Method to predict, illustrate, and select drilling parameters to avoid severe lateral vibrations

摘要

A method for estimating drilling parameters for drilling a borehole in the earth includes: drilling the borehole with a drill string having a mud motor and a drill bit; constructing a mathematical model of a system including the drill string, the mud motor, and a borehole geometry; calculating a mud motor lateral excitation force imposed on the drill string by the mud motor for one or more combinations of drill string rotational speed and mud motor rotational speed; calculating lateral motion of the drill string and a force imposed on the drill string at positions along the drill string for the one or more of combinations using the model and the excitation force; selecting a range of combinations of drill string rotational speed and mud motor rotational speed that result in the force imposed upon the drill string being less than a threshold value; and displaying the range of combinations.

主权项

1. A method for estimating drilling parameters of a drill rig for drilling a borehole in an earth material, the method comprising:
drilling the borehole with the drilling rig in operable communication with a drill string having a mud motor and a drill bit, the drill rig being receptive to adjustable rotational speed of the drill string and adjustable rotational speed of the mud motor; constructing a mathematical model of a system comprising the drill string, the mud motor, and a geometry of the borehole using a processor, the model comprising dimensions, mass distribution, material density, and material stiffness; calculating a mud motor lateral excitation force imposed on the drill string by the mud motor for one or more combinations of drill string rotational speed and mud motor rotational speed using the processor; calculating, with the processor, lateral motion of the drill string and a value of a force related parameter imposed on the drill string at a plurality of positions along the drill string for the one or more of combinations of drill string rotational speed and mud motor rotational speed using the mathematical model and the mud motor lateral excitation force; selecting a range of combinations of drill string rotational speed and mud motor rotational speed that result in the value of the force related parameter imposed upon the drill string being less than a threshold value using the processor, wherein the drilling parameters comprise drill string rotational speed and mud motor rotational speed; and displaying the range of combinations to a user using a display.