13

Parts Diagram...................................................................................................................... 14 Mt. Sopris Single Conductor Cablehead Assembly (2000-1448) ........................................ 14

Single Conductor Wireline Re-Head Instructions

Rehead Instructions Disassembly The 1/8" and 1/10" cable used in the MGX winch should be re-headed, at minimum, every 3 months. 1. Make a fresh cut on the cable above any kinked or badly worn portions. 2. Check cable insulation and continuity with ohmmeter. Strain Relief 3. Feed cable through in the following order: a) Protector spring p.n. 2000-0509 b) Clamping screw p.n. 2000-0155

STOP!!! HAVE YOU SLID THE PROTECTOR SPRING & CLAMPING SCREW ON THE CABLE?

4. Place clamping blocks in vice. Pull 10 inches (25 cm) of cable through the blocks and secure vise. 5. Unwrap the strands of outside armor wire only one strand at a time to the bottom of the sleeve.

Straighten the armor wire and bend the strands so they will lie perpendicular to the cable. It is essential to unwind only one strand of armor at a time. As the strands are unwrapped try to keep the strands in order as you proceed around the cable. This will insure no two strands cross within the cone and will provide a stronger assembly. The strands for the outer armor will unwrap in a counter clockwise direction. The strands should be picked from the cable as you proceed in a clockwise around the cable.

P/N 7000104E Mount Sopris Instrument Company 3


Here the outer strands are shown arrayed around

the top of the clamp blocks. The clamping blocks have been covered to provide better image quality. Note that even, non-overlapped spacing is easy to achieve because the outer sleeve is not in place. This is different than the method described in earlier rehead instructions.

6. Once the outer armor strands are unwrapped and spread evenly around the blocks gather the top of the strands into a loose bundle and slip the large cone, with its larger diameter opening up, over the strands. The strands should remain in the same basic positions without crossing. 7. Use some patience and arrange the strands, one by one, evenly around the outer sleeve.

8. Slip the brass sleeve over the inner cable small end first. Press the brass sleeve into the outer sleeve, making adjustments to thstrands as necessary.

e

9. Once the strands and sleeves are positioned slide the drive tube over the cable and tap the end of the tube to secure the parts. The sleeves should not be driven together

firmly at this time. Cut the free ends of the strands of the outer armor wire as close to top of the sleeve as possible.



10. Fan 10 of the 12 strands of inside armor as you did with the outer armor strands in step 6. However, for the inner armor the strands will unwrap in a clockwise direction and be picked as you proceed in a counter clockwise direction around the cable. The two remaining inside armor strands should remain wrapped around the inner conductor to be used as a ground. The following picture shows a remaining strand that needs one more revolution clockwise to put it in place. Note that the strands are somewhat kept in place by the stubs of the outer wires.

11. With the inner armor strands unwrapped and spread evenly around the brass sleeve slip the inner steel cone over the inner conductor and 2 ground strands

small end first. Press the inner cone into the brass sleeve, making adjustments to the strands as necessary.

12. Use the drive tube to secure the parts. At this point drive all the components firmly together. 13. Cut the free ends of the strands of the inner armor wire as close to top of the sleeve as possible. Slide the sleeve assembly into the cable head housing threading the center conductor and ground strands through the center hole. 14. Engage clamping screw threads into housing and tighten as far as possible. At least half of thread must be engaged to insure proper compression of cone and sleeve assembly. 15. Perform electrical tests on cable to verify that there are no shorts.



Electrical Connections

16. Remove 1 inch (25mm) of insulation from the end of the inner conductor.

17. Solder a 4" length of solid #26 wire to the end of the conductor as an extension wire. Place a thin film of Dow Corning silicone lubricant on the extension wire. 18. Insert the extension wire into the tapered end of a mecca boot and pull the center conductor through the boot (past the stripped portion). Cut the extension wire off leaving 7/32 inches (.56 cm) of bare wire. 19. Solder or crimp the MECCA socket onto the center conductor.



