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.
Claims21
A method for predicting a position of a node for vibration in a drill string, comprising:
- accessing a model that is based on vibration frequency and distance relative to a reference location on the drill string;
- and
- using measured vibration frequency as input to the model to determine a location of a node in the drill string.
A method comprising:
- accessing a model that is based on vibration frequency and distance relative to a reference location on a bottomhole assembly;
- based on a design of the bottomhole assembly, using the model to predict vibration frequency in the bottomhole assembly.
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 bottomhole assembly to identify a position of an HFTO node in the BHA;
- when the 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 node is at a contact point in a lateral of the drilled wellbore, back reaming or sending a recommendation to back ream;
- and
- when the node is in a motor of the BHA, changing drilling parameters or sending a recommendation to change drilling parameters.
Dependencies are inferred from the claim text.