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This function can be used to compute Latitude-Longitude coordinates for a group of selected wells using footage calls or "spot calls" referenced to a Township-Range-Section or Texas Survey-Block-Section land grid file. Several land grid files can be selected and processed simultaneously.
Special processing has been added to handle Texas Locations using survey, block and section. In this case, the TMC Texas format file is used as land grid files. A problem that Petra addresses is the ability to equivalence mismatched survey names between IHS well data and TMC land grid files. For example, IHS might have the survey name as "UNIV LDS" while TMC has it as "UNIVERSITY LANDS". Petra provides for the use of an equivalence file to match these survey names. Petra can scan the TMC files and build a list of mismatched survey names which the user can then assign matches and save them to the equivalence file.
Data required for this function is:
1. Petra well database populated with footage calls, i.e., 1520 FNL, 660 FWL, or quarter "Spot Calls", i.e., NESW in the Location>Township or Location>Texas information.
2. A land grid file containing section boundaries in latitude-longitude. Petra supports the following formats of land grid data sets:
Tobin Infobase
Topographic Mapping Company (TMC)
Platte River (same as TMC)
Whitestar Data in TMC format
TMC Texas format
After selecting the appropriate options, click the "Compute" button the process the wells. After viewing or printing the report, exit the screen by clicking the "Done" button.
Data tab
Land Grid File(s)
Use the browse button to select one or more data files containing land grid information. All files selected must be of the same format. See valid formats above.
Scan For Survey Name Match... - If using TMC Texas locations format, you will have this optional button. First, you should specify the "Survey Equivalence File" (see below) before clicking this button. It will process all land grid files and find any well data survey names that do not match the land grid files. A new tab will appear labeled "Survey Name Match" for you to assign matches. (See Assigning Survey Name Matches)
DB Records Containing Footages
Select which database records have been populated with footage values. Areas outside Texas normally use the "Township Records" option while projects in Texas will normally use the "Texas Location Records" options.
Texas (TMC) Locations Survey Name Match
This section contains options for matching Texas survey names when using Texas TMC land grid files.
Percentage Compare - Well data survey names are first compared with the land grid survey names using a "percentage" matching technique. You may enter a value from 1-100%. Higher numbers mean the names must match more precisely.
Use Survey Equivalence File - This file contains survey names and alias or equivalent names that aid in matching survey names. Each survey equivalence is represented by 2 (or more) records. The first record begins with a "1" and identifies the survey name at it appears in the well data base. This is followed by one or more alias records which begin with a "2". The alias name is the name as it appears in the land grid file. The format of this file is as follows:
1SURVEYNAME
2SURVEYNAMEALIAS
2SURVEYNAMEALIAS
1SURVEYNAME
2SURVEYNAMEALIAS
...
Edit Equiv. File...
The survey equivalence file can be viewed or modified using a text editor if you wish. Care must be taken not to alter the format of the items listed in the file.
Options tab
Wells Which Get Locations Computed
This option can be used to restrict which wells will have their locations computed. The "All Selected Wells" will attempt to compute locations for all wells currently selected in the main module. The "Only Wells With Zero-Valued Lat-Lons" option will skip any selected well that does not have a latitude and longitude of zero.
Calculate Locations For
This option determines with location is computed. Choose either "Surface Locations" or "Bottom-Hole Locations" option.
Backup Original Locations
This option can be used to save old well lat-lon values to a file prior to computing new locations. Check the "Create Backup File" option and use the browse button to select or enter a file name. It is highly recommended that you make a backup of the original well locations during this process. The backup file is an ASCII file containing the UWI (or API#), Latitude and Longitude as a comma separated format.
Method tab
Location Source
Either footage call values or spot calls, such as, "NE SE NW" can be used.
The current version of this function will compute locations for full sections when the "footage reference" value is blank or contains the string "SEC". When the reference value contains one or more occurrences of the keyword "QTR", then the footages are interpreted as being from a quarter section line and not from the section line. In this case, the section polygon is converted to a "regular" 640-acre section then subdivided into the appropriate quarter. If the reference contains QTR QTR then the quarter subdivision is repeated a second time. Also, this quarter subdivision relies on having a valid spot call which ends in values such as NE, NW, SE or SW, etc.
Use Spot Call if footages can not be used...
Check this option to force the use of spot calls if the footages do not reference a full section.
Output Mode
This option is critical and determines what happens with newly computed locations. Use this option to preview or test the calculations prior to modifying the locations in the database. All options generate a process summary report (see report tab for details).
Generate Report Only (Do Not Modify Locations) - This option computes new locations but does NOT UPDATE the database with them.
Compute new Locations In the Database - This option computes new locations and UPDATES the locations in the database. It is wise to create a backup file of the original locations when using this option (see data tab for details)
Export New Locations to an ASCII File - This option will write the new locations to a data file but will NOT UPDATE locations in the database. Enter a file name or use the browse button to define the output file.
Report File
A report file called SPOTWELLS.TXT in the project's "reports" directory records a summary of the location calculation process. Each well is listed showing its processing status. Wells with new locations computed will show the new Lat-Lon values and the distance in feet or meters, depending on the map projection, from the original location (if non-zero). The location line is prefixed with a letter indicating how the location was computed. The prefixes are "F" for footage from section line, "Q" for footage from quarter section line, and "S" for spot call calculation.
The report is displayed in NOTEPAD and can be printed or saved to a new file. Note, this file is overwritten with each execution.
Survey Name tab
This tab is displayed after scanning for survey name matches using Texas TMC files. The left side shows the well data survey names that Petra could not match with any of the TMC land grid file survey names shown on the right.
Assigning Survey Name Matches
You can assign alias or equivalent survey names by choosing one or more items from the right side list that match with a single item from the left side list. Once you've made your assignments, add them to the survey equivalence file by clicking the "Add To Equiv. File" button.
Editing the Survey Equivalence File
You may view or edit the equivalence file at any time by clicking the "Edit Equiv. File" button. Just be careful not to alter the format of the items listed in the file.
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