© Copyright 2006 POSC Coordinate Reference Systems John Bobbitt & Paul Maton June 2006

© Copyright 2006 POSC WITSML Change to support CRS and Geodetics High level overview of the change A quick look at the XML A quick look at the CRS registry.

© Copyright 2006 POSC General Principles Every location needs a CRS. Some CRSs exist independent of a well – some don’t Standard CRSs can be in a library, and only need to be referenced. The standard CRSs include geographic, projected, and vertical. Use standard systems; e.g., EPSG systems.

Shell Exploration & Production WITSML workshop Paris, 3 November 2004 – Slide 4 Same latitude & longitude: different Geodetic Datums WGS84 ED50 OSGB36 x x x x x x 100 metres Locations with same ellipsoidal coordinate values

© Copyright 2006 POSC Approved Change - 1 A location will reference a CRS as defined in well. Each well object will reference/define a set of CRSs. –Local (engineering) will be defined within a well object –Geographic, projected, and standard vertical will be referenced in the well object. A new “crs” object will be developed to handle the standard systems. –When a standard system is used, it will be referenced. –When a non-standard system is used, it will be defined. Already there New Addition Modified

© Copyright 2006 POSC Approved Change - 2 A library of EPSG coordinate reference systems will be available –Accessible by EPSG code –Returned in GMLReturned in GML Non-standard systems may be defined in GML

© Copyright 2006 POSC XML Example - location ED50 / UTM Zone 31N Location of well surface point in projected system. References a CRS with uid=‘proj1’

© Copyright 2006 POSC 6507/7-A ED50 ED50 / UTM Zone 31N Well One WSP... Definition of local CRS follows... XML Example - well Here’s how a location references a system This references a definition in a crs object

© Copyright 2006 POSC ED50 European Datum 1950 ED50 / UTM Zone 31N ED50 / UTM Zone 31N XML Example - CRS Well referenced these values These reference standard CRS: EPSG v6.8 Code = 4230 These reference standard CRS: EPSG v6.8 Code = 23031

© Copyright 2006 POSC Review of Changes Continue having a location reference a CRS –The CRS is in the well object, under wellCRS –No change from present The well object references a CRS, or defines a local CRS. The “CRS” object either defines the CRS or references a service that defines it. The CRS definition uses GML.

© Copyright 2006 POSC What about vertical? We have simplified the ISO/OGC capability that allows a 3D system –We always separate horizontal from vertical The vertical reference has already been implemented in WITSML –Change: We will allow a standard vertical system to be referenced.

© Copyright 2006 POSC Library of CRSs POSC has a library of EPSG CRSs developed on GML and 3.2 – oid.xmlhttp:// oid.xml Galdos (and others?) are developing services that can return the same information.

© Copyright 2006 POSC Next Steps Proposal from Work Group has been accepted by WITSML Technical Team Organized for inclusion in next WITSML release Given member interest, we are prepared to –conduct implementation/use orientation and training sessions, –coordinate preparation of written usage guidelines, and –facilitate a CRS/Geodetics user work group

© Copyright 2006 POSC Thank You!