| By the development of oilfield, the quantity of casing-damaged wells increases year by year. There are about 700-800 casing damaged wells exist in Daqing every year, they have severely influenced the conventional development of the oilfield. Due to the regional and directional characteristics of casing damage, accurate inspections on damage azimuth and degree are getting more and more important. The caliper tools are mainly used as inspecting way for casing damage domestic and abroad at present, but they can not meet the needs for casing damage inspection and prediction due to the bigger O.D, fewer measuring arms, poor performance through damaged location, limited gained information, significant shifting on transducer measurement and low accuracy.This paper studies the azimuth caliper combination tool, which combines an azimuth logging tool with a 20-arm caliper for slim wells. It's a reliable logging tool with good passing property and high accuracy.The azimuth logging tool consists of a flexible gyro, a frame gyro and three accelerometers. The stational measurements of inclination angle, azimuth angle and direction angle are achieved by the combination of flexible gyro and three accelerometers; the stable measurements of them are achieved by the combination of frame gyro and three accelerometers. The initial azimuth of frame gyro is initialized by stational azimuth measurement of flexible gyro without the shifting effect of frame gyro. So the combination tool can accomplish the measurement of wellbore track with reliable properties and high accuracy without time shifting. It's also an ancillary joint, which provides the information of direction angle, wellbore inclination angle and azimuth angle for other engineering logging tools.The slim 20-arm caliper is a contact mechanical caliper with a high accurate differential displacement transformer as displacement transducer. When logged up, the radial change happens with the change of casing through a cam transfer, hence the vertical displacement change of displacement transducer happens.The downhole circuits acquire, transfer, code, drive the signals from 20 transducers. Finally, the surface acquisition gains quick-look 3D map, colored plain map and cross-sectional profile map after the treatment of image system.During the study of logging method and data processing azimuth and caliper combination, there are mainly three aspects of creation.1. It's the first time that frame gyro and flexible gyro are combined together in domestic and overseas wellbore track inspection. It realizes and improves the inspection accuracy of azimuth serial information.2. The azimuth calculation model is constructed, and the azimuth caliper software including azimuth calculation software is developed. It realizes the automatic azimuth interpretation algorithms calibration..3. It's the first time that azimuth technology is combined with multi-arm caliper technology. It can present the geological azimuth of casing damage, which is useful for casing damage mechanism analysis. It obtains the instructive meaning for the prediction of casing damage.After several years of field application, the azimuth caliper combination tool has been applied in more than 300 wells with the output value of 10 million RMB. Field result shows the combination tool can provide different degrees and different types of casing damage and their locations in a vivid and detailed way. It can inspect the situation of downhole casing damage in oilfield accurately. It can meet the needs of casing damage inspection and prediction and provide the basis for casing damage prediction, workover, abandonment and casing damage mechanism analysis in production wells. It can effectively protect the casing and prevent the happening of casing damage. It can reliably instruct and inspect the treatment and mending for recovering the production capacity of casing damaged wells. It plays significant role for oilfield stabilization and development.
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