12.2.3.1 Wellbore Trajectory Representation

The wellbore trajectory representation has these main uses:

• Defines the geometry of the trajectory inside a RESQML coordinate system, so that geometrical interactions between its wellbore and other elements of a model are unambiguous. A wellbore trajectory representation can be associated with a WITSML trajectory, but it also must be able to stand by itself, so that it can represent wellbores during planning. The wellbore trajectory representation object includes sufficient information to uniquely define the location of a vertical well. However, all other wells should contain geometry described as a parametric line. (For more information, see 7.3 Parametric Points and Lines .)
• Serves as the reference for all the measured depth information captured along the wellbore. It references one MD datum (explained below), which provides information about the location of the measured depth datum and its type.
• Indicates the unit of measure and the range of measured depths covered by the trajectory. In the simple case, the range goes from zero to total depth. But for multi-lateral wells, the range may begin at kickoff points. A driller or logger domain is also included to indicate which measured depth reference was used.
• If a trajectory is based on a deviation survey, it can indicate the survey it originated from.

For multi-lateral wells, wellbores can have additional parentage information to indicate:

• Which wellbore trajectory it is kicked off from.
• The kickoff measured depth, both in the current wellbore trajectory and its parent wellbore trajectory. Each value is expressed in the measured depth unit of measure of its trajectory.
• If a trajectory is based on a deviation survey, it can indicate the survey it originated from.