FAST, EASY, INEXPENSIVE PROGRAM FOR MAPMAKING FROM SPREADSHEET

These days there is a strong push for geologists to invest in sophisticated turnkey mapping systems that cost tens of thousands of dollars and require beastial hardware.

The author has seen many geologists lured into this trap (himself for one), buying digital land grid at $10/township, well data on floppy disks at $1/well, 80486 computers with massive hard disks, megabytes of RAM, super-VGA monitors, and module after $3,000 module of mapping software.

When the dust clears you are looking at a $30,000 hole in your wallet with nary a map to show for it,

Then comes the "break-in" period. It turns out the computer has a 10 mHz bus speed, which won't work with your 8 mHz cards. Your video board performs like a sloth (indicating you should have sprung for the 1 megabyte model), so that your secretary's vintage EGA runs rings around your 20 in. NEC Multisync.

Even worse, the super-enhanced resolution mode you wanted to use flickers so badly you might as well sit in front of a strobe light.

You determine that none of your software knows how to access that extra 4 megabytes of RAM you bought.

You learn that your mapping package includes a driver for your plotter that almost but not quite lines up adjacent section lines, that your digital land grid has several sections that are 1 1/2 miles high, and that your well data coverage has holes in it big enough to drive a prospect through.

You discover there is no way to search your database for wells that produced from a specific pay zone, that it is simpler to take your old spreadsheets of well data and re-key them than wrestle with the "Import" option in your new software, and that the DXF files your software creates cause your CAD package to self-destruct with an interesting sequence of "unknown command" and "missing shape file" errors.

The final blow comes when you deduce the hardware copy-protection key on your parallel port draws just enough power to keep your printer from working.

So as your landgrid takes 10 min to display (with all lines the same width to make finding townships a challenge), and as your well data take another 10 min, you decide the best thing about computerizing your work is the guaranteed coffee break each time you regenerate your screen.

What you have is an adequate system for regional mapping. In the mature areas most geologists work, this translates into a dandy system for reinventing the wheel.

The author would like to suggest a better plan of attack for geologists contemplating the high-tech plunge. This approach doesn't convert half one's salary into a workstation and the other half into software.

SIMPLE PLOT PROGRAM

Most geologists use spreadsheets to hold well data.

Spreadsheets calculate subsea depths, allow the geologist to make diagrammatic cross sections to check correlations, and are generally handy with well information.

Wouldn't it be great to be able to take a spreadsheet of well data and instantly turn it into a base map? The program for QKPLOT, or "QuickPlot," that this article describes does exactly that.

QKPLOT is a program written in True Basic that takes a comma delimited text file of well data and converts it into an AutoCAD script file, The script file can be brought into AutoCad with the 'SCRIPT' command and creates a familiar township and range map from the geologist's data.

Townships and sections are numbered, standard well symbols are used, and each well is annotated with a label or datum beneath.

OKPLOT generates perfect, nondistorted landgrid. Wells are located on top of the landgrid to the nearest foot, using negative footages for West ranges and South townships. The spotting engine that places the wells operates by deciphering legal descriptions (Fig. 1).

It is extremely fast and robust enough to handle "33.33 N 270 NE 1334 FSL 667.4 FWL SW." It goes without saying that one must be working in a state that has a township and range grid (apologies to those mapping Texas).

Each row of a typical OKPLOT input file holds a different well, while each comma-separated value in the row is a different kind of information for that well (see table).

If you had originally typed this information into a spreadsheet like Excel, you could easily generate a suitable file for QKPLOT by saving it using Excel's "CSV" option (for comma-separated values).

Other spreadsheets may be less accommodating, forcing you to insert columns of commas manually, then sending the data to a nonformatted print file (Lotus or Quattro users could automate this process with macros).

If you are using an actual database like FoxPro, then it is easy to design a report that puts the pertinent well data into the proper form and prints it to a file. For quick jobs you could enter well data directly into your word processor, saving it as a pure ASCII, or text file.

Each line of a QKPLOT input file contains:

Section,Township,Range,Spot location,symbol,well label

Each item has the following format:

Section = a number from 1 to 36

Township = a positive number and either N or S

Range = a positive number and either E or W

Spot location = a legal description, like NE NW SW or N2 S2 SW NW or 334 FSL 1458.4 FWL SW or 220 W 130 NW SE, etc.

Symbol = a well symbol, like GAS, G&O, OIL, SWD, D&A, etc.

Well label = a number or line of text to appear below each well

Syntax of the spot location is important. The rules that should be followed are:

1. Spot locations have the largest-scale descriptors on the right, the smallest-scale on the left.

2. Each descriptor should be separated from the next by a space, as in "NE SW NE."

3. Avoid the "/" slash. Use "S2" instead of "S/2" (south half). Also, there is no need for "/4," as in "NE/4." Use just "NE" instead.

