Characterizing lubricant oil degradation using fluorescence signals

Patent metadata

Field	Value
Publication number	US-10317388-B2
Application number	US-201816056020-A
Country	US
Kind code	B2
Filing date	Aug 6, 2018
Priority date	Apr 26, 2016
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

Methods, systems, and apparatus to diagnose lubrication oil deterioration. In one aspect, a method includes irradiating a lubrication oil sample with a light beam to emit a light-induced fluorescence, detecting and processing the light-induced fluorescence signal to determine a temporal variation of a fluorescence intensity, identifying a steady state of the light-induced fluorescence signal, processing the temporal variation of the fluorescence intensity to determine a lubrication oil parameter, and correlating the oil parameter to a calibration curve to diagnose the lubrication oil deterioration.

First claim

What is claimed is:

1. A method to diagnose lubrication oil deterioration, the method comprising:
generating a continuous wave collimated light beam;
chopping the continuous wave collimated light beam into a plurality of step light beams, each step light beam having a constant intensity for a particular time interval;
irradiating a fresh lubrication oil sample obtained from a hydrocarbon well equipment with the plurality of step light beams such that a first light-induced fluorescence is emitted from the fresh lubrication oil sample in response to irradiation by each step light beam;
detecting a first light-induced fluorescence signal from the fresh lubrication oil sample;
irradiating a deteriorated lubrication oil sample obtained from the hydrocarbon well equipment with the plurality of step light beams such that a second light-induced fluorescence is emitted from the deteriorated oil sample in response to irradiation by each step light beam;
detecting a second light-induced fluorescence signal from the deteriorated lubrication oil sample;
determining a lubrication oil parameter from the first light-induced fluorescence signal and from the second light-induced fluorescence signal, wherein each of the lubrication oil parameters are associated to at least one of an oil viscosity of the respective lubrication oil sample, a damping ratio of the respective fluorescence signal, and or an undamped natural frequency of the respective fluorescence signal; and
determining an amount of lubrication oil deterioration of the deteriorated lubrication oil sample by correlating the lubrication oil parameter from the first light-induced fluorescence signal and from the second light-induced fluorescence signal to a calibration curve.

2. The method of claim 1 , wherein determining the lubrication oil parameter comprises determining a temporal variation of a fluorescence intensity from the light-induced fluorescence-signal.

3. The method of claim 2 , wherein determining the lubrication oil parameter comprises determining a steady-state of the light-induced fluorescence-signal from the temporal variation of the fluorescence intensity.

4. The method of claim 3 , wherein determining the lubrication oil parameter comprises determining the lubrication oil parameter from the steady-state of the light-induced fluorescence-signal.

5. The method of claim 2 , wherein the fluorescence intensity is represented as a second order dynamic system corresponding to one of an over-damped oscillator with a damping factor larger than 1 or an under-damped oscillator with a damping ratio smaller than 1.

6. The method of claim 1 , further comprising collecting the lubrication oil sample from the hydrocarbon well equipment.

7. The method of claim 1 , further comprising guiding the light beam at an acute angle on a front surface of a container holding the lubrication oil sample.

8. The method of claim 1 , further comprising filtering the light-induced fluorescence signal.

9. The method of claim 1 , further comprising capturing the light-induced fluorescence signal by a fast photodiode.

10. The method of claim 1 , further comprising:
comparing the oil parameter to previously measured oil parameter to determine an oil deterioration rate; and
determining an estimate of a useful remaining lifetime of the hydrocarbon well equipment associated to the lubrication oil sample based on the oil deterioration rate, wherein the hydrocarbon well equipment is in use in a hydrocarbon-producing well during determining the estimate of the useful remaining lifetime of the hydrocarbon well equipment.

11. The method of claim 10 , wherein the hydrocarbon well equipment is a submersible pump configured to pump fluid uphole from the hydrocarbon-producing well and wherein the submersible pump is disposed within the hydrocarbon-producing well.

12. The method of claim 1 , wherein the light beam is generated by a laser source.

13. A system, comprising:
a light beam generator configured to generate a continuous wave collimated light beam;
a chopper configured to chop the continuous wave collimated light beam into a plurality of step laser beams, each step laser beam having a constant intensity for a particular time interval;
a container configured to hold a lubrication oil sample;
an optical equipment configured to guide the plurality of step laser beams to a face of the container;
a fast photodiode configured to detect light-induced fluorescence signal from the lubrication oil sample in response to irradiation by the plurality of step light beams; and
a hardware processor interoperably coupled with a memory and configured to:
detect a first light-induced fluorescence signal from a fresh lubrication oil sample obtained from a hydrocarbon well equipment;
detect a second light-induced fluorescence signal from a deteriorated lubrication oil sample obtained from the hydrocarbon well equipment;
determine a lubrication oil parameter from the first light-induced fluorescence signal and from the second light-induced fluorescence signal, wherein each of the lubrication oil parameters are associated to at least one of an oil viscosity of the respective lubrication oil sample, a damping ratio of the respective fluorescence signal, and an undamped natural frequency of the respective fluorescence signal; and
determine an amount of lubrication oil deterioration of the deteriorated lubrication oil sample by correlating the lubrication oil parameter from the first light-induced fluorescence signal and from the second light-induced fluorescence signal to a calibration curve.

Assignees

• Saudi Arabian Oil Co

Inventors

• Hegazi Ezzat
• Cunningham Vincent
• Nour Maha

Classifications

• G01J3/4406

  Fluorescence spectrometry · CPC title

• G01N33/2888 Primary

  Lubricating oil characteristics, e.g. deterioration (lubricating properties G01N33/30) · CPC title

• G01N21/6408

  with measurement of decay time, time resolved fluorescence · CPC title

• G01N2201/129

  Using chemometrical methods · CPC title

• G01N21/6402

  Atomic fluorescence; Laser induced fluorescence · CPC title