CHANGING SET POINTS IN A RESONANT SYSTEM

• US 20160139615A1
• Filed: 06/26/2014
• Published: 05/19/2016
• Est. Priority Date: 06/27/2013
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Canada
• Inventors: JEFFRYES, Benjamin Peter, COOK, John, GAHLINGS, Steven
• Granted Patent: US 10,409,300 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E21B 43/128 Adaptation of pump systems with down-hole electric drives
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
• CPC Class Codes: E21B 47/00 Survey of boreholes or wells monitoring pressure or flow of drilling fluid E21B21/08
• CPC Class Codes: E21B 47/007 Measuring stresses in a pipe string or casing for locating blocked portions of pipes E21B47/09
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05D 19/02 characterised by the use of electric means

Abstract

A method for changing a set point of a system where period of a dominant resonance of the system is determined, a change profile for the set point change is processed; a time period for the set point change based on the period of the dominant resonance in order to minimize excitation of the dominant resonance is also processed; and the set point change is actioned according to the processed change profile and the time period.

Claims

1. A method for changing a set point of a system in a borehole, comprising:

determining the period of a dominant resonance of the system;

processing a change profile for the set point change;

determining a time period for the set point change based on the period of the dominant resonance in order to minimize excitation of the dominant resonance; and

performing the set point change according to the change profile and the time period.

2. The method of claim 1, wherein the time period is comprises a multiple of the period of the dominant resonance.

3. The method of claim 2, wherein the change profile is comprises a linear change profile, and the time period is an integer multiple of the period of the dominant resonance.

4. The method of claim 2, wherein the time derivative of the change profile has a half-period of a sine-wave, and the time period is an integer-plus-a-half multiple of the period of the dominant resonance.

5. The method of claim 1, wherein the change profile is symmetric about the mid-time of the change.

6. The method of claim 1, wherein the determination of the time period for the set point change is performed by taking the Fourier transform of the time derivative of the change profile.

7. The method of claim 1, wherein the borehole system comprises a drillstring.

8. The method of claim 1, wherein the borehole system comprises a wireline.

9. The method of claim 1, wherein the borehole system comprises an electro-submersible pump.

10. A computer program comprising code which, when run on a computer, causes the computer to perform the method of claim 1.

11. (canceled)

12. A control system for changing a set point of a system in a borehole, comprising:

a computer processor configured to;

determine the period of a dominant resonance of the system;

process a change profile for the set point change from the sensed properties; and

determine a time period for the set point change based on the period of the dominant resonance in order to minimize excitation of the dominant resonance; and

a controller configured to control the system to perform the set point change according to the change profile and the time period.

13. The control system of claim 12, further comprising one or more sensors to sense properties of the system and/or the borehole, the determination of the period of the dominant resonance of the system and/or the processing of the change profile being based on the sensed properties.

14. A rig or a tool having the control system of claim 13.

15. The control system of claim 12, wherein the system comprises a managed pressure drilling system.

16. The control system of claim 12, wherein the system comprises a drilling system

17. An automated system for operating one or more systems in a borehole, wherein the automated systems comprises the control system of claim 12.