Experts in Geomatics, Surveying, Positioning, Geospatial Data, and Mapping Sciences PPDM Data Management Symposium March 7, 2012 Houston Michael Barnes APSG Foundation Chair 2010-2015 APSG Chair 2008-2009 PPDM HOUSTON 2012 1
Experts in Geomatics, Surveying, Positioning, Geospatial Data, and Mapping Sciences Geodetic Integrity: The Essential Basics for Data Managers and Users Michael Barnes Cain & Barnes LP The Geomatic Experts Group PPDM HOUSTON 2012 2
Data Tools Zone of the Geodetic Quagmire Knowledge Techniques PPDM HOUSTON 2012 3
Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software Knowledge Basic Geography College, University Industry Training Learning & Development Geodetic Integrity Techniques Standards & Practices Procedures & Workflows Quality Control Processes Continuous Improvement PPDM HOUSTON 2012 4
Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval Tools Project Work Knowledge Techniques PPDM HOUSTON 2012 5
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Source: OGP PPDM HOUSTON 2012 7
Source: OGP PPDM HOUSTON 2012 8
80% + of all GG&E data Units of Measure stated? e.g. US Survey Foot International Foot Metre, etc Mandatory Metadata PPDM HOUSTON 2012 9
Commercial Well Location Data PPDM HOUSTON 2012 Source: APSG 10
Commercial Digital Land Grids PPDM HOUSTON 2012 Source: APSG 11
Area Discrepancy due to Incorrect Grid PPDM HOUSTON 2012 12
Example Unit with Discrepancies Measured PPDM HOUSTON 2012 13
Various State & Vendor Database Well Locations PPDM HOUSTON 2012 14
Source: Conner PPDM HOUSTON 2012 15
Source: Conner PPDM HOUSTON 2012 16
Libya Well Location Database Satellite Imaging Corporation PPDM HOUSTON 2012 17
Potential Causes of Well Positioning Errors Why are the wells plotted at incorrect locations in the previous Libyan example? Possibly some have used the wrong geodetic datum Or incorrect datum transformations to WGS 84 were used Perhaps some were plotted from pre-plot locations Different positioning technologies over many years The mis-positioning here is probably from a number of different causes as the errors are of varying magnitudes and in different directions PPDM HOUSTON 2012 18
Forensic Geodetics of One Well Location (US GOM) Cost of well was Followed the data from G&G through Drilling Ops 486 documents with location (x,y) 40% had no datum stated NAD 27, NAD 83, WGS 84 datums are all relevant for this process In UTM grid, positioning difference is? PPDM HOUSTON 2012 19
Ignoring Geodetic Datums for a Single Well Position in the Central Gulf of Mexico NAD 83 NAD 83 datum Lat. 27º 00 37.49 N Long. 92º 14 10.97 W N NAD 27 minus NAD 83: Latitude = -1.02 Longitude = -0.31 NAD 27 NAD 27 datum Lat. 27º 00 36.47 N Long. 92º 14 10.66 W PPDM HOUSTON 2012 20
Different Datums for a Single Well Position in the Central Gulf of Mexico N NAD 83 199 m or 652 ft NAD 27 NAD 83 datum Lat. 27º 00 37.49 N Long. 92º 14 10.97 W NAD 27 minus NAD 83: Latitude = -1.02 Longitude = -0.31 UTM Zone 15N Northing = -198.57 m (-651.47 ftus) Easting = + 10.19 m NAD 27 datum Lat. 27º 00 36.47 N Long. 92º 14 10.66 W (33.44 ftus) PPDM HOUSTON 2012 21
Russia Land Seismic in the Wrong Map Projection 950m errors Example courtesy of Satellite Imaging Corporation PPDM HOUSTON 2012 22
Geodesy: Essentials for Geospatial Data Geodetic Datum Map Projection Vertical Orientation Unit of Measure PPDM HOUSTON 2012 23
Geodesy 101 Geodetic Datum Map Projection Vertical Orientation Unit of Measure Coordinate Reference System Grid, X and Y Elevation, Height, Depth North, Direction Foot or Meter PPDM HOUSTON 2012 24
Geodetic Reference Surfaces h H N Normal to Ellipsoid Normal to Geoid N=h-H Ellipsoid Geoid Terrain b a Geoid Equipotential surface which approximates to MSL PPDM HOUSTON 2012 Ellipsoid Surface where Computations are made 1/f = a/(a-b) Source: APSG 25
The one thing you need to know about a Geodetic Datum is.. YOU NEED ONE PPDM HOUSTON 2012 26
Geodetic Terminology (ISO compliant) Topography / Terrain (= actual earth surface) Geoid (= equipotential earth s surface ~ MSL) Ellipsoid / Spheroid = Mathematical figure used for computations Coordinate System (only a system of axes in ISO) Prime Meridian (the meridian that is set to zero for a given datum) Geodetic Datum Local / Astrogeodetic Datums Geocentric Datums / Global Datums Ellipsoid and Datum are NOT synonyms! Assuming otherwise can lead to costly mistakes PPDM HOUSTON 2012 27
Prime Meridian = 0 degree longitude PPDM HOUSTON 2012 28
Major World Datum Blocks North America European Pulkovo Indian Tokyo South America Cape Arc Australian Pulkovo Over 350 well-defined Horizontal Datums worldwide! Tokyo Beijing 54 JGD2000 Iwo Jima 45 Xian 1980 Herat Hu Tzu Shan Kalianpur Indian 37 54 Hong Samboja Kong Kalianpur India Hanoi VN2000 Luzon 62 Kerta Kandawala n 60 Timbalai u Batavia Bukit DGN9 Rimpah ID74 Gan 1970 DGN9 5 5 AGD66 AGD84 GDA2000 PPDM HOUSTON 2012 29
