Measuring a dew point

Patent metadata

Field	Value
Publication number	US-9823223-B2
Application number	US-201514847012-A
Country	US
Kind code	B2
Filing date	Sep 8, 2015
Priority date	Sep 25, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A sensor including a vibrating wire is used to measure a dew point of a fluid.

First claim

What is claimed is:

1. A system comprising:
a sensor device comprising:
an electrically conductive wire immersible in a fluid in a retrograde condensate;
support structures to hold the wire, wherein the wire when energized results in vibratory movement of the wire;
an activator to excite the wire to cause vibration of the wire; and
a measurement module to measure signals representative of the vibratory movement of the wire, the measurement module is to output measured signals after the excitation of the wire has been removed; and

at least one processor to determine a dew point of the fluid based on the measured signals from the sensor device, the determining the dew point of the fluid comprises determining values of a decrement relating to motion of the wire across different pressures and identifying a pressure at which a slope of the values of the decrement changes sign.

2. The system of claim 1 , wherein the dew point is a pressure at which condensation of the fluid starts to occur.

3. A method for determining a dew point of a fluid in a retrograde condensate, comprising:
providing a sensor including an outer housing defining a chamber and a vibrating wire in the chamber, wherein the vibrating wire is held in tension;
introducing the fluid into the chamber, wherein the fluid is in contact with the vibrating wire;
driving an electrical current into the vibrating wire in a presence of a magnetic field, to create an oscillating force for a vibratory motion of the vibrating wire, wherein the vibratory motion of the vibrating wire is responsive to accumulation of dew droplets on the vibrating wire that lowers a resonant frequency and increases damping of the vibrating wire;
reducing a pressure in the chamber to obtain the measured vibratory motion at different pressures;
determining values of a parameter across the different pressures, wherein the parameter is a decrement relating to the vibratory motion of the vibrating wire; and
determining the dew point of the fluid by identifying a pressure at which a slope of the values of the decrement changes sign.

4. The article of claim 3 , wherein determining the dew point of the fluid comprises determining a pressure of the fluid at which condensation starts to occur.

5. The article of claim 3 , wherein the measured vibratory motion represents a transient response of the vibrating wire in response to excitation of the vibrating wire with the electrical current in a presence of the magnetic field followed by removal of the excitation.

6. An article comprising at least one non-transitory machine-readable storage medium storing instructions that upon execution cause a system to:
introduce a fluid in a retrograde condensate into a vibrating wire viscometer that includes a vibrating wire, wherein the fluid is in contact with vibrating wire;
drive an electrical current into the vibrating wire in a presence of a magnetic field, to create an oscillating force for a vibratory motion of the vibrating wire;
measure a vibratory motion of the vibrating wire from the vibrating wire viscometer at different pressures;
determining values of a parameter across the different pressures, wherein the parameter is a decrement relating to the vibratory motion of the vibrating wire; and
determine a dew point of the fluid by identifying a pressure at which a slope of the values of the decrement changes sign.

Assignees

• Schlumberger Technology Corp

Inventors

• Harrison Christopher
• Fukagawa Shunsuke
• Sullivan Matthew T
• Smythe Elizabeth Jennings
• Meier John

Classifications

• G01N2291/02818

  Density, viscosity · CPC title

• G01N29/036 Primary

  by measuring frequency or resonance of acoustic waves · CPC title

• G01N11/16

  by measuring damping effect upon oscillatory body · CPC title

• G01N2291/014

  Resonance or resonant frequency · CPC title

• G01N2291/02845

  Humidity, wetness · CPC title