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US 5,313,829 AGranted
Method of determining drillstring bottom hole assembly vibrations
AssigneeAtlantic Richfield Company
InventorsPaul R. Paslay, Yih-Min Jan
Life of this patent
Estimating the term…
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AssigneeAtlantic Richfield Company
InventorsPaul R. Paslay, Yih-Min Jan
Estimating the term…
Lateral vibrations of drillstring bottom hole assemblies are confirmed by sensing longitudinal and torsional accelerations or displacements of the drillstring at or near its top end during rotation and determining the lateral critical speed and displacement of the drillstring from the mode shape of the bottom hole assembly which occurs during forward synchronous whirl and longitudinal shortening of the bottom hole assembly resulting from such whirl. Lateral motion of the bottom hole assembly, while drilling, is estimated based on longitudinal and torsional measurements at the top of the drillstring. Radial displacement of the bottom hole assembly due to impacting of the borehole wall imparts a torsional impulse which, together with considerable radial motion, is repeated each revolution. The lateral or radial motion causes a small axial motion to develop in the bottom hole assembly which results in an axial force on and axial shortening of the drillstring which varies once per revolution.
A method for determining the occurrence of whirling of at least a portion of an elongated drillstring during rotation of said drillstring in a well bore, said method comprising the steps of:
A method for determining the occurrence of whirling of at least a portion of an elongated drillstring during rotation of said portion of said drillstring in a well bore, said portion of said drillstring including a bottom hole assembly comprising a bit connected to one end of a first member and a second member connected to said first member at the opposite end of said first member, said method comprising the steps of:
A method for determining the occurrence of whirling of at least a portion of an elongated drillstring during rotation of said drillstring in a well bore, said method comprising the steps of:
A method for determining the occurrence of whirling of at least a portion of an elongated drillstring during rotation of said drillstring in a well bore, said method comprising the steps of:
Dependencies are inferred from the claim text.