ISCWSA Sub-Committees


Mission Statement - Develop and describe good practice in collision avoidance management, and promote its adoption in the well construction industry.

The work group has produced several documents which are revised periodically and are available on this site (see "Collision Avoidance Docs and Publications").
Please contact the Sub-Committee chair Steve Sawaryn if you would like to contribute to, or join the Collision Avoidance Work Group.

Collision Avoidance Sub-Committee Docs and Publications

Download Last Minutes of Meeting

Previous meetings:
Minutes of the 17th meeting, and work group document links below, Amsterdam, Holland 31-10-2014
No minutes published for the 16th meeting
Minutes of the 15th meeting, New Orleans USA 02-Oct-2013
Minutes of the 14th meeting, Paris, France 07-Mar-2013
Minutes of the 13th meeting, San Antonio, Texas, USA 10-Oct-2012
Minutes of the 12th meeting, Edinburgh, Scotland, UK, 9-May-2012
Minutes of the 11th meeting, Denver Colorado, USA, 3-Nov-2011
Minutes of the 10th Meeting, Copenhagen, Denmark, 3-Mar-2011
Minutes of the 9th Meeting, Florence, Italy, 22-Sep-2010
Minutes of the 8th Meeting, Austin, USA, 2-Mar-2010
Minutes of the 7th Meeting, New Orleans, USA, 7-Oct-2009
Minutes of the 6th Meeting, Amsterdam, The Netherlands, 19-Mar-2009
Minutes of the 5th Meeting, Denver, USA, 24-Sep-2008
Minutes of the 4th Meeting, Inverness, Scotland, 22-Apr-2008
Minutes of the 3rd Meeting, Anaheim, USA, 14-Nov-2007
Minutes of the 2nd Meeting, Rijswijk, The Netherlands, 22-Feb-2007
Minutes of the 1st Meeting, San Antonio, USA, 27-Sep-2006

Mission Statement - Since inception the sub-committee has been primarily focused on organizing SPE Applied Technology Workshops as a method of raising awareness of wellbore positioning issues to the broader industry. The workshop “Collision Avoidance and Wellbore Interceptions – Hits and Misses” has now been presented three times. The first was held in Inverness Scotland followed by Denver Colorado and most recently in Istanbul Turkey. With the exception of Istanbul, which came close, all sold out. The workshop will be repeated again in 2015, November 9th-11th at the San Luis resort in Galveston Texas. The workshop content has been updated and expanded and is now titled, “Well Placement Best Practice for Increasing Value and Reducing Consequence”. Time will tell if this is the end of the road or we will run it again in another location.

Recently it was agreed by the larger membership that the Education Sub should take editorial control for updates and expansion of the Joint Industry Project e-book “Introduction to Wellbore Positioning”. We are currently in process of adding several new chapters to the book, they should be available later this year. The ISCWSA wellbore surveying, on-line competency course is now open for registration. Just to let you all know, the website is live. You can watch the promotional video there and see the course details. It is an introduction to the workings of a typical drilling rig and a quick tour of a working rig site.

Education Sub-Committee Meeting Minutes

You can download the Joint Industry Project e-book "Introduction to wellbore positioning" here

Surveying Summary Video

You can download the recently released FREE "ISCWSA: WELL INTERCEPT SUB-COMMITTEE EBOOK" here

Click here to play the 2018 recording of the SPE Webinar wellbore-ranging-technologies-intercept-applications-and-best-practices

If you are interested in joining the Education Sub-committee please contact the chair, Carol Mann

Join the Error Model Sub-committee by contacting Andy McGregor.

The role of the ISCWSA Error Model Maintenance Group is to define the mathematical framework for modelling the uncertainty in wellbore surveying. This allows different companies to implement a consistent set of algorithms for error modelling.

In general, the ISCWSA does not define or supply the detailed magnitudes (or error models, tool codes or IPM files) for a particular survey tool. It is our position that the tool provider is the one who is best placed to assess the uncertainty when using their equipment. Therefore users should request tool codes from their tool provider.

The ISCWSA does not supply, check, certify or warrant the error models created by tool providers. However, the ISCWSA has specified a generic MWD tool error model. It comes in eight variants for the various combinations of:
i) standard MWD or axially (short collar) corrected surveys
ii) from a fixed or floating platform
iii) with or without sag correction

There have been several revisions of these models and we are now at Rev4 05Jun 2015, details of the ISCWSA MWD Error Models up to Rev4 05Jun 2015.

The fact that the ISCWSA provides these does not mean that users are forced to use them, that ISCWSA has defined minimum survey requirements, or that tools must be run in this manner. The principle is that any error model applied should correctly match how the tool was used and how it can be expected to perform.

These are generic tool codes and it is up to users and tool providers to ensure that these models correctly match their situation. Like any error model, the generic MWD model makes several assumptions about tool spec, running procedures and processing standards that must be met for the model to be valid for its application to any particular survey log.

As a separate initiative, the Operators Survey Work Group (OWSG) provides a more complete set of tool codes covering many wellbore survey situations (link). These make use of the mathematical framework defined by the ISCWSA Error Model Group and at Rev2 the OWSG set includes the latest ISCWSA MWD Rev4 models. The OWSG models are simply offered as one possible set of models that are compliant with the ISCWSA framework and are neither formally endorsed nor approved by the ISCWSA Error Model group.

