Passive suppressing method for downhole noise and echo for sound transmission technology of drill string

Abstract

The invention relates to a passive suppressing method for downhole noise and echo for sound transmission technology of a drill string, which belongs to the technical field of downhole data transmission in the drilling process and solves the problems that the acoustic signal transmission performance of the drill string is reduced due to low-frequency noise and echo caused by the downhole noise, the discontinuous structure of the drill string and the like in the prior art. Based on the spectral response characteristics of a comb filter of a periodic pipe structure, the method utilizes a sound insulator structure with a periodic groove to realize the passive isolation and suppression of the upstream noise and echo in the drill string at certain frequency band, so that the signal to noise ratio for receiving signals can be improved, the transmission rate is improved, the well logging cycle is shortened, and drilling cost is saved. Moreover, the method has the characteristics of higher low-frequency sound insulation band width and simple structure.

Description

technical field [0001] The invention belongs to the technical field of downhole data transmission in the drilling process, and specifically relates to a downhole noise and echo passive suppression method for drill string acoustic transmission technology, which is used to effectively suppress the uplink in the drill string channel in logging while drilling. The influence of downhole noise and echo interference from the bottom of the drill string on the performance of acoustic transmission signal reception. Background technique [0002] As a new method to replace the traditional wireline logging, downhole information transmission technology in logging while drilling has become an international research hotspot. The currently widely used mud pulse technology has the disadvantage of very low transmission rate, generally only 10bit / s, and its signal-to-noise ratio is more easily affected by drilling fluid and field noise. Therefore, as an optional underground high-speed data tra...

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Problems solved by technology

However, the sound insulator structure proposed above is mainly used for acoustic logging, that is, to detect formation compressional waves by eliminating drill collar mode waves in acoustic logging while drilling, and some studies have not clarified the specific structure and its influencing factors for downhole practical applications. , which is also different from the detection requirements of the LWD acoustic wave communication for the longitudinal wave or stress wave in the drill string in this patent, but provides related solutions

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