Asphaltene Onset Pressure Detection via Light Transmission
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Solution Overview
Problem
Current methods for determining asphaltene onset pressure in wellbore environments are inadequate due to the need for large fluid samples, extensive mixing equipment, slow depressurization rates, and intense light sources, which are not suitable for field applications and often confuse asphaltene onset pressure with bubble point pressure.
Innovation Solution
A method and system that use a light source to transmit light through a small sample of formation fluid, decrease pressure, detect intensity changes, and determine asphaltene onset pressure by analyzing wavelength-dependent signals, distinguishing it from bubble point pressure using a controller and pressure control unit, allowing for efficient measurement in a wellbore setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large formation fluid sample (10 mL-100 mL) is used for light transmission measurement, then measurement accuracy is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The measurement system is segmented into a small-volume flow line (micro-scale) rather than requiring large bulk samples. The flow line contains only a small portion of the formation fluid at a time, enabling the system to achieve accurate measurements without handling large volumes of fluid, thus reducing device complexity and ease of operation requirements.
2Measurement precision
If slow depressurization rate (100 psi/hour) is used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system dynamically adjusts the depressurization rate based on real-time light transmission signal monitoring. By using a microprocessor to control the depressurization process and detect asphaltene onset through optical signals, the system can optimize the depressurization speed to achieve accurate measurements faster than conventional slow depressurization methods, reducing time loss while maintaining precision.
3Measurement precision
If intense light source (laser) is used for light transmission measurement, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system changes the parameters of the light source and detection system to optimize for small-volume measurements. By using a flow line with small cross-sectional area and adjusting the light path length and intensity parameters, the system achieves sufficient measurement precision without requiring intense laser sources, thereby reducing energy consumption while maintaining detection accuracy.
4Measurement precision
If additional mixing equipment is used, then measurement precision is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The system uses the natural flow dynamics and pressure differential within the flow line to maintain equilibrium in the formation fluid sample without requiring external mixing equipment. The fluid flow itself provides the necessary mixing action, allowing the system to maintain measurement precision while simplifying operation and reducing device complexity.
5Measurement precision
If large enclosed volume is used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system segments the fluid sample into a small volume within the flow line, allowing rapid depressurization and equilibration. By working with a small enclosed volume rather than a large one, the system achieves accurate asphaltene flocculation detection while significantly reducing the time required for depressurization and measurement, thus eliminating the time loss associated with large-volume measurements.
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
Enables accurate and efficient determination of asphaltene onset pressure using smaller sample volumes and shorter time scales, effectively distinguishing it from bubble point pressure, thereby improving well production and reducing production curtailment.
Implementation Method 1
transmitting light through a sample of the formation fluid
Implementation Method 2
bubbles scatter light, which reduces light transmission
Implementation Method 3
decreasing pressure of the sample
Implementation Method 4
the asphaltenes will begin to flocculate
Implementation Method 5
detecting intensity of the transmitted light during depressurization
Data Source
AI summary
Methods and systems for determining for determining asphaltene onset pressure of a formation fluid are described herein. The method includes the following processes: (a) transmitting light through a sample of the formation fluid; (b) decreasing pressure of the sample; (c) detecting intensity of the transmitted light during depressurization; (d) identifying a change in intensity of the transmitted light during depressurization; (e) increasing pressure of the sample to a fixed pressure; and (f) detecting intensity of the transmitted light at the fixed pressure and at an equilibrated light intensity. Processes (a) to (f) are repeated for a number of different fixed pressures. The asphaltene onset pressure of the formation fluid sample can be determined using (i) the intensity of the transmitted light during each depressurization and (ii) the intensity of the transmitted light at each of the different fixed pressures.