Downhole seismic source

Abstract

The invention provides a downhole seismic source, comprising an upper cylinder body, a middle cylinder body, and a friction slip arranged between the upper cylinder body and the middle cylinder body,and furthering comprising a slip mandrel arranged corresponding to the friction slip, and an adjusting ring sleeving the slip mandrel. The adjusting ring is in threaded connection with the slip mandrel so as to move in the axial direction of the slip mandrel, and therefore the pre-tightening force of the friction slip can be adjusted. The invention discloses the downhole seismic source. Through arrangement of the adjusting ring, the pre-tightening force on the friction slip can be adjusted by shifting and rotating the position of the adjusting ring so as to adjust the locking force of a locking mechanism, so that the strength of a vibration signal can be adjusted, and a standard vibration signal can be provided for borehole anti-collision monitoring and while-drilling earthquake technologies and is used for predicting the characteristics of a stratum in front of a drill bit and helping to identify the downhole condition.

Description

technical field [0001] The invention relates to the field of petroleum drilling engineering, in particular to a downhole seismic source. Background technique [0002] In drilling operations, it is especially necessary to predict formation information ahead of the drill bit. Both Drill-Bit SWD and VSP While Drilling based on seismic technology while drilling rely on conventional ground sources (such as air guns, vibrators or explosive sources) or unconventional downhole sources The vibration signal generated by (drill bit vibration) is collected by the sensor and analyzed and processed to obtain the relevant formation characteristics in front of the drill bit. Along with widening and extension of the application range of the seismic technology while drilling, the Chinese patent literature with the publication number CN101235716B discloses a kind of borehole anti-collision warning system based on drill bit vibration wave. ) to predict the formation characteristics in front o...

AI Technical Summary

Problems solved by technology

[0003]Although the above two technologies or methods have certain feasibility and reliability, there is currently the problem that the strength of the drill bit as a downhole seismic source is insufficient, and its application range is limited. limit

For example, when the drill bit encounters shallow formations with poor diagenesis, deep well sections or when drilling with PDC bit, the vibration signal of the drill bit vibration source collected is weak, and when the vibration and noise of the well site environment are too large , there are noise signals that are difficult to eliminate in the process of data processing

Therefore, these factors limit the application range of seismic technology while drilling and borehole anti-collision monitoring technology

[0004] Among the existing downhole seismic sources, in addition to the unconventional downhole seismic source such as the drill bit, a frequency-sweeping pulse jar tool has been developed abroad as the downhole seismic source. In the literature, the frequency-sweeping pulse shock tool is used instead of the drill bit as the seismic source. Although the limitation of the bit seismic while drilling is partially overcome, the vibration signal generated by it is not a characteristic standard signal, and the frequency (11-19 Hz) is relatively high. In addition, its application depth is limited, which is not enough to generate enough energy in deep well sections. Therefore, the application of this tool in seismic technology while drilling has the problems of difficult to effectively identify vibration signals and limited application range

In addition, the Chinese patent with publication number CN102817567B discloses a downhole repetitive shock generating device and method for oil and gas drilling. The downhole repetitive shock generating device involved in this document is a mechanical downhole seismic source. Due to its limited tensile strength, only the indoor simulation test of the prototype has been carried out, and there are no relevant reports on its application in underground mines as a seismic source.

Images