Coaxial photoelectric composite cable for oil well

Abstract

A coaxial photoelectric composite cable for an oil well comprises an optical unit, a first insulating layer, an electric unit, a second insulating layer and an armor layer. The outer side of the optical unit is coated with the first insulating layer, the electric unit is spirally twisted on the outer side of the first insulating layer, and the electric unit and the optical unit are packaged in a split mode. The outer side of the electric unit is coated with a second insulating layer, and the internal gap of the electric unit is uniformly coated with a sealing water-blocking material. The outer part of the second insulating layer is provided with a double-layer armor layer, and the gap of the armor layer is filled with a high polymer. By means of the structural design, a small additional loss is kept in an optical fiber application, the problem that an optical unit and an electric unit of the oil well photoelectric composite cable are separated and packaged is solved, meanwhile, ultra-flexible small-bending-radius use of the composite cable is guaranteed, the stability of the overall structure is improved, use faults are effectively reduced, and the service life of the composite cable is prolonged.

Description

Technical field [0001] The present invention relates to the technical field of photoelectric composite cable technologies, and in particular to an oil well coaxial photoelectric composite cable. Background technique [0002] In recent years, with the continuous development of underground information visualization and imaging display technology, modern logging techniques urgently require data from more real, greater rock resistance, physical properties, oily and permeability of the well. Due to the influence of the harsh environments such as transport medium, design idea, manufacturing process, and underground, high-pressure, long-term logging cable transmission system has slowed, less information, small information, and large information, especially in ultra-deep wells. The attenuation of the signal and the mutual interference between the various signals between the lines have become more serious and have become a bottleneck problem of modern logging data acquisition systems. The...

AI Technical Summary

Problems solved by technology

[0003] At present, there are few types of photoelectric composite cables for oil wells in the market, and the stability of structural performance is immature, which is mainly reflected in the difficulty of controlling the additional attenuation of optical fibers under high temperature and high pressure and the unstable electrical properties of corrosion-resistant enhanced cables.

Common structures include: one structure is to combine optical and electrical units in a stainless steel tube. This structure often requires a stainless steel tube with a larger inner diameter to provide enough space. In order to meet the environment of the oil well (generally 70-150MPa pressure) , the outer diameter of the stainless steel tube is large, and it cannot withstand a large downhole pressure, which limits the use depth of the optical cable; another structure is to place the optical fiber in the stainless steel tube, and the electrical unit is wrapped with copper tape or laser welded copper tube. In the outer layer of the stainless steel tube, although this structure can reduce the overall outer diameter of the optical cable, the bending performance is poor, and it cannot meet the needs of small bending radius in the limited space of the oil well.

At the same time, when the optical fiber sensing and detection cables work at the same time, the stainless steel tube will be charged synchronously, resulting in only single optical fiber sensing or single cable sensing, and cannot work synchronously

[0004] In addition, in order to improve the application of oil well detection cables in more complex and corrosion-resistant environments, armoring materials with stronger corrosion resistance are often selected. However, there is a problem that the cable transmission cannot match the detection equipment during use.

Images