In-situ measurement and analysis of pores are helpful to understand the properties of rocks. However, continuous quantitative analysis of pores in whole borehole is still difficult. Borehole camera technology can capture the borehole wall image of the whole well section by going deep into the borehole, which provides technical conditions for the measurement and analysis of pores. In this paper, a continuous measurement method of rock pores based on borehole camera technology is introduced. According to the characteristics of the optical image of borehole wall, a method of pore recognition and analysis is proposed. Specifically, the influence of redundant information on pore recognition is eliminated, and then the pores are accurately recognized by binarization and morphological operation. Based on the results of pore recognition and the coordinate information provided by borehole wall image, the calculation methods of surface porosity and line porosity are proposed, and the statistical analysis of pore distribution is realized according to the calculation results. In addition, the morphological characteristics of pores are also discussed. This method realizes the accurate recognition and quantitative calculation of pore structure based on borehole wall image, and provides a new method for continuous analysis of pore structure in the whole well.
In order to improve the accuracy and efficiency of deep in-situ stress measurement, based on the wall collapse in deep borehole, a deep borehole in-situ stress measurement method based on multi-array ultrasonic scanning technology is proposed in this paper. The solution idea of using the combination of multiple elements for borehole contour scanning is put forward, and a multi-array ultrasonic scanning technology suitable for fine horizontal section scanning of deep geological borehole contour is formed. Through the analysis of the calculation principle of hole wall caving method and the derivation of multi-array element ultrasonic scanning solution algorithm, a multi-array ultrasonic scanning device is developed by using the effective fusion of multi-array ultrasonic full waveform scanning signals and the reconstruction of horizontal section contour. The measurement method of in-situ stress in deep borehole combined with hole wall caving method is studied. Finally, the feasibility and accuracy of this method are verified by physical experiments. The results show that: the effective fusion of multi-array ultrasonic full waveform scanning signals and horizontal section contour reconstruction can break through the limitations of conventional in borehole probe placement and in borehole medium sound velocity calibration, and improve the fine reconstruction and accurate measurement of 360° wall shape. The multi-array ultrasonic scanning technology can obtain the borehole shape data at any borehole depth, and then obtain the three-dimensional shape measurement of borehole wall, which can provide a new technical means for the three-dimensional detection of borehole wall and in-situ stress measurement.
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