Fluid Composition Analysis Using Standard Addition Calibration
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Solution Overview
Problem
Off-line laboratory analyses of fluids from subterranean hydrocarbon-bearing formations often provide inaccurate results due to changes in fluid characteristics during sampling and detection limitations for low-concentration analytes, leading to inaccurate chemical composition determination.
Innovation Solution
The use of standard addition methods in a measurement system that circulates sample fluids under varying conditions, incorporating a standard fluid to improve detection limits and minimize flash effect errors, allowing for real-time calibration and accurate analysis of fluid properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If off-line laboratory analyses are used to determine fluid composition, then detailed chemical analysis can be performed, but the analysis accuracy deteriorates due to changes in fluid characteristics during sampling and lag time
Solution Approach 1:
The patent applies preliminary action by performing calibration and analysis procedures before the fluid composition changes occur. The system pre-establishes calibration curves using standard fluids and prepares measurement parameters in advance, so that when field samples are analyzed, the measurements can be immediately compared against pre-established reference data, eliminating the need for time-consuming post-sampling laboratory procedures
Solution Approach 2:
The patent replaces mechanical/physical transportation of samples to laboratories with an optical/electronic measurement system deployed in the field. Instead of physically moving fluid samples through time and space to laboratory equipment, the system uses optical sensors and electronic signal processing to perform composition analysis in-situ, substituting the mechanical sampling and transportation process with a stationary measurement apparatus that captures data before fluid characteristics change
2Measurement precision
If standard measurement systems are used to detect analytes, then the system remains simple and reliable, but the detection capability deteriorates for low concentration analytes below detection limits
Solution Approach 1:
The patent applies parameter changes by introducing standard fluids with known concentrations into the measurement system to create calibration curves. By systematically varying the concentration parameter of standard analytes and measuring the corresponding sensor responses, the system establishes a mathematical relationship that enables detection of low concentration analytes through extrapolation, effectively lowering the detection limit without requiring more sensitive hardware
Solution Approach 2:
The patent uses standard fluids as intermediaries between the measurement system and unknown field samples. These standard fluids with known concentrations serve as a reference medium that bridges the gap between the sensor's native detection capabilities and the need to measure trace analytes in field samples, allowing the system to detect low concentrations through comparison rather than direct detection
3Productivity
If real-time field analysis is implemented, then the analysis speed improves and lag time is reduced, but the measurement accuracy may deteriorate due to flash effect errors and environmental conditions
Solution Approach 1:
The patent implements feedback by continuously monitoring sensor responses to standard fluid injections and using this information to dynamically adjust calibration parameters. The system measures the actual sensor response to known standard concentrations, compares it against expected values, and uses this feedback to correct for environmental variations and flash effect errors, maintaining measurement accuracy in real-time field conditions
Solution Approach 2:
The patent applies preliminary action by performing calibration injections of standard fluids immediately before analyzing field samples. This preliminary measurement establishes the current sensor response characteristics under the specific environmental conditions present at the time of analysis, allowing the system to compensate for temperature, pressure, and other environmental variations that would otherwise degrade measurement accuracy
Data Source
AI summary
A disclosed measurement system includes a fluid system that circulates a sample fluid exhibiting one or more unknown characteristics and being configured to receive a standard fluid that exhibits a known characteristic corresponding to at least one of the one or more unknown characteristics, an isolation cell fluidly coupled to the fluid system such that the sample fluid and a mixture of the sample fluid and the standard fluid are able to enter the isolation cell, an analyte-sensitive measurement device having one or more sensors associated therewith and being configured to analyze the sample fluid and the mixture and generate response signals corresponding to the one or more unknown characteristics of the sample fluid, and a signal processor configured to receive and perform standard addition calculations on the response signals in order to determine a concentration of the one or more unknown characteristics.