In order to provide higher efficiency of mining of oil and gas land deposits and to increase work efficiency in a well a certain type of construction have been introduced and became widely spread. That is the construction of well with slanting and horizontal hole, carried out through productive strata with the aim to increase the surface of gutter of oil and gas to well. Geophysical informative provision of such wells during their construction and in further usage is a very complicated problem due to technical difficulties in delivering of geophysical devices into horizontal parts of a well. One of the effective ways to deliver devices is their delivering with a help of rigid cable (cable line).
Compared to others, this way possesses the following advantages:
- not really huge technological labor input in a round-trip operation, because the time of logging in horizontal part with the help of rigid cable is practically equal to the time of vertical logging;
- receiving of information in real time;
- high reliability, thanks to a special geophysical cable with high breaking strength;
- possibility to apply standard devices;
- high mobility.
Rigidity of these cables (cable lines) is reached through increase in the number of layers of copper wire when every next layer is made of wire with larger diameter. Layers are put with a free distance that equals approximately to diameter of wire, with the further pouring with polymer. Cable lines are manufactured with variable cross-section (in order to create the pushing part in the end of cable and make it lightened and of smaller diameter in the upper part and lifter).
In 2002 under the license of "Volga-Ural Service Center "Neutron" Pskovgeocable Ltd started commercial manufacturing of cables with increased rigidity. During this period different constructions of cable lines have been developed and used successfully. They were developed on the basis of two basic trends:
1. Cable of variable cross-section KL 3-160/230-90AJ
Construction and specification of this cable are given in picture 4.3.1. Structurally the cables of this trend consist of three parts: logging, logging-pushing and logging-moved.
Upper logging part is a four-layered cable KG 3x0,75-160-150 with increased breaking strength. Functionally, the upper part plays a role of standard geophysical cable with increased breaking strength.
Middle rigid logging-pushing part is a six-layered cable KG3x0,75-230-90. Functionally, the middle part is aimed at creation of force-through effort at the expense of its own weight, because in comparison to the upper part its удельный вес is 2,5 times larger and it as well possesses significant axial stiffness.
Lower rigid logging-moved part is similar in construction with middle part with the difference that in the third and fourth layers the half of wires is deleted. It helps to decrease cable relative density and its tension with the walls of well. Functionally, lower and lightened part is created for directly delivering of geophysical device into the horizontal part of the well.
Usually, there are used cables which are 4000 meters in length, out of which the length of the middle part comprises 800 meters, of the lower part - 400 meters, with the whole length of the rigid part equal to 1200 meters.
As the practice shows, cables of such construction are guaranteed to come through a horizontal part (92?) with length up to 300 meters and through slanting part (75?) with the length up to 800 meters.
KL 3-160/230-90AJ
Picture 4.3.1. Construction and specification of cable line KL 3-160/230-90AJ
- Logging part
- logging-pushing part
- logging-moved part
|
№ |
Name of construction |
Material |
Diameter, mm |
|
1 |
Conductor |
Copper, AWG 18, 7х0.38mm, (0.75 мм2) |
1,1 |
|
2 |
Insulation |
TEFLON FEP D=0.4 мм., TEFZEL-280 D=0.4 мм, (DUPONT trademarks) |
2,7 |
|
3 |
Filler |
Silicon compound, thread, and tape binder |
5,7 |
|
4 |
1st lay armor |
Steel galvanized wire 17x1,1 mm, grade 190 kg/mm2 |
7,6 |
|
5 |
2nd lay armor |
Steel galvanized wire 20x1,3 mm, grade 190 kg/mm2 |
10,2 |
|
6 |
3rd lay armor |
Steel galvanized wire 24x1,35 mm, grade 190 kg/mm2 |
12,9 |
|
7 |
4th lay armor |
Steel galvanized wire 24x1,75 mm, grade 190 kg/mm2 |
16,4 |
|
8 |
Inner sheath |
Polyethylene D=1,8 mm. |
20 |
|
9 |
5th lay armor |
Steel galvanized wire 24x1,3 mm, grade 190 kg/mm2 |
22,6 |
|
10 |
6th lay armor |
Steel galvanized wire 24x1,55 mm, grade 190 kg/mm2 |
25,7 |
|
11 |
Outer jacket |
Polyethylene D=3,2 mm. |
31,0 |
Overall cable length - 4000 meters out of which:
- logging part - 2750meters;
- logging-pushing part - 800 meters;
- logging-moved part - 400 meters.
Cable weight, upper part 1200 kg/km.
Cable weight, middle part 2150 kg/km.
Cable weight, lower part 2550 kg/km.
Picture 4.3.2. Cross-sectional drawing and structure of rigid part of cable line KL 3-160/230-90AJ
2. Cable of uniform cross-section KG 3x0,75-150-150 AJ
Cable of this construction has proved to be one of the best in field operations. It is much easier to work with these cables in the wells under pressure because it has the same structure along the whole length. Compared to cable KL 3-160/230-90 AJ, cable KG 3x0,75-150-150 AJ possesses a bit lower ability to penetrate into horizontal parts, but works just great in slanting holes. Construction and specification of this cable are given in picture 4.3.3.
KG 3x0,75-150-150 AJ
Picture 4.3.3. Construction and specification of cable line KG 3x0,75-150-150 AJ.
|
№ |
Name of construction |
Material |
Diameter, mm |
|
1 |
Conductor |
Copper, AWG 18, 7х0.38mm, (0.75 мм2) |
1,1 |
|
2 |
Insulation |
Polypropylene, D=0,6 мм |
2,7 |
|
3 |
Cores stranded |
|
5,4 |
|
4 |
1st lay armor |
Steel galvanized wire 17x1,1 mm, grade 190 kg/mm2 |
7,6 |
|
5 |
2nd lay armor |
Steel galvanized wire 20x1,3 mm, grade 190 kg/mm2 |
10,2 |
|
6 |
Inner sheath |
Polyethylene |
14 |
|
7 |
3rd lay armor |
Steel galvanized wire 20x1,1 mm, grade 190 kg/mm2 |
16,0 |
|
8 |
4th lay armor |
Steel galvanized wire 20x1,3 mm, grade 190 kg/mm2 |
18,6 |
|
9 |
Outer jacket |
Polyethylene D=1,5 mm. |
20,7 |
Nominal properties
Conductor resistance, no more 25 ohms/km
Minimum conductor resistance to insulation at 500 vdc 10000 mega ohms/kilometer
Cable breaking capacity, no less 150 kN
Max working temperature 120 degrees Celsius
Min working temperature -30 degrees Celsius
Cable weight 1100 kg/km
Choice of factory length of rigid cables used at the moment is stipulated first of all by tonnage of lifter, the majority of which have winch's volume up to 2,0 m?.
Taking into account our recommendations the firm "GIS-pribor M" developed geophysical lifter PKS-5G with rather increased winch lifting capacity. The lifters of this trend make it possible to work with cable KL 3-160/230-90AJ with length of rigid part up to 1900 meters with its diameter equal to 36 mm, the cable penetration ability into horizontal parts increased up to 500 meters.
A long-range cable with applying of more вместительная winch can be the cable on the basis of KG3x0,75-150-150AJ with diameter 28 mm and increased relative density. This cable would possess very high properties (not worse than those of KL 3-160/230-90AJ) concerning penetration capacity into horizontal holes because of the use of plumbic wire in the middle part.
More detailed information on geophysical lifters manufactured by "GIS-pribor M" can be found at http://www.gispribor.ru/
