Interface II well cementing quality evaluation method

Abstract

The invention discloses an interface II well cementing quality evaluation method. The method comprises the following steps that 1, wavelet transform time-frequency decomposition is performed on an obtained variable-density logging full-wave-train signal by utilizing a preset wavelet basis function to obtain time-frequency information of a full-wave-train waveform; 2, energy values of a stratum wave and a casing wave are separately determined according to time-frequency information of the full-wave-train waveform and combing distribution ranges of a time domain and a frequency domain corresponding to the obtained stratum wave and the obtained casing wave; and 3, an interface II well cementing state is determined according to the energy values of the stratum wave and the casing wave. According to the method, quantitative evaluation on the quality of interface II well cementing can be realized, compared with the prior art, an implementation mode of the method is simpler and faster, the result obtained through the method is more accurate, and therefore the method is more suitable for production requirements.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a second interface cementing quality evaluation method. Background technique [0002] Acoustic radiation variable density logging is a conventional cementing quality logging method at present, but according to the current industry standards, the evaluation of the second interface is often qualitative, and it is a very subjective evaluation system. The second interface is still a difficult problem. Some researchers have also proposed corresponding evaluation methods for the second interface (such as the method of combining naked-eye time difference and formation wave), but these methods have not been well applied and popularized. [0003] At present, the mainstream quantitative evaluation method for the second interface is the energy spectrum method. This method mainly performs Fourier transform on the full waveform data of variable density logging...

AI Technical Summary

Problems solved by technology

However, the premise of this method is that the frequency ranges of formation waves and casing waves must be accurately known, which is often difficult to achieve

In some work areas, the frequency ranges of formation wave and casing wave also overlap obviously, which will seriously affect the accuracy of evaluation

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