Downhole test signals for identification of operational drilling parameters

Patent metadata

Field	Value
Publication number	US-2016348493-A1
Application number	US-201514725621-A
Country	US
Kind code	A1
Filing date	May 29, 2015
Priority date	May 29, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

A method for selecting drilling parameters for drilling a borehole penetrating the earth with a drill string includes: varying a frequency of an excitation force applied to the drill string using an excitation device controlled by a drill string controller and measuring vibration-related amplitudes of the drill string due to the applied excitation force using a vibration sensor to provide amplitude measurements. The method further includes determining one or more modal properties comprising one or more eigenfrequencies of the drill string using the amplitude measurements and selecting drilling parameters that apply an excitation force at a frequency that avoids a selected range of frequencies that bound the one or more eigenfrequencies.

First claim

What is claimed is:

1 . A method for selecting drilling parameters for drilling a borehole penetrating the earth with a drill string, the method comprising:
varying a frequency of an excitation force applied to the drill string using an excitation device controlled by a drill string controller; measuring vibration-related amplitudes of the drill string due to the applied excitation force using a vibration sensor to provide amplitude measurements; determining with a processor one or more modal properties comprising one or more eigenfrequencies of the drill string using the amplitude measurements; and selecting drilling parameters that apply an excitation force at a frequency that avoids a selected range of frequencies that bound the one or more eigenfrequencies using the processor.

2 . The method according to claim 1 , wherein the excitation force comprises at least one selection from a group consisting of torque, impact force, and position displacement.

3 . The method according to claim 1 , wherein the vibration-related amplitudes are measured in at least one selection from a group consisting of time domain and frequency domain.

4 . The method according to claim 1 , wherein the one or more modal properties further comprise modal shape and/or modal damping.

5 . The method according to claim 1 , further comprising drilling the borehole with a drilling rig using the selected drilling parameters.

6 . The method according to claim 1 , wherein the excitation device comprises a mud-motor and varying a frequency comprises varying a flow rate of drilling fluid through the drill string.

7 . The method according to claim 6 , wherein varying a flow rate comprises varying at least one of a drilling fluid pump speed and a drilling fluid flow valve.

8 . The method according to claim 1 , further comprising keeping one or more drilling parameters not associated with the excitation force applied to the drill string constant while the frequency of the excitation force is varied.

9 . The method according to claim 1 , wherein the sensor is disposed in a bottomhole assembly of the drill string or on the drill string at a location other than in the bottomhole assembly.

10 . The method according to claim 9 , wherein the sensor comprises a plurality of sensors.

11 . The method according to claim 1 , wherein the sensor is disposed at a location that is not a node of a modal shape of the drill string.

12 . The method according to claim 11 , further comprising:
constructing a mathematical model of the drill string comprising dimensions and mass distribution of the drill string; analyzing a response of the mathematical model to an excitation stimulus to provide the modal shape of the drill string; and determining a location of one or more nodes of the modal shape.

13 . The method according to claim 12 , wherein the mathematical model comprises a shape and dimensions of the borehole and the drill string being disposed in the borehole.

14 . The method according to claim 13 , further comprising calculating a ratio of vibration amplitude at a location of the vibration sensor to the maximum vibration of the drill string at another location using the mathematical model.

15 . The method according to claim 14 , calculating the maximum vibration amplitude of the drill string using the ratio and the vibration amplitude measurements obtained by the vibration sensor.

16 . The method according to claim 1 , wherein the excitation device is located at a location that can excite the drill string.

17 . The method according to claim 16 , wherein the excitation device comprises a plurality of excitation devices and the excitation devices are excited simultaneously, sequentially or some combination thereof.

18 . A method for selecting drilling parameters for drilling a borehole penetrating the earth with a drill string, the method comprising:
constructing a mathematical model of the drill string comprising dimensions and mass distribution of the drill string; analyzing a response of the mathematical model to an excitation stimulus to provide a modal shape of the drill string; determining a location of one or more nodes of the modal shape; disposing a plurality of vibration sensors at locations along the drill string that are not nodes of the modal shape; varying a frequency of excitation forces applied to the drill string using a plurality of excitation devices, the excitation forces being applied simultaneously, sequentially or some combination thereof; measuring amplitudes of vibrations of the drill string due to the applied excitation forces using the plurality of vibration sensors to provide amplitude measurements; determining with a processor one or more modal properties comprising one or more eigenfrequencies of the drill string using the amplitude measurements; applying a correction factor as determined by the analysis of the mathematical model to the measured amplitudes to determine a maximum amplitude of vibration of the drill string; selecting drilling parameters that apply an excitation force at a frequency that avoids a selected range of frequencies that bound the one or more eigenfrequencies using the processor; and transmitting the selected drilling parameters to a drill string controller configured to control the drill string in accordance with the selected drilling parameters.

19 . An apparatus for selecting drilling parameters for drilling a borehole penetrating the earth with a drill string, the apparatus comprising:
an excitation device configured to vary a frequency of an excitation force applied to the drill string; a drill string controller configured to operate the excitation device in order to vary the frequency of the excitation force; a vibration sensor configured to measure amplitudes of vibrations of the drill string due to the applied excitation force to provide amplitude measurements that are in a time domain and/or a frequency domain; and a processor configured to (i) determine one or more modal properties comprising one or more eigenfrequencies of the drill string using the amplitude measurements, (ii) select drilling parameters that apply an excitation force at a frequency that avoids a selected range of frequencies that bound the one or more eigenfrequencies and (iii) transmit the selected drilling parameters to a drill string controller configured to control the drill string in accordance with the selected drilling parameters.

20 . The apparatus according to claim 19 , wherein the processor is further configured to:
construct a mathematical model of the drill string comprising dimensions and mass distribution of the drill string; analyze a response of the mathematical model to an excitation stimulus to provide the modal shape of the drill string; and determine a location of one or more nodes of the modal shape.

21 . The apparatus according to claim 20 , wherein a location of the vibration sensor is not at a node of the modal shape of the drill string.

22 . The apparatus according to claim 21 , wherein the vibration sensor comprise a plurality of vibration sensors disposed at locations along the drill string that are not nodes of the modal shape.

Assignees

• Hohl Andreas
• Baker Hughes Inc

Inventors

• Hohl Andreas

Classifications

• E21B47/007

  Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09) · CPC title

• E21B44/04 Primary

  in response to the torque of the drive {; Measuring drilling torque (E21B44/06 takes precedence; measuring stresses in a well bore pipe E21B47/007)} · CPC title

• F04C2270/86

  Detection · CPC title

• E21B4/02

  Fluid rotary type drives · CPC title

• F04C14/08

  characterised by varying the rotational speed · CPC title