Neuralog Well Geodetics


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Well Geodetics and the importance of Geodesy in Master Data Management

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Neuralog Well Geodetics

  1. 1. NeuralogWell Geodetics in Master Data ManagementRobert E. BestDean C. Mikkelsen<br />Turning Paper Into Petroleum<br />
  2. 2. Outline<br />What is Well Geodetics?<br />Why is it Important in MDM?<br />Geodesy Concepts<br />Standards<br />Implementation in MDM<br />Summary<br />
  3. 3. What is Well Geodetics?<br />The science of locating a well’s surface and bottom locations.<br />Location with respect to other features:<br />Other wells<br />Geopolitical boundaries<br />Hydrocarbon targets<br />Geological features<br />
  4. 4. Why is it Important?<br />When combining well data of different ‘vintages’, different systems may have been used.<br />In order to accurately map your wells, geologic features and boundaries together, the same Coordinate Reference System (CRS) must be used.<br />
  5. 5. Dramatic example of what might happen<br />Lake Peigneur, Louisiana, USA 1980.<br />Well drilled a little too close to salt dome.<br />
  6. 6. Result<br />Lake drained in 2 days.<br />Rig and several barges lost (no life lost)<br />Freshwater lake became a saltwater lake<br />
  7. 7. Bottom Line : Check the CRS<br />Failing to account for these differences can create errors of 100’s of meters.<br />A wells report from the 1951 may have a completely different CRS than one from 2001.<br />The main factors are the CRS used<br />Datum - Ellipsoid<br />Projection - North Reference<br />
  8. 8. Reference Systems and Coordinates<br />Depth Reference<br />Measured Depth<br />True Vertical Depth<br />Inclination Reference<br />Vertical Reference<br />Direction Measurement<br />Azimuth Reference<br />Quadrant Bearings<br />
  9. 9. Depth Reference Points – Land and Offshore Rigs<br />Elevation: Kelly Bushing, Ground Level, Elevation above Mean Sea Level (MSL), MSL<br />Land Rig<br />Offshore Rig<br />Elevation: Platform, Seabed, MSL, Kelly Bushing<br />Vertical Component of well location is vital to integrity of the data set. Correctly referenced height data (ellipsoid, elevation or z). May prove challenging for legacy data.<br />
  10. 10. Map Projections<br />Map projections display the earth on a ‘developable’ surface<br />Plane<br />Cone<br />Cylinder<br />Distortion will be a result<br />Shape<br />Azimuth<br />Linear<br />
  11. 11. Universal Transverse Mercator<br />Widely used internationally<br />Zone/Grid system<br />60 Zones, 6deg width<br />
  12. 12. UTM Grid<br />Positive Easting and Northing coordinates<br />Grid Convergence (difference between true/grid north) zero at equator and central meridian<br />
  13. 13. North Reference<br />Azimuth measurements, such as in a well deviation survey, require a North Reference.<br />‘North’ can be referenced to one of the following:<br />True North<br />Direction of the Earth’s Northern Geographic Pole<br />Grid North<br />Map North (North Direction of the Y-Axis of a Cartesian Grid)<br />Magnetic North<br />Direction of the Earth’s Northern Magnetic Pole<br />
  14. 14. True North<br />Parallel to lines of Longitude<br />
  15. 15. Grid North Reference<br />North direction parallel to Y Axis of map<br />
  16. 16. Grid North Reference - UTM<br />True North<br />Grid North<br />Angle between the two is the Grid Convergence Angle<br />
  17. 17. Application in Well Deviation Surveys<br />3 basic measurements<br />Azimuth (with respect to a North Reference)<br />Deviation Angle (from vertical)<br />Measured Depth<br />Standards vary for North Reference but some basic rules of thumb:<br />International/Onshore USA – True North<br />Offshore USA – Grid North<br />
  18. 18. Application in Well Deviation Surveys<br />Q: What happens if the wrong North Reference is used?<br />A: The well bottom hole location will be in the wrong place!<br />In UTM, the issue is more acute the farther you get from the equator and central meridian.<br />
  19. 19. Datums and Ellipsoids<br />The earth is usually modeled as a ellipsoid.<br />Regional maps frequently employ a datum to better match the area by employing an ellipsoid shift<br />
  20. 20. Common Ellipsoid & Datums<br />European <br />Datum <br />International<br />North American Datum<br />Clarke 1866<br />WGS Datum<br />Tokyo Datum<br />Bessel<br />South American Datum<br />International<br />Arc Datum<br />Clarke 1880<br />
