Shareware Grab Bag/Shareware Grab Bag.iso/008/cps.arc/CPSNOTES.DOC

Text File | 1985-12-19 | 5.9 KB | 116 lines

Jeffrey D. Prouty                                      18 December 1985
Jordan Oil & Gas Company
P.O. Box 1919
Santa Rosa, CA  95402


Dennis Dubose, et al
Radian Corporation
P.O. Box 9948
Austin, TX  78766


Re:  Use of AutoCAD for data input to CPS/PC


AutoCAD by AutoDesk may be used to prepare x, y, z, polyline, text, and
symbol data for input to CPS/PC.  This may be done as one is drawing a
basemap on which CPS-generated contours may later be plotted.  Seismic
time horizons may also be digitized with AutoCAD, plotted at shotpoints
on the basemap and then extracted as data for CPS.

Basemap preparation begins by starting AutoCAD with a prototype drawing
which sets up the initial drawing environment.  My prototype basemap is
called MAP.DWG and is loaded by default.  It calls my mapping menu,
ATT0.MNU, which contains four submenus which may be accessed from the
screen, cursor buttons, or tablet menu area.

I proceed to build the basemap, usually with land grid from USGS topos,
wells from PI lease maps, and seismic from shot point maps, placing data
on the appropriate layers.  Cursor buttons 8 thru D spot and scale the
well symbols.   Well tops may be input as the wells are spotted by calling
up the ATT1 OR ATT2 menus which prompt for one or two data per well.
These data are stored as attributes WDATA1 and WDATA2 which may be made
visible by setting ATTDISP to ON.  If ATT0 or ATT1 are used both or one
attribute will be given the default value of 99999 (my INDT value in CPS).
Of course, any number of data may be stored in this manner, including
well name, operator, KB, etc.  The well symbol type is inherent to the
block name and will be extracted as the CPS symbol code for each well.

Seismic lines are usually plotted on separate layers using the seismic
submenu.  Lines must be posted in ascending order if data is to be
automatically inserted (see below).  Button 7 (BOL) begins a line, setting
the initial shotpoint number to 100 and the label increment to 10.   These
may be changed via AutoCAD's LISP language, ie. "(setq sp 94)" or "(setq
inc 9)".  Remaining shotpoints are plotted using buttons 4, 5, 8, and 9.
Major shotpoints are labeled with sp which is incremented by inc. All
shotpoints have invisible attributes tagged SDATA.  Menus could allow
immediate data entry as with the wells, or digitized data may later be
added to each plotted shotpoint via a menu generated by a program (see
below).  The line may be ended with button B (EOL) and labeled with C.

Data stored as attributes by wells and shotpoints may be edited with the
ATTEDIT command and extracted with the ATTEXT command.  The manual has
details.  Choose the SDF extraction format.  Examples of my template files
are included as *.TXT files.

I should note that most of my most frequently used AutoCAD command
sequences are stored as macros under SuperKey and therefore do not appear
as menu selections.  Also, viewing and editing menus, scripts, data, and
template files while still in AutoCAD is easy with SideKick's Notepad (use
the MENU command to retrieve edited menus and try out changes).  The SHELL
command will let you out to DOS to do such things but may not let you back
into AutoCAD - save your drawing first!

Digitizing horizons from seismic sections is more complicated but can be
very efficient when working with many horizons on many lines in a given
area.  Begin by starting a new drawing, usually with the name of the
seismic line, using SEIS.DWG as the prototype, ie. "DB01=SEIS".  Call the
SeisSec submenu.  Snap aspect is set to 1 inch horizontal which must
correspond to your sampling interval (usually every fifth shotpoint).
Change if necessary, but leave the vertical snap resolution at .0001 inch.

Calibrate the tablet to your seismic section in inches.  Place 0,0 at
about 1.5 seconds on the leftmost sampled shotpoint.  Note this shotpoint
and time for later use.  Choose the second point at least 10 horz. and 10
vert. inches away, but somewhere in the upper right corner of your
section.  Use "inches" as scaled on the section, not true inches, to
adjust for printer and paper stretch.

Number the horizons and record them by moving the cursor along the
horizons and pressing the horizon number on the cursor keypad at each
sample interval.  The crosshairs should snap between horizontal sample
shotpoints but have full vertical freedom.  ATTEXT with the F key using
SEIS.TXT as the template and the drawing name as the extract file name
(the default).

Now, you may either END the drawing or use the SHELL command to return to
DOS and run the BASIC program SPOST.  This pgm. reads the extract file and
converts x and y coordinates to shotpoints and time.  You may also take
isochrons between any horizons, print tables of the results, and create a
.MNU file with the name of the seismic line.  Running the program should
be self explanatory.  You may then return to AutoCAD to digitize a new
section.

The menu files created by SPOST may be called in to automatically ATTEDIT
the seismic lines posted above on your basemap.  Freeze all but a set of
non-intersecting seismic lines.  Load one seismic line menu.  Select
horizon or isochron to post.  Window that line and the digitized values
will be edited into INDT attribute positions.  Repeat for all lines on the
screen then freeze these, thaw a new set of lines, and continue.  ATTEXT
using SDATA as a template file to create an x,y,z data file ready for CPS.

These are only a few, simple ways AutoCAD may be used for IO to and from
other programs.  I've enclosed an excellent article from CADalyst which
surveys the many roads into and out of AutoCAD.  I'm sure it will generate
many new ideas usefull to your CPS interface.  If I may be of any further
assistance feel free to call [phone].  Keep me posted!


                               Sincerely,



                               Jeff D. Prouty