let's focus on one block of 36 wells so 150-90-1 through 150-90-36
each block is represented by 3 different spacing units
150-90-1 - 150-90-12
150-90-13 - 150-90-24
150-90-25 - 150-90-36
Within the spacing unit 150-90-1 - 150-90-12 there may be 6 wells
I am assuming that there can only be 1 well per block within the spacing unit, in other words unit 150-90-1 could not have 2 wells in it, or could it?
I think regardless of this if you are recording the well number and the grid from which it came it should be fairly easy to choose a township and range then select a spacing unit and show the data relevant to that spacing unit.
For instance you could have a table
Code:
tblSpacingUnitGroups
SUG_ID SUG_Seq SUG_Lower SUG_Upper
1 1 1 12
2 2 13 24
3 3 25 36
Then when you run your query against a group of wells after having chosen township and range you would select a spacing unit group from a list which would translate the last digit(s) of the 'code' to determine which wells belong in your query.
You could also go more brute force like this
Code:
tblSpacingUnitGroups
SUG_ID SUG_Group SUG_Number
1 1 1
2 1 7
3 1 12
...
10 2 13
11 2 16
15 2 24
...
20 3 25
21 3 36
then you could just strip off the last character and make sure it matched the group you were looking for.