  21. 21. Horizontal Datums<br />Many nations established their own datum<br />Standards and procedures vary widely<br />Coordinates from different datums are completely incompatible<br />Relative to Initial Point of Datum<br />Will vary as a function of Ellipsoid parameters<br />
  22. 22. Datum Transformation – 7 Parameter – One Method<br /><ul><li>To translate one datum to another we must know the relationship between the chosen ellipsoids in terms of position and orientation. The relationship is defined by 7 constants.
  23. 23. 3 - Distance of the ellipsoid center from the center of the earth (X, Y, Z)
  24. 24. 3 - Rotations around the X, Y, and Z of the Cartesian Coordinate System Axes (, , )
  25. 25. Scale change (S) of the survey control network</li></li></ul><li>Transformation between 2 Horizontal Datums<br />The two ellipsoid centers called  X,  Y,  Z <br />The rotation about the X,Y, and Z axes in seconds of arc<br />The difference in size between the two ellipsoids<br />Scale Change of the Survey Control Network S<br />
  26. 26. What does this mean?<br />Longitude and Latitude are not unique for a given location.<br />Must know the associated datum<br />f1<br />f2<br />f1 ¹f2<br />
  27. 27. Units of Measurement<br />Several different units of measurement have been used in location of wells and seismic.<br />Unambiguous identity and correct knowledge and application of units of measurement are required.<br />Eg. “Foot” might be any of the following:<br />International Foot<br />US Survey Foot<br />British Foot (Sears 1922)<br />British Foot (Benoit 1895 A & B, 1865, 1936)<br />Indian Foot (1937, 1962, 1975)<br />Gold Coast Foot<br />
  28. 28. What magnitude of errors could happen?<br /><ul><li>Wrong geodetic datum:
  29. 29. Several hundreds of meters : 100’s m
  30. 30. Incorrect ellipsoid:
  31. 31. Horizontally: 10’s m
  32. 32. Height: 0-100’s m
  33. 33. Wrong map projection:
  34. 34. Entirely the wrong projection: 100-1000’s m
  35. 35. Partly wrong (i.e. one or more parameters are wrong): 100-1000’s m
  36. 36. No geodetic metadata  meaningless coordinates
  37. 37. Datum
  38. 38. Ellipsoid
  39. 39. Prime meridian
  40. 40. Map Projection</li></li></ul><li>Standards – OGP/EPSG/UKOOA<br />The OGP Geomatics Committee is now the custodian of upstream geodesy information for international E&P<br />Was born from the European Petroleum Survey Group (EPSG) and UKOOA Standards.<br /><br />
  41. 41. EPSG Database<br />Comprehensive database of ellipsoids, datums, projections and coordinate reference systems used worldwide<br />
  42. 42. Standards - APSG<br />Formed in 1998 to promote exchange of ideas and issues encountered in worldwide E&P. Individuals come from within the oil and gas industry, from majors to service companies.<br />Definitions of multiple Horizontal Datums<br /><br />
  43. 43. Implementing Geodetics in MDM<br />Given the previous discussion, a Master Data Management Solution should be able to:<br />Support grid and Lat/Lon coordinates<br />Support individual CRS for an entity (well, seismic navigation, etc)<br />Support the storage of the geodetic metadata to specify the CRS<br />
  44. 44. Example MDM Model - PPDM<br />Professional Petroleum Data Management Association<br />International Data Modeling consortium<br />Members companies include Oil & Gas and Technology Firms<br />Model refined over 20 years<br /><br />
  46. 46. Transformations in PPDM<br />CS_COORD_TRANSFORM <br />CS_COORD_TRANS_PARM<br />CS_COORD_TRANS_VALUE <br />
  47. 47. Well CRS in PPDM<br />WELL<br />WELL_NODE<br />CS_COORDINATE_SYSTEM<br />
  48. 48. Well Deviation Survey in PPDM<br />WELL<br />CS_COORDINATE_SYSTEM<br />WELL_DIR_SRVY<br />WELL_DIR_SRVY_STATION<br />
  49. 49. PPDM Implementation<br />Each entity (well, seismic, etc) has individual CRS specification for pertinent locations.<br />Datum, Ellipsoid and Transformation parameters stored and tied to CRS.<br />Full parameters needed for transformation to any system stored.<br />
  50. 50. Conclusions and Recommendations<br />Gather and store all the geodetic meta-data available for your wells and seismic.<br />Be aware of how missing or incorrect information can effect your mapping.<br />Employ a MDM strategy to account for these factors at the outset.<br />
  51. 51. Thank You!We appreciate your spending time with us today.<br />Turning Paper Into Petroleum<br />