VIBRATING WIRE VISCOMETERS
First Claim
1. An apparatus to determine the viscosity of a downhole fluid, comprising:
- a wire to be immersed in a downhole fluid, to vibrate when an alternating current is applied to the wire within a magnetic field, and to generate an electromotive force when vibrating within the magnetic field, the wire comprising a first resistance;
a nulling circuit coupled to the wire, wherein the nulling circuit comprises a second resistance that is selectable to be substantially equal to the first resistance; and
an analyzer coupled to the wire and the nulling circuit to determine the first resistance, the second resistance, and a viscosity of the downhole fluid based on the first and second resistances, at least one characteristic of the wire, and the electromotive force.
1 Assignment
0 Petitions
Accused Products
Abstract
Vibrating wire viscometers are disclosed. An example apparatus to determine the viscosity of a downhole fluid is described, the apparatus including a wire to be immersed in a downhole fluid, to vibrate when an alternating current is applied to the wire within a magnetic field, and to generate an electromotive force when vibrating within the magnetic field, the wire comprising a first resistance. The apparatus further includes a nulling circuit coupled to the wire, wherein the nulling circuit comprises a second resistance that is selectable to be substantially equal to the first resistance, and an analyzer coupled to the wire and the nulling circuit to determine the first resistance, the second resistance, and a viscosity of the downhole fluid based on the first and second resistances, at least one characteristic of the wire, and the electromotive force.
-
Citations
20 Claims
-
1. An apparatus to determine the viscosity of a downhole fluid, comprising:
-
a wire to be immersed in a downhole fluid, to vibrate when an alternating current is applied to the wire within a magnetic field, and to generate an electromotive force when vibrating within the magnetic field, the wire comprising a first resistance; a nulling circuit coupled to the wire, wherein the nulling circuit comprises a second resistance that is selectable to be substantially equal to the first resistance; and an analyzer coupled to the wire and the nulling circuit to determine the first resistance, the second resistance, and a viscosity of the downhole fluid based on the first and second resistances, at least one characteristic of the wire, and the electromotive force. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An apparatus to determine the viscosity of a downhole fluid, comprising:
-
a wire to be immersed in a downhole fluid, to vibrate when an alternating current is applied to the wire within a magnetic field, and to generate an electromotive force when vibrating within the magnetic field, the wire comprising a resistance; a nulling circuit coupled to the wire to generate an offset signal; and an analyzer coupled to the wire and the nulling circuit to determine an offset voltage based on the resistance, to configure the offset signal based on the offset voltage, and to determine a viscosity of the downhole fluid based on the resistance, the offset signal, at least one characteristic of the wire, and the electromotive force. - View Dependent Claims (11, 12, 13)
-
-
14. A method to measure a viscosity of a downhole fluid, comprising:
-
immersing a wire in a downhole fluid; determining at least one of a resistance or an offset voltage on the wire; configuring a nulling circuit to compensate for the resistance or the offset voltage; applying an alternating current to the wire to cause the wire to vibrate a resonance frequency and generate an electromotive force while the wire is subjected to a magnetic field; and determining a voltage on the wire during vibration of the wire by determining a difference between a first signal generated by the alternating current and the magnetic field at the wire and a second signal generated by the nulling circuit. - View Dependent Claims (15, 16, 17, 18, 19, 20)
-
Specification