Piezoelectric Downhole Compressibility Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for measuring the compressibility of reservoir fluids in situ are unavailable, leading to uncertainties due to pressure and temperature changes during sample transfer to the surface, which can cause irreversible alterations and component separations.
Innovation Solution
A downhole tool with a chamber containing or coupled to a piezoelectric material is used to measure fluid compressibility by applying a voltage to alter the material's shape, changing the chamber volume and measuring the resulting pressure change, allowing for in situ determination of fluid compressibility using equations like ΔP = α(2d31 + d33)E3βT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reservoir fluid samples are brought to the surface for compressibility measurement, then measurement capability is achieved, but pressure and temperature changes during transfer cause component separations and irreversible alterations of the fluid
Solution Approach 1:
A diaphragm is introduced as an intermediary barrier that separates the reservoir fluid from the piezoelectric material while still allowing transmission of mechanical stress. This enables the piezoelectric material to sense fluid pressure changes without direct contact, thus preventing contamination or alteration of the fluid composition while maintaining measurement capability
Solution Approach 2:
The patent replaces traditional mechanical pressure sensing systems with a piezoelectric sensing system. The piezoelectric material converts pressure-induced mechanical stress directly into electrical signals, enabling precise compressibility measurements without requiring physical manipulation or transfer of the fluid sample
2Measurement precision
If piezoelectric material is placed inside the fluid chamber for direct measurement, then measurement sensitivity is improved, but the material may contaminate or alter the fluid sample
Solution Approach 1:
The diaphragm serves as a mediator that transmits mechanical stress from the fluid to the piezoelectric material while preventing direct contact between the two. This allows the piezoelectric material to be positioned close to the fluid for high sensitivity measurements without compromising fluid sample integrity
3Measurement precision
If traditional surface-based compressibility measurement methods are used, then measurement capability is achieved, but time-consuming sample transfer and potential fluid alteration occur
Solution Approach 1:
The downhole tool performs compressibility measurements in situ before the fluid sample is brought to the surface. By conducting the measurement preliminary to sample retrieval, the system eliminates time-consuming transfer processes and prevents any potential fluid alterations that could occur during transport
Solution Approach 2:
The patent implements an automated piezoelectric sensing system that operates downhole, replacing manual surface-based measurement procedures. This substitution enables immediate in situ measurements, dramatically reducing the time required for compressibility determination
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
This method provides accurate, in situ measurements of fluid compressibility, reducing uncertainties associated with surface measurements and avoiding irreversible fluid alterations, while enabling the inference of other fluid characteristics like bulk density and specific heat ratio.
Implementation Method 1
a piezoelectric material... When a voltage is applied to the piezoelectric material, the piezoelectric material contracts in directions orthogonal to poling directions, but expands along its vertical poling direction, thereby changing its volume
Implementation Method 2
A pressure sensor that measures the pressure in the chamber is provided. The change in pressure resulting from the change in bulk volume (or the change in fluid volume) is then related to the compressibility of the fluid
Data Source
AI summary
Methods and apparatus are provided for the measurement of the compressibility of reservoir fluid. A piezoelectric material is coupled to a wall of a fluid chamber. Compressibility is derived from measured pressure changes to the fluid resulting from volumetric changes to the fluid chamber imposed by the mechanical strain of the piezoelectric material resulting from an applied electric field.