20. Pull the socket into the sleeve by gently pulling on the wire, while gripping boot in other hand. 21. Next crimp an AMP, connector, 321017 (MS P/N 21-230-545) onto the 2 inside strands of armor wire. If these wires are longer than necessary cut to desired length before crimping on AMP connector. 22. Attach armor wire to bulkhead using a 4-40 x 3/16 socket head stainless steel screw. On earlier models you may need to drill and tap the bulkhead for a 4-40 screw if it has not been modified already. 23. Place a thin film of silicone compound on raised surface of pin connector on bulkhead. Do not put silicone on pin surface or socket surface. 24. Push boot over MECCA pin on the bulkhead being sure pin goes into socket, not beside it. Excess lubricant may squeeze out. 25. Place the bulkhead into the housing being careful not to put any sharp bends in center conductor wire. Secure with 3 clamping screws. Note: The three screws that join the bulkhead and the housing/clamping nut together are shear screws that maintain the mechanical integrity of the cable head. Machining tolerances to allow field replacement of parts results in a “loose fit” between the bulkhead and the housing. This is normal. The three screws should not be over-tightened. Some wobble between the bulkhead and the housing is normal. Do not overt-tighten the bulkhead into the probe top. Wrenches should not be used, as hand tightening is sufficient.


Single Conductor Wireline Troubleshooting

Wireline and Cable head Troubleshooting Introduction:

Logging cable provides mechanical attachment and electrical connection between the logger and logging tool. As it is also exposed to the logging environment and is subject to mechanical stress when rigging up and down as well as during logging, it is perhaps the weakest link in the logging system. Logging cable and the cable head require routine maintenance and inspection. We recommend that you visually inspect the cable near the cable head and do a quick electrical check before each logging session. Complete mechanical inspection including disassembly and electrical tests should be performed at least once a month if used often. The more the system is used the more often these tests should be performed. If the system has been in storage for some time, perform a complete mechanical inspection with disassembly plus electrical tests before resuming logging operations.

When problems with a logging tool are encountered one of the first things that should be checked is the integrity of the wireline and its associated components, the slip ring assembly and cable head. The wireline system (and associated cables) takes the most abuse and is the most likely source of problems. Insuring that it is not the problem can save much time, energy and money later on. Failure mechanisms: Mechanical damage

The small diameter logging cable can be pinched which can cause strands of the inner armor wire to cold flow through the insulation around the conductor and create an electrical path, termed a short, between the cable armor and the cable conductor. This conductive path can measure from a few million ohms to a complete short. Depending on the communications method of the tool this can be a large or small problem. Different amounts of resistance between the armor and conductor have different effects on tool communications. On the extreme side the short may prevent the tool from getting enough power to turn on or if it does turn on there can be continuous data errors in digital tools or a loss of counts in pulse type tools which may show up as a drastic shift in calibration.

Corrosion damage

The logging cable armor consists of wrapped strands of steel wire and although it is coated at the wireline manufactures facility with a Krust inhibitor, it is subject to rusting particularly where the rust inhibitor has been wiped off during the re-heading process. Water tends to stay in the cable head and becomes trapped in the cone and sleeve assembly even when the cable head is packed with grease. The cable strands around the base of the cone and sleeve assembly rust and can become quite weak. This can result in the loss of a logging tool. Packing the cable head with grease helps extend the life of the cable head but cannot prevent rusting especially when used in a saline or caustic borehole environment.

Fluid Leakage There are three seals that are a part of the cable head assembly. The first and most obvious is the O-Ring seal that keeps fluid out of the top of the tool attached to the cable head. This seal can become brittle or soft from age. It can be damaged by fluid properties that can attack its Buna-N composition. It can be nicked by improper handling or abraded by grit. It must be kept clean and lightly lubricated with silicone grease. We recommend Dow Corning DC-111, DC4, 5, or Parker Super O Lube.

P/N 7000104E Mount Sopris Instrument Company 8 K rust inhibitor. A sticky, brown substance composed of oxidized wax and petroleum distillate.


The second seal is the mecca boot to mecca Kpressure seal at the bulkhead. This joint seals the borehole fluid from the electrical connection on the end of the wireline. The seal can be stressed by bending when it is installed into the body of the cable head. Over time this bend can allow small amounts of fluid to enter and corrode both the connector and the wireline conductor possibly resulting in an intermittent contact. The seal may also not be properly seated which could allow fluid to enter the connection. Leakage here can also show up as a high resistance short between cable conductor and cable armor. If allowed to dry the short may disappear until the next time it is lowered into fluid.

