Downhole Fluid Volume Estimation via Over-Pressurization
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Solution Overview
Problem
Current methods for estimating fluid component volumes in downhole fluid analysis are inaccurate due to differences in pressure and temperature between measurement points and sample chambers, leading to errors in volume fractions, especially when dealing with highly compressible gases and liquids with different velocities and phase equilibria.
Innovation Solution
The method involves measuring fluid characteristics at two times, first when the sample chamber is full and second after over-pressurizing it with a supplemental volume, using equations of state to calculate the volumes of compressible and non-compressible fluid components, accounting for pressure and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluid volume is measured using conventional single-time measurement methods, then the measurement process is simple, but the measurement precision is poor due to pressure and temperature changes affecting compressible fluids
Solution Approach 1:
The patent applies preliminary action by measuring fluid characteristics at a first time before pressure changes occur, then using this baseline measurement to calculate component volumes after over-pressurization. This preliminary measurement captures the fluid state under initial conditions, enabling accurate decomposition into compressible and non-compressible components even after pressure changes affect the final state.
Solution Approach 2:
The patent uses feedback by measuring fluid characteristics at both a first time (before over-pressurization) and a second time (after over-pressurization), then using the difference between these measurements to calculate fluid component volumes. The second measurement provides feedback on how the fluid state changed due to pressure, enabling correction for compressibility effects.
2Reliability
If single measurement method is used, then the operation is simple, but the reliability is low due to inability to account for compressibility and phase changes
Solution Approach 1:
The patent performs preliminary measurement of fluid characteristics before over-pressurization to establish a baseline state. This preliminary action captures the fluid composition and properties under initial pressure conditions, which is essential for reliably determining component volumes after the fluid state changes due to compressibility and phase transitions.
Solution Approach 2:
The patent implements feedback by comparing fluid characteristic measurements taken before and after over-pressurization. This feedback mechanism allows the system to account for pressure-induced changes in fluid density and phase, thereby improving the reliability of fluid component volume calculations despite the added operational complexity.
3Measurement precision
If conventional measurement methods are used, then the device complexity is low, but the measurement precision deteriorates under varying pressure and temperature conditions
Solution Approach 1:
The patent applies preliminary action by capturing fluid characteristic data before pressure changes occur. This baseline measurement is stored and later used in conjunction with post-pressurization measurements to calculate accurate component volumes, thereby improving measurement precision without requiring complex real-time compensation hardware.
Solution Approach 2:
The patent uses feedback by measuring fluid properties at two different pressure states and using the difference to calculate compressible and non-compressible fluid volumes. This feedback approach allows the system to mathematically compensate for pressure and temperature effects, improving precision without adding complex physical compensation mechanisms.
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 approach provides accurate estimates of fluid component volumes, even in situations with different phase velocities and at low pressures, by accounting for compressibility and phase changes, thus improving the precision of fluid characterization.
Implementation Method 1
a pump to draw the fluid into the sample chamber until the sample chamber is substantially full
Implementation Method 2
adding a supplemental volume corresponding to the supplemental volume measurement to over-pressurize the sample chamber
Implementation Method 3
spectrometer modules, which analyze the fluids by near-infrared (NIR) absorption spectroscopy
Data Source
AI summary
Methods of and apparatus to estimate one or more volumes of one or more components of a fluid in a sample chamber of a downhole tool are described. An example method includes obtaining a sample chamber volume measurement, a flowline volume measurement and a supplemental volume measurement. The example method includes drawing the fluid into the sample chamber until the sample chamber is substantially full and measuring a characteristic of the fluid in the sample chamber at a first time to obtain a first characteristic measurement. The example method also includes adding a supplemental volume corresponding to the supplemental volume measurement to over-pressurize the sample chamber after measuring the characteristic at the first time and measuring the characteristic of the fluid in the sample chamber at a second time to obtain a second characteristic measurement. The second time is after the sample chamber is over-pressurized. In addition, the example method includes calculating a first volume of a first component of the one or more components of the fluid based on the first characteristic measurement, the second characteristic measurement, the sample chamber volume measurement, the flowline volume measurement and the supplemental volume measurement.