Array acoustic logging head wave arrival time determination method and device

Abstract

The invention provides an array acoustic logging head wave arrival time determination method and device, and the method comprises the steps: carrying out the local autocorrelation analysis and local standard deviation analysis of the full-wave waveform data of a depth of a pre-designated reference channel, and generating a local autocorrelation attribute channel and a local standard deviation attribute channel; combining the local self-correlation attribute channel and the local standard deviation attribute channel according to a preset weight to obtain a combined attribute channel; calculating the energy ratio of the combined attributes in the front and back time windows at each sampling point in the preset time range on the combined attribute channel, and taking the time corresponding to the sampling point with the maximum energy ratio as the head wave arrival time of the reference channel; and performing cross-correlation analysis on the data in the preset window length at different waveform recording times of the other channels and the data in the preset window length of the reference channel, and taking the waveform recording time corresponding to the maximum value of the correlation coefficient on each channel as the head wave arrival time on the corresponding channel, so that the head wave arrival information is effectively highlighted, the rapid and accurate extraction of the head wave arrival time is realized, and the effect is relatively good under the condition of low signal-to-noise ratio.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration, in particular to a method and device for determining the arrival time of the first wave of array acoustic logging. Background technique [0002] During the drilling process, the formation damage caused by mechanical collision or stress release, the change of pore fluid properties caused by mud invasion, and the expansion of clay minerals due to water absorption may cause the elastic wave velocity of the formation near the wellbore wall and far away from the wellbore wall to be different, which is called formation Radial change in velocity. Analyzing the radial variation of formation velocity is of great significance for estimating formation stress, evaluating wellbore stability, predicting perforation penetration depth, and optimizing formation fracturing design. P-wave traveltime tomography technology is an effective means to analyze the radial variation of formation velocity. T...

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Problems solved by technology

[0003] At present, the methods for determining the arrival time of the first wave mainly include threshold detection method, difference detection method, sliding time window method, long and short time window energy ratio method, etc. The results of the above methods are seriously distorted in the case of low signal-to-noise ratio data. Strong manual intervention The manual selection of the first wave arrival time seriously affects the accuracy and efficiency of the first wave arrival time extraction

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