The third seal is the seating of the mecca pressure seal into the cable head bulkhead body. The mecca pressure seal must be tightly seated and the seat must be clean and lightly lubricated with silicone grease when it is installed. The mecca pressure seal is held in place by the hexagonal brass connector nut screwed onto the end of its shaft. If fluid leaks past the mecca pressure seal it will cause a short between the conductor and the body of the cable head. There is also a Phenolic insulator at the base of the rubber body of the pressure seal. It electrically insulates the pressure seal contact from the bulkhead. The insulator material absorbs water and will remain wet and can cause a short between the pressure seal and bulkhead. The bulkhead should be tested alone for shorts after removing it from the wireline connections.

Preventative maintenance: Visual inspection of armor

Armor has no broken strands. Armor has no severe kinks.

Ohmmeter checks of wireline continuity and isolation. Visual inspection of O-ring condition

O-rings are not worn or chipped or brittle and have adequate lubricant (grease).

Shelf life of Buna-N O-rings is only 5 years. Visual Inspection

Logging cable Inspect the logging cable for kinks, separated strands or other problems. Do this each time you log and pay particular attention to the 10 meters above the cable head. A strand that is separated slightly or sticking out of the wireline will eventually break causing problems. It is also a hazard to the operator handling the cable. The cable should be re-headed above such problem areas. Bends or kinks that are not to sharp may be unbent but you should test the cable for shorts with an ohmmeter before doing so.

Cable head external inspection Look at the O-ring, make sure the threads are clean of grit and debris, see that the

brass nut is secure and has an electrical insulating washer between it and the body of the bulkhead. Do not over tighten the brass contact nut. It is easy to strip the threads in this soft material.

Cable head internal inspection Remove the three socket cap screws, pull the bulkhead away from the body and

disconnect the mecca connector and boot. Unscrew the cable armor connection, AMP, eyelet from the bulkhead. Note the condition of the armor strands. Check that the mecca bulkhead is snug and fully seated in the bulkhead. Unscrew the cable, locking screw and slide the screw and cable spring away from the body. Inspect the condition of the cone and sleeves. Pay particular attention to the strands on the backside of cone and sleeve. If all looks good

P/N 7000104E Mount Sopris Instrument Company 9 K mecca pressure seal. Also known as a mecca bulkhead.


you can reassemble the cable head. Once you are done check the electrical properties to make sure everything is connected and no short was introduced.

Bulkhead The bulkhead is the section that seals the

electrical and mechanical connections between the borehole and the probe. It also provides the electrical connection for the wireline conductor and armor. Pay particular attention to its condition.

The bulkhead is a possible source of electrical shorts. This can be tested with an ohmmeter as described in electrical inspection. A loose contact nut can compromise the pressure seal allowing fluid past it. The Phenolic insulator at the base of the rubber part of the pressure seal will absorb water and is quite difficult to dry out. It should always be removed and inspected when disassembling the bulkhead.

The Bulkhead assembly is composed of a 21-808-500 mecca pressure seal with Phenolic insulator, 2000-1063 Bulkhead, 25-402-115 O-Ring, 2000-0164 insulator, 2000-0165 cablehead contact (brass nut). The photo shows the new style bulkhead with a bore that accepts the insulator. Older models do not have this bore and require insulator 2000-0166.

When replacing the mecca pressure seal make sure that you remove the brown Phenolic insulator from the bulkhead. It can become stuck inside. You can use the shaft of the mecca pressure seal inserted from the opposite end to catch the soft, Phenolic material and push it out. Warning: Do not over tighten the brass contact, nut, as it is easy to strip its fine threads.

