Methods for predicting and adapting to high frequency torsional oscillation
AssigneeSchlumberger Technology Corporation
InventorAshley Bernard Johnson
Life of this patent
Estimating the term…
Abstract
An accurate and elegant model is provided to characterize HFTO. For Type 1 HFTO, the model can predict frequency of the HFTO based on the distance between a reference location on the bottomhole assembly (e g., the end of the drill bit) and a point 40% up the motor. In short BHA strings there is the fundamental frequency while in longer BHA the first harmonic is used. For Type 2 HFTO, the model can predict frequency of the HFTO based on distance between a reference location on the bottomhole assembly (e.g., the end of the drill bit) and the first slick contact point, which is optionally in the middle of a long flex joint.
Claims7
A method comprising:
- measuring frequency of high frequency torsional oscillation (HFTO) in a bottomhole assembly (BHA);
- using a model correlating frequency of the HFTO to distance relative to a reference location on the BHA to identify a position of a HFTO node in the BHA;
- when the HFTO node is at a contact point in a curve of a drilled wellbore, reducing dogleg severity or sending a recommendation to reduce dogleg severity;
- when the HFTO node is at a contact point in a lateral of the drilled wellbore, back reaming or sending a recommendation to back ream;
- when the HFTO node is in a motor of the BHA, changing drilling parameters or sending a recommendation to change drilling parameters;
- and
- after drilling, performing post event analysis and re-designing the BHA for a subsequent well, the redesigned BHA including at least one of different or additional wear band placement, replacement of heavy weight drill pipe with drill collars or vice versa, or changing a distance between components such that the HFTO node is located away from a sensitive component.
Dependencies are inferred from the claim text.