Acoustic Fluid Density Determination for Complex Flow Cells
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Solution Overview
Problem
Existing methods for downhole fluid sampling and analysis, particularly for measuring fluid density and viscosity, face challenges such as limited durability for long logging jobs and the need for backup sensors, highlighting the requirement for more reliable and efficient acoustic techniques.
Innovation Solution
A method involving the collection of data sets with corresponding sound speed, temperature, pressure, and density values for live crude oil samples, followed by the generation of multinomial expansions and development of a correlation prediction function. This method includes acoustically analyzing the sample fluid inside an evaluation flow cell to estimate its density and optionally its viscosity and brine salinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric tuning fork is used to measure fluid density and viscosity, then real-time measurement is achieved, but the sensor durability is limited for long logging jobs
Solution Approach 1:
The patent replaces the mechanical piezoelectric tuning fork with an acoustic resonance system using a transducer and flow cell. The transducer generates acoustic waves that resonate at frequencies dependent on fluid density and viscosity, eliminating the mechanical wear and failure modes of the tuning fork while maintaining real-time measurement capability.
Solution Approach 2:
The invention changes the measurement approach from direct mechanical vibration (tuning fork) to acoustic resonance frequency analysis. By measuring the resonant frequency and decay characteristics of acoustic waves in the fluid, the system achieves equivalent measurement precision with improved reliability for extended logging operations.
2Reliability
If a backup sensor is carried for long logging jobs, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The acoustic resonance measurement system performs multiple functions with a single sensor configuration. It simultaneously measures fluid density, viscosity, and other properties by analyzing different aspects of the acoustic resonance response, eliminating the need for multiple backup sensors while maintaining measurement reliability.
Solution Approach 2:
The system uses the fluid itself as part of the measurement medium. The acoustic waves propagate through the fluid sample in the flow cell, and the fluid's own acoustic properties (density, viscosity) directly determine the resonance characteristics, eliminating the need for separate calibration sensors or backup measurement systems.
3Adaptability or versatility
If acoustic analysis is performed in a geometrically complex flow cell, then downhole fluid analysis is enabled, but measurement accuracy is affected by the complex geometry
Solution Approach 1:
The patent introduces a computational model as an intermediary between the acoustic measurement and the fluid property determination. The model accounts for the specific geometric characteristics of the flow cell and translates the acoustic resonance data into accurate fluid density and viscosity values, correcting for geometry-induced measurement variations.
Solution Approach 2:
The system performs preliminary characterization of the flow cell geometry and acoustic response using known reference fluids. This preliminary calibration establishes the relationship between acoustic measurements and fluid properties for that specific geometry, enabling accurate measurements without requiring simple flow cell designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed method effectively estimates fluid density and viscosity, achieving high accuracy and reliability, even in real-time downhole conditions, thereby addressing the limitations of existing technologies.
Implementation Method 1
the transducer is configured to generate an acoustic wave that propagates through the fluid in the flow cell and that reverberates within the flow cell
Implementation Method 2
obtaining a value of sound speed of the sample fluid by acoustically analyzing the sample fluid
Implementation Method 3
the reverberation of the acoustic wave within the flow cell depends on a density of the fluid and a viscosity of the fluid
Implementation Method 4
obtaining a value of sound speed of the sample fluid by acoustically analyzing the sample fluid inside of an evaluation flow cell
Data Source
AI summary
A method of wellbore operations for identifying sample fluid density and viscosity. The sample fluid is collected from a formation, and acoustically irradiated in a flow cell. Acoustic reflections are collected and analyzed to obtain a sound speed of the sample fluid and a value for the slope of the decay rate of an acoustic signal reverberating within a wall of the flow cell, which is in physical contact with the transducer. The fluid temperature, pressure, and the sound speed of the flow cell material may also be measured. The sample fluid density and viscosity are estimated from equations derived by a regression performed on a set of training data, which was generated from testing the flow cell with fluids having known densities, viscosities, or other characteristics.