Measurement tool and method of use

A method of determining the density and the viscosity of a fluid within a pipe, the method comprising the steps of:

• {i} providing a measurement tool having a resilient pipe with a substantially uniform cross-section along its length, the pipe carrying an exciter at the longitudinal centre of the pipe, the exciter being connected to a signal generator, the tool also having a detector located at the longitudinal centre of the pipe;
• {ii} issuing a first alternating electrical signal from the signal generator to the exciter so as to impart transverse oscillations into the pipe substantially at its resonant frequency for transverse oscillations;
• {iii} stopping the first electrical signal to the exciter;
• {iv} measuring the frequency of the transverse oscillations,
• {v} using the frequency of the transverse oscillations to determine the density of the fluid,
• {vi} issuing a second alternating electrical signal from the signal generator to the exciter so as to impart rotational oscillations into the pipe substantially at its resonant frequency for rotational oscillations;
• {vii}stopping the second electrical signal to the exciter;
• {viii} measuring the decay curve of the rotational oscillations, and
• {ix} using the decay curve of the oscillations to determine the viscosity of the fluid.

A measurement tool comprising a pipe;

• the pipe being resilient and having a substantially uniform cross-section along its length;
• an exciter carried by the pipe and being located at the longitudinal centre of the pipe;
• a signal generator connected to the exciter, the signal generator and exciter being adapted to impart transverse and rotational oscillations to the pipe;
• a detector located at the longitudinal centre of the pipe, the detector being adapted to detect the transverse oscillations and the rotational oscillations of the pipe;
• and
• means to measure the resonant frequency of the transverse oscillations of the pipe and to determine the density of a fluid within the pipe from the resonant frequency of the transverse oscillations, and to measure the decay curve of rotational oscillations of the pipe and to determine the viscosity of the fluid within the pipe from the decay curve of the rotational oscillations,
• the means to measure the resonant frequency of the transverse oscillations of the pipe being adapted to measure the resonant frequency whilst the signal generator and exciter are not imparting transverse oscillations to the pipe.