On older units be sure that the insulation around the shaft of the mecca pressure seal extends slightly beyond the bulkhead when the seal is installed. The insulation prevents the shaft of the pressure seal from shorting to the bulkhead. When you cut the pressure seal shaft (usually with large wire cutters) you should dress the end of the shaft with a file so that the threads do not damage the brass contact nut threads when they are screwed together. When you cut the pressure seal shaft to length it should not extend beyond the end of the contact nut beveled surface when it is fully tightened. The flat side of the nut should be against the insulating washer. Electrical Inspection Two conditions must be met for the wireline to operate properly. 1) The wireline conductor(s) must be electrically isolated, in and out of fluid, from the wireline armor. 2) The wireline conductor(s) and armor must be electrically continuous, while stationary and in movement, from the cable head to the logging acquisition equipment.

Ohmmeter tests CAUTION: Always be sure that your meter lead connections to the system under test are good. Check the continuity of your meter leads by touching them together. When making measurements do not touch the meter lead contacts with your hands. Touching the leads can cause erroneous readings, as your skin is conductive especially when wet or sweaty. CAUTION: If you use a Megohmmeter style cable tester, which can produce 500 or more volts, you should first disconnect the slip rings from the system as the high voltage may damage the slip rings. Megohmmeters can be useful in finding shorts that cannot easily be reproduced or located by normal resistance measuring meters.



Checking electrical isolation You will need an ohmmeter capable of reading 20 million ohms of resistance or higher. Set the meter in the highest reading resistance range. Connect the meter test leads to the positive (+) and negative (-) terminals of the meter. Consult the meter manual for proper operation.

Remove any connection between tplace the acquisition equipment in the proper mode or switch setting that isthe acquisition and power electronics fromthe slip ring connection. Make sure that any power to the system under test iturned off. Consult your operating manual for details.

he slip rings and the surface, acquisition, equipment or

olates

s

ace moisture off of the cabl

Place one meter lead on the contact d.

ead.

igh

ng the meter, wiggle, push and pull the wireline vigorously where it enters the able he

If the meter indicates some high or low resistance leakage between the conductor and armor, disasse

Some shorts may occur only when the wireline is wet. If the problem only occurs when you reach a

e

isolate the problem to the wireline the next task is to determine where on the

wireline eline

r in

f

Wipe any surfe head with a dry cloth. Remove

any protector cap from the end of the cable head.

pin at the end of the cable heaPlace the other meter lead on the exposed, metal body of the cable hThe meter should read infinite ohms. Move this lead to the wireline armor. Itshould read infinite ohms. The readings may initially read some high resistance and then, within about five seconds, drift to an open/infinite reading. This is an indication of proper isolation. On meters capable of reading henough, there should actually be more than 200 million ohms of isolation between the wireline armor and conductor. If the meter reads any resistance then there is a problem. While watchic ad and at any points where there are kinks. Reverse the meter leads, and repeat the aboveprocedure. You should see the same indication.

mble the cable head and perform the resistance test on the separate components. Look for obvious bare spots on the conductor.

certain depth below water surface you can place the wireline in a bucket of water and let it soak awhile, periodically performing the above tests. Adding lots of salt to the water can enhance theffect.

If you can the problem is. The most common place is at the cone and sleeve that terminate the wir

armor. One approach is to cut off the cable above the cable head and any obvious kinks in the wireline. Re-test the resistance as above. If the cable is still shorted, look for further kinks deepethe wireline spool. Again cut off the cable above the kinks and re-test. If this does not resolve the problem you may be able to make the short worse by placing the bad part of the cable in a bucket osalty water. Monitor the meter while slowly placing the cable into the bucket. Again most problems are near the cable head.



Checking Wireline continuity

A sudden drop to zero of a tool measurement that uses a pulse type transmission may indicate a wireline continuity problem. The measurement may recover only to again drop to zero at random or periodic intervals.

This could be an indication of a bad slip ring assembly especially if the condition only occurs when the winch drum is moving but not if the system is stationary and only the cable head or other connections are wiggled. If the cable head is wiggled and the frequency drops to zero then the problem could be in the cable head or probe top.

Another symptom is that the acquisition initially reports a spike of counts, when power is applied, and then nothing. The spike is created by the up-hole power supply switching on and is not usually tool response. Note: this could also be a symptom of a non-functional tool, if possible operate the system with another pulse tool.

Testing wireline continuity is done using an ohmmeter, as above, set to a low range such as 100 or 200 ohms full scale. As before, make sure that all power to the system under test is turned off.

