1. Cables for field geophysical operations
Cables are meant for assembly and connection of measuring devices and nutrition devices in different geophysical lines applied in field conditions including seismic cables. Cables of this group are divided into signaling power and therm-pressure steady.
Signal - power cables can be classified by the number and cross-section of strands, and by breaking strength. By the number of strands the cables can be one and two-stranded. By cross-section signaling-power cables have the following gradation: 0,35; 0,5; 1,0; 2,5; 4,0 and 6,0 mm2. By their breaking strength signaling power cables can be divided into cables of normal strength (copper strands) and strengthened (steel copper strands).
By construction signaling power cables are produced from copper or steel copper current-conducting strands, and isolated light-stabilized with polyethylene of low pressure. The constructions of cables and their technical parameters are given in table #4.8.1.
Decoding of letter designation of signaling power cables is done the following way:
G - geophysical
P - wire (the second letter), polyethylene isolation (the last or one before the last letter
M - copper wires in a strand
S - steel wires in a strand
O - lightened
An example of reference designation: GPSMPO 1,0 - geophysical wire with steel copper current-conducting strand with cross-section 1,0 mm2, in isolation out of polyethylene, lightened.
Cables therm-pressure steady are aimed at manufacturing geophysical probing cable, working at alternating voltage up to 500 W and at temperature up to +200оС.
By construction therm-pressure steady cables are produced from steel copper (SC) or copper steel (CS) current-conducting strands with cross-section 1,5 mm2 isolated with copolymer of propylene (+150оС) or fluorine plastic (+200оС), steel and copper wires are put into different layers.
An example of reference designation:
TBP 1,5-150-CS - therm-pressure steady cable with steel copper current-conducting strand (inner layer out of steel wire and outer layer out of copper wire) with cross-section1,5 mm2 in isolation out of copolymer of propylene.
TBP 1,5-200-SC - therm-pressure steady cable with copper steel current-conducting strand (inner layer out of copper wire and outer layer out of steel wire) with cross-section1,5 mm2 in isolation out of fluorine plastic.
Fig.S.8.1. Outer view of geophysical wires
Technical parameters of cables are given in table # S.8.1, and examples of their constructive modification in Fig.S.8.2.
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With inner layer out of steel wires and outer - out of copper |
With inner layer out of copper wires and outer - out of steel |
Combined steel-copper layer |
Fig.S.8.2. Example of modifications of geophysical cables. 1 - steel wire, 2 - copper wire, 3 - insulation.
2. Seismic Cables
This type of cable is created for land seismology in field conditions in communication lines with seismic stations, linear channelizing and telemetric stations at min working temperature up to -50оС.
Seismic cables are classified by the following main attributes:
- number of strands (pairs) - can comprise from two to two hundred;
- flexibility - are divided into two groups: normal flexibility (one-wire current-conducting strands) and increased flexibility (multi-wire current-conducting strands);
- breaking strength - are also divided into two groups: normal strength and increased strength (cables with a logging element).
Construction of seismic cables:
Logging element (in cables with increased breaking strength) is produced from high-impact threads (SVM-thread, Armos, Kevral), that allows to add higher breaking strength to cable without changing its flexibility. Depending on a cable construction, logging element can be covered by a jacket from thermoplastic polyurethane.
Current-conducting strand is manufactured in three variants:
- Steel-copper strand produced in a form of joint of 4 steel zinced wires with diameter 0,25mm. Steel-copper modification of strand is as a rule applied only in cables KS-2S and KS-3S.
- One-wire strand insulated of polyurethane-nylon (PETVL-1-155), with diameter 0,335mm.
- Multi-wire strand produced in a form of joint of 7 copper soft wires with diameter 0,12mm.
Insulation of current-conducting strands is made out of copolymer of propylene.
Filler - insulated compound that prevents entering of water into cable. The filler is applied at customer's demand.
Dividing thread - cotton thread of different colors divides layers. Dividing thread is put into a cable with more than two layers.
Coil - ethylene terephthalate tape, serves for binding of cable core.
The jacket in seismic cables is produced from thermoplastic polyurethane, which possesses increased friction resistance, freeze resistance, flexibility and resistance to mould.
Examples of construction of seismic cables and their outer view are given in Fig.S.8.3.
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Cable KS-3S - for connection of geophone to communication line of seismic stations; 1 - steel wire, 2 - copper wire, 3 - jacket |
Cable KSTGA-16 - for application in communication lines with digital seismic stations of Input/Output type; 1 - logging element (Kevlar thread), 2 - twisted pairs, 3 - jacket |
Cable KSL 100-EM-SU - for application in seismic stations with a line division of channels; 2 - twisted pairs, 3 - jacket |
Fig. S.8.4. Outer view of seismic cables
