Overview:
• The use of separation factor may lead to different level of collision
avoidance decisions depending on the input parameters being used
• Collision avoidance decisions can be taken without considering the size,
direction and the position of the error ellipses of the points of interest in
the offset and the reference well
• What needs to be considered is the position coordinates of the two points
of interest, their covariance matrices and the statistical significance of the
distance between them
• Could the significance level be adjusted to match a desired probability of
well collision?
Introduction to the Problem
What is the risk of collision between two petroleum wells?
All wellbore directional measurements are associated with uncertainty
Assumptions:
• Errors in the directional measurements propagate into the NEV coordinates of the
two closest points in the reference well and the offset well
• Errors in the NEV coordinates propagate into the shortest distance d between the
two closest points
....
View the entire Presentation:
Statistical Methods for Calculating the Risk of Collision
Bjørn Erik Loeng and Erik Nyrnes - Statoil ASA