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This paper describes a perforating gun detonation monitoring system developed to meet the need for real-time monitoring of perforation effect in the petroleum industry. A high-sensitivity acceleration sensor, serving as the response module of the physical characteristics of the tubing vibration, acquires a set of vibration signals of the whole physical process during the impact after the detonation of the shaped charge. The jump point in the monitoring process is extracted by comparing the signal's short-time energy. The amplitude, energy, and envelope characteristics of the signal are then evaluated. From the time-frequency characteristics of the tubing vibration upon the detonation of the perforating gun, a judgment is made as to whether the perforating gun has detonated. Tubing vibration experiments were conducted involving different perforating guns. The results suggested that the proposed monitoring method is able to monitor perforating guns of different shaped charges with a perforating depth between 500m-3500m and in oil wells with an inclination of 0° - 90°. As a means of vibration detection, this method also works well in other types of vibration monitoring.

This paper proposes a method for detecting the vibration of subsea spanning pipelines by using a spherical detector (SD) equipped with a triaxial accelerometer. The mathematical analyses and experiments demonstrate that the acceleration modulus square (AMS) and the AMS of the ac components (AMS_AC) of the acceleration signals recorded by the SD have one characteristic component whose frequency is equal to and can be used to determine the pipeline vibration frequency. As the amplitude of this component is immune to the rotation noises of the SD, its signal-to-noise ratio is higher than that of other components whose frequencies are the mixture of the vibration and rotation frequencies. Removing the dc bias along the three sensitive axes can eliminate other characteristic frequencies to make the AMS_AC having the unique frequency to indicate the pipeline vibration. The vibration frequency can be accurately and sensitively identified by using the AMS_AC. The detection thresholds of 5-, 10-, and 15-Hz vibrations are 0.6, 0.4, and 0.2 mm with regard to the amplitude, respectively.