Docs and Publications

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Error Model Management Sub-committee short cut
SPE 56702, "Accuracy Prediction for Directional MWD." Hugh Williamson - BP Amoco: SPE Annual Technical Conference, Houston, Texas, 3-6 (Oct-1999)
Note: This was the original version of the MWD error model and has been updated as SPE 67616 below.

SPE 67616, "Accuracy Prediction for Directional Measurement While Drilling." Hugh S. Williamson: SPEDC Dec 2000, SPE Drilling & Completion Vol 15 No.4 December 2000 page 221-233

Note: This is an updated version of the MWD error model paper (SPE 56702) and was published in SPE Drilling and Completion and has been designated as SPE 67616.
See for further corrections to this paper.

SPE 90408, "Prediction of Wellbore Position Accuracy When Surveyed With Gyroscopic Tools." Torgeir Torkildson (Statoil), Stein T. Havarstein (Statoil), John L. Weston (Halliburton), Roger Ekseth (Gyrodata): SPE Annual Technical Conference and Exhibition, Houston, 26-29 (Sep-2004)
Note: This paper contains the gyro survey tool error model.

SPE 95611, "Quantification of Depth Accuracy." A. Brooks, SPE, and H. Wilson, SPE, INTEQ; A. Jamieson, SPE, Tech 21; D. McRobbie, SPE, Sperry Drilling Services; and S.G. Holehouse, SPE, Total S.A.: SPE Annual Technical Conference, Dallas, 9-12 (Oct-2005)
Note: This paper summarises depth issues.

IADC/SPE 103734, "The Reliability Problem Related to Directional Survey Data." Roger Ekseth, Kazimir Kovalenko, J.L. Weston (Gyrodata Inc), Torgeir Torkildsen, Erik Nyrnes (Statoil ASA), Andrew Brooks and Harry Wilson (Baker Hughes Inteq): IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, 13-15 (Nov-2006)
Note: This paper lists all sources of error, describes internal data checks that are capable of identifying many of them, and highlights those that are missed and which will therefore require alternative QC measures. Real wellbore survey data are used to illustrate how the use of inadequate QC procedures can lead to invalid survey data being accepted as valid.

SPE/IADC 105558,"High-Integrity Wellbore Surveys: Methods for Eliminating Gross Errors." Roger Ekseth (Gyrodata); Torgeir Torkildsen (Statoil ASA); Andrew Brooks (Baker Hughes Inteq); John Weston (Gyrodata); Erik Nyrnes (Statoil ASA); Harry Wilson (Baker Hughes INTEQ) and Kazimir Kovalenko (Gyrodata): SPE / IADC Drilling Conference, Amsterdam, The Netherlands, 20-22 (Feb 2007)
Note: This paper follows on from IADC/SPE 103734 and proposes a new set of minimum requirements for survey validation, which, in general, incorporate the need for an overlapping verification survey or other independent observation (External data checks).

ISCWSA Error Model Reference Documents

Details and corrections to SPE 67616 are in the following document:

MWD Error Model Rev.3 ISCWSA_MWD_Error_Model_Revisions

British Geological Survey Global Geomagnetic Model (BGGM) Uncertainties
From the BGS Geomagnetism webpage:
"Recent work on determining the accuracy of the BGGM (compared to "clean" downhole magnetometer measurements unadjusted for the local crustal fields and time-varying external fields) is reported in SPE paper 119851. The associated confidence limit files are available to
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