Increased drill bit or lower bha inertia for reducing hfto
AssigneeSchlumberger Technology Corporation
InventorsAshley Bernard Johnson, David Scott
Life of this patent
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Abstract
A bottom hole assembly (BHA) configured for drilling a subterranean wellbore, the BHA including a drill bit for drilling the wellbore; a rotary steerable tool for controlling direction of drilling by the drill bit; and a sleeve operably coupled between the rotary steerable tool and the drill bit, wherein the sleeve is configured to increase a moment of inertia of the BHA by at least 20%.
Claims13
A lower bottom hole assembly (BHA) configured for drilling a subterranean wellbore, the lower BHA comprising:
- a drill bit for drilling the wellbore;
- and
- a sleeve operably coupled to the drill bit, wherein the sleeve is configured to increase a moment of inertia of the lower BHA to mitigate high frequency torsional oscillation (HFTO) experienced by the lower BHA.
A method for reducing high-frequency torsional oscillations (HFTO) during a downhole drilling operation that drills a wellbore, the method comprising:
- estimating an HFTO propensity of a lower bottom hole assembly (BHA) that includes a drill bit for drilling the wellbore, wherein the HFTO propensity of the lower BHA is estimated using a model that relates the HFTO propensity to at least a rock strength of a subterranean formation, a radius or diameter of the borehole, and a length of the lower BHA;
- comparing the estimated HFTO propensity with an HFTO propensity threshold;
- and
- when the estimated HFTO propensity exceeds the HFTO propensity threshold, use the model to modify the lower BHA in order to reduce the estimated HFTO propensity to a value below the HFTO propensity threshold.
Dependencies are inferred from the claim text.