Recommendations for management of inclination_Rev1D

Meeting minutes from the ISCWSA#47 meeting in Inverness, Scotland UK 10Apr 2018

Meeting minutes from the ISCWSA#46 meeting in San Antonio, Texas 11Oct 2017

Definition of ISCWSA Error Model_Rev4
- Error_Model_Example_MWDRev4_ISCWSA_1
- Error_Model_Example_MWDRev4_ISCWSA_2
- Error_Model_Example_MWDRev4_ISCWSA_3

Meeting minutes from the ISCWSA#45 meeting not published

Meeting minutes from the ISCWSA#44 meeting in Glasgow 21Sept 2016

Meeting minutes from the ISCWSA#43 meeting in Fort Worth 4Mar 2016

Meeting documents released from the ISCWSA #42 meeting in Houston 02Oct 2015

Meeting minutes and documents released from the ISCWSA #41 meeting in London 20 Mar 2015


Meeting minutes from the ISCWSA #40 meeting in Amsterdam 29 Oct 2014

MWD Error Model Revisions
The current version of the MWD Error Model is Revision 3.
Further details and corrections to SPE 67616 are in the following document:


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 download."

The paper, SPE/IADC 119851 'Confidence Limits Associated with Values of the Earth's Magnetic Field used for Directional Drilling', described updated uncertainties for use with predicted geomagnetic parameters from the BGGM.
Copies of the paper SPE/IADC 119851 'Confidence Limits Associated with Values of the Earth's Magnetic Field used for Directional Drilling' by Susan Macmillan, British Geological Survey; Allan McKay, Petroleum GeoServices; Steve Grindrod, SPE, Copsegrove Developments Ltd, at the SPE/IADC Drilling Conference in Amsterdam 2009, are available from the SPE.
The results of the study included look-up tables arranged by geographic latitude and longitude for each confidence level. The associated confidence limit tables are available in the files below:
The ISCWSA Error Model Management Sub-Committee was set up to maintain and develop the error models.
The Sub-Committee has been tasked with revising the MWD and Gyro papers to improve implementation and make them more accessible.

More information on the Error model Sub-Committee may be obtained from the Sub-Committee chairman; Andy McGregor
Further reading and work on the ISCWSA format Error Model please see the following website:

Mission Statement: To promote practices that provide confidence that reported wellbore positions are within their stated uncertainty.

Please contact OWSG Chair Person Pete Clark if you would like to participate in the Operator Wellbore Survey Sub-Committee.

Extract from 24 Jan 2018 meeting:

Specification spreadsheets for sets A & B are available at
Diagnostic files for both seat A and B are available at

15 OWSG Meeting Minutes 24 Jan 2018
14 OWSG Meeting Minutes 15 Mar 2017
13_OWSG Meeting Minutes 20 Sep 2016
12_OWSG Meeting Minutes 02 Mar 2016
11 OWSG Presentation Son Pham
10_BP OWSG Meeting 20 Mar 2014 No minutes

9 OWSG Meeting Minutes 23 Jan 2014
8 ISCWSA NOLA N Bergstrom_OWSG_Report_Recommendations
OWSG Meeting Minutes 10 Mar 2013
7 Chevron OWSG_Meeting_Minutes 27 Jun 2013
6 Talisman OWSG_Meeting_Minutes 3 Apr 2013
5 Shell OWSG_Meeting_Minutes 23 Jan 2013
4 BP OWSG Meeting Minutes 5 Dec 2012
3 ConocoPhillips OWSG Meeting Minute 16 Aug 2012
2 Chevron OWSG Meeting 06 Jun 2012 No minutes

1 Devon OWSG Meeting 02 Apr 2012 No minutes


Mission statement - Develop good practice in well intercept scenarios and promote its adoption in the well construction industry.

The SPE Wellbore Positioning Technical Section are proud to announce the release of the ISCWSA: WELL INTERCEPT SUBCOMMITTEE EBOOK ver10.4.12

Please contact the Chair Roger Goobie: if you would like to contribute to the ISCWSA Well Intercept Sub-committee.

Click here to play the 2018 recording of the SPE Webinar wellbore-ranging-technologies-intercept-applications-and-best-practices

Well Intercept Minutes 07Mar 2013

Well Intercept minutes Minutes 08May 2014

Work Group Project Docs:
Bibliography - Completed 2017
Lexicon finished to be published 2016 - Completed 2017
Ranging Section to be added to the ISCWSA e-book - Completed 2017
Best Practice
- Completed 2017

Mission Statement:

To define practices that promote the task of defining the required data which may be used to validate and potentially enhance a
wellbores' position and uncertainty.

This sub-committee has taken on a new project to Define and Communicate the Essential Data Required to Verify and Potentially Enhance a Wellbore.

This Sub-Committee has prepared two SPE Papers on survey quality control procedures that are required to ensure a valid error model is applied to the survey data.

SPE 103734 is on ‘Internal’ survey quality checks and was presented at the IADC/SPE Asia Pacific Drilling Technology Conference, Bangkok in November 2006.

SPE 105558 is on ‘External’ survey quality checks and was presented at the SPE/IADC Drilling Conference and Exhibition, Amsterdam in February 2007.