Test Armor continuity Identify a connection to the acquisition

end of the wireline ARMOR. Connect one, meter lead there. Connect the other meter lead to bare metal at the cable head. You should read nearly zero ohms. Wiggle the wireline where it enters the cable head and at any other suspect point. If there is a problem with the connection at the cable head, move that lead to the wireline armor. If there is now a positive connection then disassemble and inspect the cable head. If there is still a problem move the lead to the armor connection on the winch drum, then to the slip ring connection, wireline side, then to the slip ring connection, acquisition side. Alternately move the acquisition side meter lead closer, in like steps, to the wireline armor.

Test Conductor continuity Identify the Acquisition end of the

wireline CONDUCTOR. Connect one lead of the ohmmeter there. Connect the other meter lead to the cable head contact pin. The ohmmeter should indicate the wireline resistance, which is approximately 25 ohms per thousand feet of cable. Check your winch manual specifications for other values of wireline conductor resistance.

For both tests above, to isolate possible problems with the slip rings, rotate the winch drum several rotations and observe that the meter readings, as noted above, are stable and do not bounce around. The wireline conductor and armor are attached to one side of a terminal block on the winch drum side-plate. From the other side of the terminal block, wires go to the slip ring assembly on the end of the drum shaft. Make sure that the terminal block connections are relatively clean and dry. P/N 7000104E Mount Sopris Instrument Company 12


Voltage Measurements Warning: Potentially hazardous levels of voltage may be present on the cable head contact nut when the tool power is turned ON. Use extreme caution when handling the cable end while making measurements there. Only qualified personnel should perform this test.

One test of the logging system operation is to check the voltage at the cable head without the probe attached. If you know the operating voltage of the probe, for instance MSLog displays the voltage it will apply to the wireline in the Dashboard Tool panel, you can connect a D.C. voltmeter between the cable armor and the contact nut on the cable head to measure it. Connect the negative lead of the meter to the cable armor and the positive lead of the meter to the brass contact nut on the end of the cable head. Turn the tool power On. The picture indicates 67.9 volts for a 2PGA-1000 on 500 meters of wireline.

Note: MSLog does not indicate the polarity of the voltage applied to the wireline. Some tools use negative polarity to engage different operating modes or ranges and to open or close caliper arms or sample volumes.

You can perform the same test at the banana sockets on the side of the MGX II.

Connect the positive lead to the socket marked CONDUCTOR and the negative lead to the socket marked ARMOR. You should have the same readings. This test is particularly appropriate when the tool is attached but does not insure that the voltage is available at the tool top.

Note that some tools use alternating voltages, particularly tools measuring formation resistance or resistivity. This test may not be appropriate for those tools and may give ambiguous readings.

Tool connection Mount Sopris single conductor probes use a stainless steel spring plunger inside the tool top to make contact with the cable head conductor. Tests include pressing on the plunger to make sure it is free to move. Inspect the plunger for corrosion or moisture. Make sure the plunger and surrounding area is dry. Also measure the engagement of the cable head with the plunger to determine if it is adequate.



Parts Diagram

Mt. Sopris Single Conductor Cablehead Assembly (2000-1448)

2000-0164 Insulator

2000-0165 Contact

2000-1063 Bulkhead

25-402-115 O-ring

28-185-049 4-40 3/16 screw

2000-0444 M3x5 SHCS Qty. 3ea.

21-808-500 Mecca Pressure Seal

21-808-505 Mecca Connector

21-808-504 Mecca Boot

21-230-545 Conn, Lug, Amp

2000-1064 Housing, Cable head

2000-0155 Clamping Screw

Not shown (1 each): 2000-1452, Sleeve Outer 2000-1453, Sleeve Brass 2000-1454, Cone Inner

2000-0509 Cable Protecting Spring

16-201-006 1 Tube Lubricant, DC111 Silicone. To fill housing and coat seals.

Accessories: 2000-1526 Drive Tube 2000-1510 Clamp Blocks (2ea) 28-957-001 M6x1 grease fitting 28-185-549 M6x6 stainless steel set screw


single conductor re head instructions

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