The borehole televiewer operates with pulsed acoustic energy so that it can image the borehole wall in the presence of opaque drilling muds. Short bursts of acoustic energy are emitted by a rotating transducer in pulse-echo mode. These travel through the drilling mud and undergo partial reflection at the borehole wall. Reflected pulses are received by the transducer. The amplitudes of the reflected pulses form the basis of the acoustic image of the borehole wall. These amplitudes are governed by several factors. The first is the shape of the borehole wall itself: irregularities cause the reflected energy to scatter so that a weaker reflected signal is received by the transducer. Examples of these irregularities are fractures, vugs, and breakouts. Moreover, the reflected signal is degraded in elliptical and oval wellbores because of non-normal incidence. The second factor is the contrast in acoustic impedance between the drilling mud and the material that makes up the borehole wall. Acoustic impedance provides an acoustic measure of the relative firmness of the formations penetrated by the wellbore material and, thus, it has the capability of discriminating between different lithologies, with high acoustic impedance giving rise to high reflected amplitudes. Borehole televiewers work best where the borehole walls are smooth and the contrast in acoustic impedance is high. The third factor is the scattering or absorption of acoustic energy by particles in the drilling mud. This problem is more serious in heavily weighted muds, which are the most opaque acoustically, and it gives rise to a loss of image resolution.
The borehole televiewer can provide a 360 degree image in open or cased holes. It can operate in all downhole environments other than gas-filled holes. The travel time for the acoustic pulse depends on the distance between the transducer and the borehole wall, as well as the mud velocity. Modern televiewers allow some independent method of measuring the mud velocity. Thus, the borehole televiewer also operates as an acoustic caliper log. For best results, the tool should be centered, although correction algorithms have been developed for eccentered surveys.
It is suitable for such engineering fields as engineering geology, hydrological geology, geotechnical engineering inspection and monitoring. It is suitable for various boreholes including vertical borehole, horizontal borehole, anchor cable (rod) borehole, geological borehole and concrete borehole. It can form digital borehole core sample for permanent preservation, especially suitable for the crushing zone strata where actual core samples cannot be obtained. 1.Perform full-hole wall imaging and video recording on the core hole of the pile foundation, capture the picture at key parts, etc.
2. Observe and measure the thickness and orientation of the interlayer in the pile;
3. Observe and measure the depth position and fracture of the broken pile The width of the orientation.
1. High integration: highly integrated system control, image acquisition, display and storage in the controller;
2. High intelligence: The controller has a built-in dual-core processor with an image processing speed of 25 frames per second. At the same time, the image data, the depth data and the spatial data of the position of the probe are obtained, which can ensure the real-time automatic acquisition of the panoramic image, fast and seamless splicing, automatic angle and depth correction, and the panoramic video image is presented in real time, and the image is clear and realistic. Synchronize image stitching, recording and screenshots;
3. High reliability: The whole system is highly integrated and has good stability; the instrument is sealed, waterproof and dustproof;
4. High definition: The camera is color low illumination 700Lines, 0.1L1.x, 1.3 million pixels; the intensity of the light source can be continuously adjusted to ensure clear imaging of various detection objects;
5. Wide viewing angle: The camera has a wide viewing angle, which can realize horizontal 360-degree panoramic imaging without focusing;
6. Good portability: The whole machine is small in size, light in weight and easy to carry;
7. Good operability: The whole system is simple to connect, easy to operate, and the first-time user can get started quickly; the host can be used as an external USB flash drive of the computer, and the data can be directly copied and pasted;
8. Low power requirements: The host has built-in high-capacity lithium battery power supply, and the continuous working time is not less than 10 hours;
9. Three types of display flexible switching: the analysis software can display and output the plane expansion map, the stereoscopic histogram, the stereoscopic histogram can be rotated 360 degrees continuously; the core description result table and the core histogram and the expansion map can also be displayed in the same width;
10. Direct core description: The core can be directly described on the unfolded map. The inclination, inclination and width of the crack can be directly calculated and extracted automatically. The width accuracy can reach 0.1mm and the azimuth angle can reach 0.1 degree.