Geodetic Datum Examples Datum Origin PLUS Reference Ellipsoid = Datum 11 main stations + Airy = OSGB36 Many points (global) + WGS72 ellipsoid = WGS72 1591+ points (global) + WGS84 ellipsoid = WGS84 Potsdam + International 1924 = ED50 La Canoa, Venezuela + International 1924 = PSAD56 Meade's Ranch, KS + Clarke 1866 = NAD27 Many pts, North America + GRS80 = NAD83 Herstmonceaux, UK + Airy = OS(SN)80 Manoca Twr, Cameroon + Clarke 1880 IGN = Manoca Minna Station, Nigeria + Clarke 1880 RGS = Minna Many points (global) + GRS80 = ITRF yyyy Where yyyy is adj. year PPDM HOUSTON 2012 30
Hierarchy of Geospatial Data or Mapping Ellipsoid hp P stable Unstable w/o Datum λp Equator Yp Φp Zp Xp Map Projection is a derivative of the Datum Easting, Northing, X,Y Elevation (above MSL) Geodetic Datum (includes ellipsoid) is the Foundation X,Y,Z Cartesian and Lat Long, Ht PPDM HOUSTON 2012 Source: APSG 31
Remember... Knowing the map projection and all its parameters is insufficient (even if the ellipsoid is known)! Unless associated with a Geodetic Datum The Map Projection coupled with a Geodetic Datum makes a Projected Coordinate Reference System (or ProjCRS) PPDM HOUSTON 2012 32
Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software Knowledge Basic Geography College, University Industry Training Project Work Techniques Standards & Practices Procedures & Workflows Quality Control Processes Learning & Development Continuous Improvement PPDM HOUSTON 2012 33
Coordinate Formats and Precision Ellipsoid NP Parallels Software Convention: N,E (+); S,W (-) 0 Longitude (λ) - 180 0 180 Equator Meridians Latitude ( ) - 90 0 90 Precisions shown consistent to centimeter level Degrees Minutes Seconds (DD MM SS.sss H) 34 27' 17.453" N 118 31' 32.684" E Degrees Decimal Minutes (DD MM.mmmmm H) 34 27. 29088' N 118 31. 54473 E Decimal Degrees * (DD.ddddddd H) 34.2881814 N 118.5257456 E DMS in Sexigesimal Format (DD.MMSSssss) 34.2717453 N 118.3132684 E * difference is about 20 kilometers (12 statute miles) if DD.MMSSsss thought in DD.ddddddd format! PPDM HOUSTON 2012 34
Coordinate Transformations are not trivial PPDM HOUSTON 2012 Source: OGP EPSG Registry 35
More Confusion in Geodesy Reference Orientations: (5 types of North) True North = direction of the meridian through a point Magnetic North = differs from True N by Declination Grid North = differs from True North by convergence Gyro North = a measurement of True North by instrument Plant North = strictly a local non-georeferenced orientation PPDM HOUSTON 2012 36
Magnetic Declination Montana 45N, 112W on Jan 18, 2004 14.35º E changing by 6' West per year Brazil (Campos) 23S, 41W on Feb 24, 2004 22.4º E changing by 6' East per year PPDM HOUSTON 2012 37
Downhole Surveys: Varying North References Orientation From various well documents and databases Casing MWD: Magnetic (referenced to Magnetic North) Below Casing: Inertial (referenced to True North) Rig orientation: (referenced to Grid N or True N?) When data are merged: Was the magnetic data adjusted to grid or true N? Has the rig orientation used the same North reference? Is all this documented for other departments / users? Do specifications lead to consistent results? Was there QC of the onsite methods and data? Is there a clear and informative report? PPDM HOUSTON 2012 38
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39 Units of Measure EPSG Geodetic Registry PPDM HOUSTON 2012 40
More Confusion in Geodesy Reference Units of Measure (many types of feet and 2 types of meters) Biggest Problem = U.S. Survey Ft vs. International Ft Some other Feet = Clarke s Foot, Sears 1922, 2 for Benoit (both 1895), Gold Coast Ft., 4 Indian Ft. (1865, 1937, 1962 & 1975) and 2 British Feet (1865 & 1935), 2 meters = International Meter and German Legal Meter Other linear units include Chains, Links, and Yards (with almost as many variations as the foot to meter relationships) PPDM HOUSTON 2012 41
If you remember nothing else.. Latitudes and Longitudes are not unique unless qualified with datum name! Projection Coordinates are not unique unless qualified with Projection name, Zone and Datum! Heights are not unique unless qualified with Surface Reference (Vertical Datum)! Orientations are not unique unless qualified with Heading Reference! Units are not unique unless qualified with Unit Reference! PPDM HOUSTON 2012 42
Data Tools Zone of the Geodetic Quagmire Knowledge Techniques PPDM HOUSTON 2012 43
Experts in Geomatics, Surveying, Positioning, Geospatial Data, and Mapping Sciences Geodetic Integrity: The Essential Basics for Data Managers and Users Michael Barnes www.apsg.info PPDM HOUSTON 2012 44