# Appendix D – Error Model Description

The error model implemented in Well Seeker is the ISCWSA MWD error model as described in SPE paper 67616 by H. Williamson. This paper contains a full explanation of the ISCWSA work. The error model used within this program uses the error terms and one sigma magnitudes described below.

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The model does not use any bias terms and it implements the latest misalignment and tool face independent terms as listed below.

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![](https://100379801-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-McEwHTOM_v4MexTVGSe%2F-MhYc0lNVDUH-sFRmZG6%2F-MhYc9UkPdU8XwIoRCju%2F17.PNG?alt=media\&token=1abb9589-53e3-4197-83a4-b2f3e6523852)

![](https://100379801-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-McEwHTOM_v4MexTVGSe%2F-MhYc0lNVDUH-sFRmZG6%2F-MhYcND_v46sGMhMW6M9%2F18.PNG?alt=media\&token=4025f15c-1d01-46e3-8d0f-f2cdcb4c13db)

Misalignment terms taken from SPE90408 by Torkildsen, Ekseth, Weston, Havardstein and TF independent terms from “Borehole survey error model documentation” – CDR-SM-03 – by Copsegrove Developments.