A well target is point or volume within the earth representing a geologic target through which it is intended that a well should pass.Drilling targets have location (CENTROID), geometry (SHAPE, THICKNESS, MAJOR-DIMENSION and MINOR-DIMENSION) and orientation (UP-VECTOR-INCLINATION, UP-VECTOR-AZIMUTH and ROTATION). Irregularly shaped targets may also be defined by using a polygon (SHAPE-POLYGON) to describe the target location and a portion of the geometry (SHAPE, CENTROID, and THICKNESS are expected). The following figures explain the shape and orientation aspects of well targets.
By convention UP-VECTOR-INCLINATION is constrained to lie between 0 (UP-VECTOR vertical) and 90 degrees (UP-VECTOR horizontal); UP-VECTOR-AZIMUTH is constrained to lie between zero and 360 degrees; if UP-VECTOR-INCLINATION is zero then UP-VECTOR-AZIMUTH should be zero also.
Label |
Restrictions |
Comments |
Optionality |
Units |
|
|---|---|---|---|---|---|
| NAME | C=1, | R=ASCII | 1 | ||
| POSITION | C=1, | R=OBJREF | 2 | ||
| SHAPE | C=1, | R=USHORT | 3 | MAND | |
| MAJOR-DIMENSION | C=1, | R=FDOUBL | 4 | COND | U |
| MINOR-DIMENSION | C=1, | R=FDOUBL | 5 | COND | U |
| ROTATION | C=1, | R=FDOUBL | 6 | U | |
| THICKNESS | C=1, | R=FDOUBL | 7 | COND | U |
| CENTROID | C=1, | R=OBJREF | 8 | ||
| SHAPE-POLYGON | C=1, | R=OBJREF | 9 | COND | |
| UP-VECTOR-INCLINATION | C=1, | R=FDOUBL | 10 | U | |
| UP-VECTOR-AZIMUTH | C=1, | R=FDOUBL | 11 | U | |
| UP-VECTOR-AZIMUTH-REFERENCE | C=1, | R=OBJREF | 12 | COND | |
| DRILLED | C=1, | R=STATUS | 13 | ||
| UPPER-SURFACE-SET-NAME | C=1, | R=ASCII | 14 | ||
| LOWER-SURFACE-SET-NAME | C=1, | R=ASCII | 15 | ||
| LOWER-DEPTH | C=1, | R=FSINGL | 16 | U | |
| GEOLOGIC-FEATURE-NAME | C=1, | R=ASCII | 17 | ||
| GEOLOGIC-FEATURE-SOURCE | C=1, | R=ASCII | 17 | ||
NAME C=1, R=ASCII
The name of the TARGET.
POSITION C=1, R=OBJREF
Reference to a 217-MAP-LOCATION giving the exact position within the target through which it is most desirable to drill.
SHAPE C=1, R=USHORT MAND
The cross-sectional shape of the target chosen from code values in the following table:
| Target Shape | ||
|---|---|---|
| Code | Mnemonic | Definition |
| 1 | POINT | The target is a point in the Earth |
| 2 | ELLIPTICAL | The target is elliptical |
| 3 | RECTANGULAR | The target is rectangular |
| 4 | SEMI-CIRCULAR | Depreciated |
| 5 | CIRCULAR | The target is cylindrical |
| 6 | POLYGON | The target is polygonal |
MAJOR-DIMENSION C=1, R=FDOUBL COND U
The major (longer) dimension of the target shape, not needed for shapes POINT or POLYGON. Required for shapes ELLIPTICAL, RECTANGULAR, and CIRCULAR.
MINOR-DIMENSION C=1, R=FDOUBL COND U
The minor (shorter) dimension of the target, not needed for shapes POINT, CIRCULAR, or POLYGON. Required for shapes ELLIPTICAL and RECTANGULAR.
ROTATION C=1, R=FDOUBL U
The azimuth measured from the north reference established by UP-VECTOR-AZIMUTH-REFERENCE to the vertical plane in which the target UP-VECTOR lies. Not meaningful for shapes POINT and CIRCULAR. Not required for shape POLYGON.
THICKNESS C=1, R=FDOUBL COND U
The thickness of the target as measured normal to the shape-defining face. Not needed for shape POINT. Required for all other shapes.
CENTROID C=1, R=OBJREF
Reference to 217-MAP-LOCATION which defines the position of the center of the target volume about which geometric construction of the target volume is performed. Not required for shape POLYGON.
SHAPE-POLYGON C=1, R=OBJREF COND
Reference to 217-MAP-LOCATION-SET which defines the polygonal outline of the target volume in the target-orienting plane. Required for shape POLYGON; not used for any other shape.
UP-VECTOR-INCLINATION C=1, R=FDOUBL U
The angular amount by which the UP-VECTOR is inclined relative to the vertical. See the object description for a fuller explanation of orientation. Not required for shapes POINT or POLYGON.
UP-VECTOR-AZIMUTH C=1, R=FDOUBL U
The azimuth angle, measured clockwise from the north reference established by UP-VECTOR-AZIMUTH-REFERENCE, to the vertical plane containing the target UP-VECTOR, and in which UP-VECTOR-INCLINATION is measured. See the object description for a fuller explanation of orientation. Not required for shapes POINT or POLYGON.
UP-VECTOR-AZIMUTH-REFERENCE C=1, R=OBJREF COND
Reference to an object of type 217-AZIMUTH-CORRECTION establishing the north reference axis used for UP-VECTOR-AZIMUTH and ROTATION. Azimuth values may be relative to true north, magnetic north, or grid north. A value for this attribute must be supplied anytime an UP-VECTOR-AZIMUTH or ROTATION value is encoded.
DRILLED C=1, R=STATUS
TRUE if the target has been drilled.
UPPER-SURFACE-SET-NAME C=1, R=ASCII
Name of a surface set at the upper boundary of the target.
LOWER-SURFACE-SET-NAME C=1, R=ASCII
Name of a surface set at the lower boundary of the target.
LOWER-DEPTH C=1, R=FSINGL U
Deepest, or cutoff depth. This may arise when a target is bounded below by an oil-water or gas-water interface.
GEOLOGIC-FEATURE-NAME C=1, R=ASCII GEOLOGIC-FEATURE-SOURCE C=1, R=ASCII
The name and source of a geologic feature containing or associated with the target. The feature may or may not be represented in the dataset as a 217-GEOLOGIC-FEATURE object.
Send questions and comments to
Jim.Theriot@POSC.org
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