SPE Drilling & Completion
Volume 27, Number 3, September 2012, pp. 363-367

Summary

The commonly used technology in well-trajectory logging, for both the oil and the gas well, is the magnetometer. However, it cannot work well in the magnetic-interfered or nonmagnetic environment, such as in a cased well or an iron mine. This paper presents a new trajectory-logging tool with a small diameter. Configured by a three-axis FOG unit and three quartz accelerometers, the logging tool allows for continuous attitude and trajectory measurement. High-temperature-caused accuracy degradation is the major error source for the underground environment. To diminish the thermal-related error, a flask stuffed with thermal-insulation material was embedded in the tool body; meanwhile, a wavelet neural network was used for identification of and compensation for the temperature drift. The system configuration, trajectory-resolution algorithm, and temperature-compensation algorithm are presented in this paper. Testing results show that the inclination accuracy is better than ±0.1°, with a range of 0 to 180°, and the azimuth accuracy is better than ±2°, with a range of 0 to 360°. The new logging tool resolves continuous trajectory-measurement problems in a magnetic-interfered or a nonmagnetic environment. Moreover, the capability of all-attitude measuring facilitates horizontal-well logging. Therefore, broad applications and good marketing could be anticipated for this new logging tool.

© 2012. Society of Petroleum Engineers

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History

• Original manuscript received: 27 December 2011
• Revised manuscript received: 14 March 2012
• Manuscript approved: 28 March 2012
• Published online: 29 August 2012
• Version of record: 18 September 2012