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That is a new group of the logging armored cables, distinctive special feature of which is the presence of information channels out of one or several optical fibers. The appearance of this group of cables resulted from new requirements to the transfer of much information that cannot be carried out on the basis of traditional constructive solutions. Actually, as it has already been mentioned in paragraphs 4.2, 6.4 traditional geophysical cables were capable of transferring of relatively small volume of information basically in the frequency range 50-100 kHz. The cables with the coaxial line possess best characteristics, but also they have sufficiently high attenuation factor with the frequencies of more than 1 MHz.

Cables with the fiber-optic communication channel have better characteristics (table S.4.3.) in comparison with traditional cables in both what concerns on fading of signal and on the noise protection, that makes possible the realization of such technologies as tele-inspection of wells, the vertical seismic survey of wells with the equipment of new generation, the work with the deep water descent vehicles, etc.

Another important property of multimode optical fiber is the possibility of measuring such characteristics as temperature, pressure, the radiation spectrum of wells through reflected optical signal in the cable. In this case, the cable with VOKS put down into a well, is the distributed sensor (for more detailed information visit: http://www.insysltd.ru/), which gives the possibility to obtain the thermogram of well in the real regime of time without stopping its work.

We should draw attention on the specific conditions, in which geophysical cables work, namely:

- constant stretching efforts of high values;

- high ambient temperature;

- external pressure to 50 to mPa;

These factors demand increased requirement from the constructions of optical cable in comparison with the usual cables for the horizontal padding. In connection with this the optical fiber cables for the wells have the following distinctive features, which make it possible to ensure high breaking strength at small relative elongation of the cable:

1. the usage of a highly carbonaceous rope as the cable armature wire with the breaking strength of 190 kg/mm?; superimposed with the preliminary preformation,
2. the application of a metal tube as the module jacket for the protection OV, guarantees the cable's work ability at high pressures, twisting strains, bend and tension; furthermore, 3) special construction and technology exclude the possibility of the runoff of the hydrophobic filler downward of cable;
3. Characteristics and the type of the optical fiber (one-mode or multimode) of the fiber, used in the cable, can differ depending of the needs of the client.

The material of tube can be used as the current-conducting strand, since metal tube is isolated and it can serve as the electrical communication channel, which gives the possibility to apply the standard geophysical equipment.

The core of multi-stranded cables is the combination of the optical communication channels and current-conducting strands. The quantity of current-conducting strands, their cross section and material, and also quantity and form of optical fibers, are selected in correspondence with the concrete requirements of customer. Logging optical fiber cables are produced also with the outer coating in the form of armored jacket, made from two differently directed layers of wire with coefficient of filling the layer 0,4-0,6 and poured with polymeric material. It should be mentioned that in comparison with the classical two-layered armor the armored jacket has the following advantages:

• better protects OV from the external pressure;
• the increased cable rigidity excludes the possibility of looping, it works better on the twisting, that is especially important for this group of cables;
• better protection from the aggressive environment;

smaller specific density of cable and accordingly smaller stretching loads. Typical constructions of the optical fiber cables produced by "Pskovgeocable'" are given in Fig. S.4.1 and S.4.2.

Fig.S.4.1. Optical cable with 1 communication channel	Fig.S.4.2. Optical cable with 3 communication channel and with 3 copper conductors

Basic elements of construction:

1 - optical communication channel.
2 - hydrophobic filler.
3 - copper tube.
4 -cover.
5 - current-conducting strand
6 - isolation
7 - filling element
9,10 - logging elements from steel âûñîêîóãëåðîäèñòîé wire
11 - outer jacket.

Basic characteristics of optical fiber cables are given in table S.4.1.

Main Properties of Armored Optical Fiber Cables*

Table S.4.1

*Cable optical characteristics correspond to the type of optical fiber applied

Table S.4.2 give characteristics of the optical fibers applied

Table S.4.2

Comparison table of attenuation coefficients of simple cables and cables with FOC.

Table 4.4.3

Fig. 4.4.3. Outer view of optical cables

KG (3x1,5+3õSMF)-60-120AJ
KG (5x1,5+2xSMF)-60-120AJ
KG 1xMMF-8-90