Multi-station azimuth correction

This article focuses on the Novel MSA correction implemented in our commercial platform, MWD STD Advanced. But we also have free solutions that use the industry standard MSA: the automated cloud platform MWD STD Basic and the standalone application MWD STD MSA.

MWD tools measure azimuth with respect to the local magnetic field. So all magnetic surveys are subject to magnetic interference from different sources. The major source of interference is drillstring¹. The common practice to compensate for that error is utilizing of the multi-station analysis (MSA) for azimuthal correction^{2, 3}. However, conventional MSA can lead collision avoidance and target intersection issues³ due internal fundamental accuracy restrictions or misusing of the algorithm⁴.

MSA correction stability case study: The red line is the horizontal displacement of the trajectory calculated while drilling using the conventional MSA correction, the trajectory drifted due to MSA instability. The blue line is the output of the novel MSA.

MWD STD platform is empowered by the industry most accurate and robust novel MSA algorithm for MWD survey correction⁵. That algorithm utilizes all available drilling information to provide the best accuracy: BHA design, slide sheets, geomagnetic references, D&I error model, entire 6-axis surveys, etc. Unlike the conventional MSA, the novel algorithm does not have no-go zone at horizontal east-west directionsб under nominal conditions. Also, additional input information ensures much higher robustness and reliability that is critical for survey processing automation.

MSA performance comparison. Red ellipse – conventional MSA; green one – the novel algorithm

_{1. Williamson, H.S.: “Accuracy Prediction for Directional Measurement While Drilling”. Paper SPE 67616, SPE Drilling and Completion 15 (4), December 2000}

_{2. Brooks, A.G., Gurden, P.A., Noy, K.A.: “Practical Application of a Multiple-Survey Magnetic Correction Algorithm”, SPE 49060, September 1998}

_{3. Hanak, C., Wilson, H., Gjertsen, M.: “Assessment of the Validity of MWD Survey Accuracy Following Multistation Analysis”, SPE/IADC 173098, March 2015}

_{4. Nyrnes, E., Torkildsen, T., Wilson, H.: “Minimum requirements for multi-station analysis of MWD magnetic directional surveys”, SPE/IADC 125677, October 2009}

_5. _{Bulychenkov, Konstantin. “Overcoming Fundamental Restrictions: Novel Multistation Measurement While Drilling Survey Correction.” SPE J. (2022;): doi: https://doi.org/10.2118/210084-PA}