EM-MWD (electromagnetic-measurement-while-drilling) transmission system for prolonging antenna lower arm

A transmission system and antenna technology, applied in the field of wireless electromagnetic transmission, can solve the problems of affecting the transmission distance and the transmission performance, and achieve the effect of extending the transmission distance and improving the transmission performance.

Inactive Publication Date: 2013-09-18
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

From theoretical and numerical simulation analysis, the length of the lower arm of the extremely asymmetric

Method used

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  • EM-MWD (electromagnetic-measurement-while-drilling) transmission system for prolonging antenna lower arm
  • EM-MWD (electromagnetic-measurement-while-drilling) transmission system for prolonging antenna lower arm
  • EM-MWD (electromagnetic-measurement-while-drilling) transmission system for prolonging antenna lower arm

Examples

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Example Embodiment

[0019] In the transmission process of the existing EM-MWD system, a drill rod is used as a dipole antenna, and the length of the lower arm L2 is usually much smaller than the length of the upper arm L1, so the length of the lower arm has a greater impact on the transmission performance. The influence of the length of the lower arm on the transmission performance is investigated through simulation. The hypothesis model is as follows: take the transmission frequency f=5Hz, the input power added to the two ends of the drill pipe is 1W, the horizontal length of the receiving antenna on the ground is 60m, and the formation conductivity It is 0.05S / m. At this time, the relationship between the voltage received on the ground and the length of the lower arm is as follows figure 1 . From figure 1 It can be seen that increasing the lower arm can significantly increase the received voltage. When the lower arm is increased from 10m to 200m, the received voltage can be increased by about 10...

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Abstract

The invention provides an EM-MWD (electromagnetic-measurement-while-drilling) transmission system for prolonging an antenna lower arm. The system comprises drill stems, a drill collar, a drilling tool, an EM-MWD module, an electromagnetic signal receiving module, a relay emitting module and a relay receiving module, wherein the EM-MWD module is arranged between the drill stems; the drill stem above the EM-MWD module serves as an antenna upper arm; the drill stem below the EM-MWD module, the drill collar and the drilling tool form the antenna lower arm; the relay emitting module is arranged between the drill stems and the drilling tool; the relay receiving module is arranged below the EM-MWD module and is connected with an electromagnetic signal emitting module in the EM-MWD module through a transmission line. The transmission performance is improved by prolonging the dipole antenna lower arm of the current EM-MWD system. The relay emitting module and the relay receiving module are added to the two ends of the antenna lower arm so that the information of a detector or a sensor can be still transmitted to the EM-MWD module in a wireless way after the lower arm is prolonged.

Description

technical field [0001] The invention belongs to the technology of transmission while drilling, in particular to the technology of wireless electromagnetic transmission of signals while drilling. Background technique [0002] In oil exploration and other geological drilling projects, the electromagnetic measurement-while-drilling (EM-MWD) technology, which uses metal drill pipe as an asymmetrically excited dipole antenna to realize logging-while-drilling signal transmission, is one of the research focuses in recent years. This method overcomes the shortcoming that mud pulse cannot be applied in air drilling, and has no requirement on mud quality. In this system, the drill pipe is used as the antenna, and an insulating short is added to the upper end near the drill bit, and electric excitation is applied to the upper and lower ends of the insulating short. Therefore, the drill pipe used as the upper arm of the antenna and the drill tool used as the lower arm of the antenna fo...

Claims

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Application Information

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IPC IPC(8): E21B47/13H04B7/14
Inventor 孙向阳聂在平
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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