On Azimuth Observability During INS Alignment in Horizontal Drilling

Efraim Pecht and Martin P. Mintchev

Abstract:	Horizontal directional drilling (HDD) has a significant impact on improving oil and gas exploration and extraction. Long-term HDD performance and accuracy are directly related to high-quality navigation capabilities. Currently, HDD navigation incorporates magnetometers which provide azimuth angle readings based on the Earth magnetic field. However, due to magnetometer susceptibility to magnetic interferences, the accuracy of this technique is limited. Introduction of inertial navigation systems (INS) in above-ground navigation motivated researching new avenues for magnetometer replacement in horizontal drilling. Previous research has showed that direct application of INS downhole has longterm limitations, predominantly due to the growing error in the azimuth angle. The proposed In-Drilling Alignment (IDA) is a method that can significantly reduce this cumulative azimuth angle error, thus facilitating INS applicability in horizontal drilling. The IDA concept takes advantage of options available during the HDD process by introducing controlled motion patterns in a predesigned space. Using this technique the INS observability can be significantly improved, resulting in reduced state error.
Published in:	Proceedings of the 2005 National Technical Meeting of The Institute of Navigation January 24 - 26, 2005 The Catamaran Resort Hotel San Diego, CA
Pages:	276 - 281
Cite this article:	Pecht, Efraim, Mintchev, Martin P., "On Azimuth Observability During INS Alignment in Horizontal Drilling," Proceedings of the 2005 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2005, pp. 276-281.
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