Claritas 3D - Land Geometry Example Workflow for an Example 3D Land Geometry Dataset supplied by USGS.

Introduction The aim of this presentation is to illustrate the work flow used to derive a 3D Land Geometry for a dataset supplied by the USGS. The presentation will explain how the Meta data was edited/reformatted for input to the Claritas Geometry tool. Will detail the process by which the Geometry is created using the Claritas tools.

Supplied files – Observers Logs

Additional Text Information

Survey Information in SPS Format

Comments The Raw Meta data received from the USGS needs to be reformatted before it is suitable for input to the Claritas Geoemetry tools. The Survey information (SHOT_PEG, Easting, Northing and Elevation data or REC_PEG, Easting Northing Elevation files) were concatenated into a single file. This file was then reformatted using the ASCSUR utility. The Observers logs were edited to generate an input file suitable for the ASCOBL utility. Firstly the individual files were concatenated to produce one single Observers file with all Shots included. XEDT editor was used to remove all non-printing characters and to add an OBSERVERS3D format SDE header block to the file. The resulting file has certain key fields which are only populated for the first line of each Shotpoint. The output file from the previous stage is then opened with XSDE, and for each numeric column the increment is set to 0, non-numeric to c. As you scroll down through the file any blank columns are filled with a copy of the last value in that column. The resulting file can then be input to the ASCOBL utility to prep the file for input to Geometry.

Observer Information after 2nd stage of formatting

Ascobl parameters

Observers Information after ASCOBL

Ascsur parameters

Survey Information after ASCSUR

Geometry Tool Now that the survey and observers logs have been reformatted and are suitable for input into the Claritas Geometry tool we can commence building a Geometry database for the survey. The newly created *.sur file is used as the Main input to the initial Geometry parameter form. The two Mandatory parameters are highlighted in red and are : Input Type :- Default is Claritas (i.e. *sur file) alternate option is P1/90 (not implimented). Geometry Name : example.sur Generally all other parameters can be defaulted. If you opted to not remove an Origin from the survey data as part of the ASCSUR process you may be piped through the subsur utility before Geometry tool in order that any large co-ord values do not lose precision.

Initial Geometry parameter form

Geometry Tool – Main Application window

Geometry Tool All the following operations are know accessed via the different buttons along the bottom axis of the tool. Zoom button allows the user to change the plot scale of the Map window by set ratios, or to create a new zoom window of a requested area. The Make button allows access to : 1) Create Geometry Database (Hotkey g) 2) Read CDP Gather from *.geom (Hotkey r) 3) Linear (2D) CDP Gather (Hotkey l) 4) Wiggly (2D) CDP Gather (Hotkey w) 5) 3D CDP Gather (Hotkey 3) 6) Floating Datum Statics (Hotkey f) The Draw button allows the MAP display to show different QC displays such as Midpoint scatter, Shot_Pegs, Rec_Pegs, CDP Fold, Lost traces, etc. Label allows manipulation of Horizontal and Vertical Axis labels. Hitpoints Button allows, picking of geometry knee points (Manual and Automatic) Specification of 3D Grids. Info button allows the Geometry information for Shot_Pegs, Reciever_Pegs , CDP’s and other geometry information to be interrogated by the user.

Geometry Database creation – Parameter form The seismic Geometry Definition form, initialises the *geom database file and references the *.obl and *.sur files. Length Units can be specified as Metres or Feet. N.B:- Height and Co-ordinate scalars although specified as Decimetres/Metres will be appropriate to the selected Length Units.

Geometry Database creation – Summary form This summary provides information on which Shot-pegs or Receiver_Pegs have not been found.

Geometry Tool – 3D Grid Definition There are three options available within the Geometry tool to define your 3D processing grid:- Enter two peg locations in the inline direction. Specify an Origin Co-ordinate and il and xl angle in degrees. Or three co-ordinates, Origin, co-ordinate in the il direction, and co-ordinate in xl direction. The following summary form shows the key information for your grid definition.

Geometry Tool – 3D Grid Definition

Geometry Tool – 3D CDP Binning Parameters Binning information is output to the *geom database file. CDP’s are defined as a concatenation of the inline and crossline numbers. Mandatory Parameters are highlighted in Red. N.B:- As the geometry was initially created with measurement units set as Decifeet, all IL & XL spacing and bin widths are specified in Decifeet, i.e. 110 feet is 1100 Decifeet.

Geometry Tool – 3D CDP Binning Summary This summary information is retained in the *.clg file, and all binning information is updated and the initialised *geom file is written to the selected directory. Example : /Project/Line/Support/Geometry. Now the *geom file has been updated and written out a number of Diagnostic displays can be reviewed including fold maps, bin position maps etc.

Geometry Tool – Fold Map

Geometry Tool – Floating Datum Statics The Final process within the Geometry tool is the generation of Floating Datum Statics. Parameter form is pretty simple and self explanatory.