Borehole Trajectory

In order to accurately track a borehole’s trajectory, either a survey can be run against it or Measurement While Drilling (MWD) techniques can be used during the drilling operation, but in both cases the results are stored as a survey. One survey can be designated as its legal survey (survey used for legal purposes), and one designated as its preferred survey (the survey to be used for calculation purposes). There is no reason why the legal survey and the preferred survey cannot be the same survey.