Directional survey error models are used to generate well uncertainties known as ellipses of uncertainty. These shapes are translated into minimum safe distances from other wells to avoid collisions. A lot of focus is paid to the quality of the directional data and the derived results. While this issue has been dealt with for a long time in offshore directional drilling, current onshore horizontal pad drilling through old fields with expired vertical wells has recently increased interest in collision avoidance calculations.
This webinar will outline the principles of the standard survey error model and collision avoidance calculations used in the industry. It will also describe some of the pitfalls and counterintuitive behavior of the error model in terms of ellipses trends and collision separation factors.