4. For locations that specify an offset from a section or quarter section line, use "FNL" (from north line). Similarly, you can use FEL, FWL, FSL. A well 330 ft from the south line and 428.5 ft from the west line of the northeast quarter would be entered as "330 FSL 428.5 FWL NE" (omit any ' signs). You can even specify offsets from a quarter-quarter section.

5. Wells sometimes use nautical "bearing" syntax. To spot a well 225 ft northeast, 75 ft north, and 30 ft west of the northeast of the northeast, you would enter 225 NE 75 N 30 W NE NE."

6. Concatenate descriptors all you wish, but keep the small-scale to large-scale progression in mind. "NE 300 N" would be meaningless, but "300 N NW" would be 300 ft north of the center of the northwest quarter.

7. Also keep the logic of the entire description in mind. The assumed starting point is at the center of the section, so "N2 NE" makes sense as the north half of the northeast quarter. "NE N2" doesn't make sense, because the north half of a section doesn't define a square quadrant.

Well symbols can be one of GAS, G&O (gas and oil), O&G (oil and gas), OIL, SWD (salt water disposal or injector), J&A (junked and abandoned), TA (temporarily abandoned), and D&A (dry and abandoned). Put an "A" or "AB" in front of a symbol name to indicate an abandoned producer, like AOIL or ABGAS.

MAKING THE MAP

When you run QKPLOT, an input form appears that asks for the names of your input file and the name to give the output script file (be sure to give it a file name with an SCR extension).

It is also necessary to specify the township and range of the bottom-left and top-right corners of the map you wish to make.

QKPLOT generates contiguous townships sufficient to cover the area, spots all the wells from your file that lie within this area, and creates a small script file on disk.

To load your base map into AutoCad, start a new drawing and type "script" at the AutoCad prompt. When asked for the name of the script file, enter the same file name created with QKPLOT (minus the SCR extension).

As the script file loads, the commands creating the base map will scroll across the bottom of the screen. When all of the landgrid is built, the display will zoom out to show the full extents.

After that the geologist can watch each well being spotted and annotated. A final redisplay signals that the script file has finished loading.

Bringing one's maps into AutoCAD is a good idea. This allows the author to customize them, slide townships east or west to handle known distortions in the landgrid, add hand contours, title blocks, and so on.

And by using a coordinate system based on footage from the state township and range origin point, one gains the ability to seamlessly merge drawings. If it is necessary to map a couple of townships adjacent to a previous area now saved as an AutoCAD drawing, the new map can be imported into the old one and the two will line up perfectly.

CONTOURING

One of the best bargains around is the $15 QuickSurf "Convertible Demo."

This is a contouring package that can work within or without AutoCAD.

The author of this article designed QKPLOT with the QuickSurf contouring package in mind, so when QKPLOT generates a script file it also makes a separate layer in the user's drawing called POINTS. All the X,Y,Z points necessary for contouring reside on this layer.

A limitation on the demo is that it won't let you specify a distinct contour interval, choosing instead contour intervals at random. This isn't a major problem since the user can specify a total number of contour levels to use (you can easily get enough detail on a map to portray your data accurately).

QuickSurf uses a combination of triangulation and gridding techniques that has an uncanny ability to mimic hand-contouring, and it is the single fastest contouring system this author has ever used.

To contour a base map in AutoCad, first turn off all the layers except the one called POINTS. Then, assuming you have the QuickSurf menu properly loaded, pull it down to the "extract points" option. This pulls all the X,Y,Z triplets out of the POINTS layer and dumps them to a file on disk, ready to be contoured.

You can set up other contouring parameters by using the QuickSurf menu, then select 'run QS'. The demo will shell out of AutoCad, take just a few seconds to contour the file of X,Y,Z values, then return to AutoCad and load the new contours.

After you turn all the base map layers back on, notice that the contours precisely overlay the control wells. Fig. 2 shows a map created using OKPLOT and QuickSurf loaded into AutoCAD.

The author believes you will find the combination of QKPLOT with a spreadsheet (or database) and AutoCAD far more useful than a dedicated mapping system. Maps can be made faster, will look better, and the user can apply the skill gained with AutoCAD to many other tasks.

If your work involves small prospects scattered across a large province such as the Midcontinent, QKPLOT will free you from the tyranny of digitized landgrid, strange data formats, and tedious input routines. It can make one's job much easier.

QKPLOT and QuickSurf "Convertible Demo" can be downloaded from the AutoCAD forum on CompuServe. Anyone who does not have access to CompuServe can order the QuickSurf demo for $15 from Schreiber instruments (800/252-1024).

True Basic and its support libraries are available from True Basic Inc., 12 Commerce Ave., West Lebanon, NH 03784 (603/298-8517).

AutoCad is a product of Autodesk Inc. and is available through authorized computer dealers.

The author of this article will also make a compiled version of QKPLOT available for $15 through PetroLogic, 3943 S. Delaware PI., Tulsa, OK 74105.

Copyright 1991 Oil & Gas Journal. All Rights Reserved.