Unique Well Identifier (UWI)
A. UWI format
example: 100.16-09-010-09W1.00
1 = Survey System Code
0 = Location
0 = Exception Code
16-09-010-09W1 = Legal Survey System
00 = Event Sequence Code
B. Survey Exception Code
The one-character code is used to indicate the survey system by which the well is located. In Manitoba (except in unorganized territory) the Dominion Land Survey (DLS) system of Townships and Ranges is used. The DLS system is always represented by a designated code of "1".
C. Location Exception Code
Represents the position and sequence of drilling of wells in a normal drilling spacing unit (16 ha). The character in position #2 can be alpha or numeric and represents the position of a well within the drilling spacing.
| Code | Well Spacing Unit and/or Position |
| 0 | - Forty Acre Spacing or more - usually center of LSD |
| A | - Twenty Acre Spacing or less - S.E. quarter of LSD |
| B | - Twenty Acre Spacing or less - S.W. quarter of LSD |
| C | - Twenty Acre Spacing or less - N.W. quarter of LSD |
| D | - Twenty Acre Spacing or less - N.E. quarter of LSD |
| S | - Road Allowances wells located South of LSD |
| W | - Road Allowances wells located West of LSD |
The number in position #3 indicated the chronological sequence in which the well was drilled when more than one well has been drilled in the spacing unit.
| Code | Drilling Sequence |
| 0 | - 1st well in the location |
| 2 | - 2nd well in the location |
| 3 | - 3rd well in the location (to the maximum of 9) |
NOTE: The number 1 is not used and the second well in a spacing unit is coded 2.
Some examples of Location Exception Codes for position and sequence are listed below.
| 1st well on normal spacing | - 00 |
| 2nd well on normal spacing | - 02 |
| 1st well in SE 1/4 LSD | - A0 |
| 2nd well in SE 1/4 LSD | - A2 |
| 1st well in SW 1/4 LSD | - B0 |
| 1st well in NW 1/4 LSD | - C0 |
| 2nd well on road allowance south of LSD | - S2 |
D. Legal Survey System
With the DLS system 11 characters are used to describe the well location.
SEC TWP RGE MER W 1
NOTE: For each item of any well location (LSD, SEC, TWP, etc.) the allocated number of positions must be filled by adding leading zeros where necessary.
E. Event Sequence Code
The character in position #15 is not required when the DLS system is used and therefore is coded 0 in order to maintain a complete UWI of 16 characters. The character in position #16 is used to identify drilling/completion operations at a well that yield unique geological/production data. The initial drilling and first completion are coded 0 and subsequent events 2 to 9. When a well is licenced it will receive an event sequence code of 0.
Some examples of significant events that would be assigned a differant Event Sequence Code are recompletion in a new zone, well deepening, conversion to a sald water disposal or water injection well, re-entry of an abandoned well and a dual completion.
