HPOC and IRHPOC

High-Pressure Optical Cell (HPOC)

1. Overview

The High-Pressure Optical Cell (HPOC) is a precision laboratory device designed for in-situ visual observation of fluid behavior under reservoir-representative pressure and temperature conditions.
It allows direct study of phase transitions, gas–liquid interactions, miscibility development, and solid precipitation (asphaltene, wax, hydrate) in oil–gas–water–CO₂ systems.
The HPOC serves as the core platform for microscopic visualization, infrared imaging, and Raman spectroscopy in CO₂-EOR and CCUS research, bridging the gap between macroscopic PVT measurements and microscopic interfacial phenomena.

2. Principle

The HPOC operates by enclosing a small fluid volume within a transparent, high-strength optical chamber made of sapphire, quartz, or fused silica, capable of withstanding pressures up to 150 MPa and temperatures up to 200 °C.
One or both sides of the cell are equipped with optical windows aligned with a microscope or spectrometer, allowing real-time visualization and spectral monitoring.

Under controlled P–T conditions, the system enables researchers to observe:

  • CO₂ dissolution and phase mixing with crude oil;

  • Bubble-point and dew-point phenomena;

  • Asphaltene/wax precipitation and flocculation;

  • Emulsion and interfacial film formation;

  • Mineral dissolution and CO₂-water reactions.

3. System Configuration

A typical HPOC system comprises:

  • Pressure chamber (cell body):
    Machined from high-strength stainless steel, Inconel, or titanium alloy. The inner chamber (0.1–5 mL) houses the sample under controlled P–T conditions.

  • Optical windows:
    High-clarity sapphire or fused-silica disks sealed with metal gaskets to provide full optical access for visible, infrared, and Raman wavelengths.

  • Temperature-control system:
    Electrical heating jacket, Peltier, or Linkam-style thermal stage maintaining uniform sample temperature (accuracy ± 0.1 °C).

  • Pressure control:
    Precision syringe or piston pump maintaining target pressure (± 0.01 MPa) and enabling fluid injection or withdrawal.

  • Optical interface:
    Coupled to a microscope, Raman microprobe, or IR imaging system via objective lenses or fiber-optic ports.

  • Data acquisition and imaging:
    High-resolution CCD/CMOS camera and software for recording real-time phase behavior, interface motion, and solid formation.

4. Experimental Applications

  1. CO₂–Oil Interaction Studies:
    Visualization of bubble formation, droplet shrinkage, and miscibility development during CO₂ injection.

  2. Asphaltene/Wax Precipitation Analysis:
    Observation of particle nucleation, aggregation, and re-dissolution under controlled pressure depletion or temperature variation.

  3. Phase Behavior Determination:
    Identification of bubble-point, dew-point, and asphaltene onset pressure (AOP) in live oil systems.

  4. Surfactant and Additive Evaluation:
    Monitoring interfacial tension reduction and film stabilization effects of amphiphilic chemicals or nanoparticles.

  5. CO₂–Water–Rock Reaction:
    Studying mineral dissolution and carbonate scaling relevant to CCUS storage integrity.

  6. Flow Assurance Research:
    Real-time tracking of hydrate or solid deposition under simulated pipeline conditions.

5. Data and Output

The HPOC provides:

  • Visual phase behavior images (gas, liquid, solid phases);

  • Quantitative measurements of interface movement, droplet size, and growth kinetics;

  • Spectral data (Raman/IR) for compositional change analysis;

  • Pressure–temperature–composition (P–T–x) relationships for PVT and EOR modeling.

Combined with slim-tube and core-flood data, these results enhance understanding of CO₂ miscibility mechanisms and solid deposition dynamics in reservoir fluids.

6. Advantages

  • True in-situ observation under high P–T conditions;

  • Non-destructive, real-time monitoring of multiphase systems;

  • Multi-modal capability: optical, infrared, and Raman compatible;

  • Compact and modular design for integration with pumps, spectrometers, or thermal stages;

  • High precision and repeatability, suitable for fundamental and applied research.

7. Summary

The High-Pressure Optical Cell (HPOC) is a vital experimental tool for modern reservoir fluid and CO₂-EOR studies, enabling visualization of microscopic processes that govern macroscopic flow and phase behavior.
Its ability to replicate reservoir P–T conditions and to couple with advanced optical and spectroscopic systems makes it indispensable for investigating CO₂ miscibility, asphaltene/wax precipitation, and fluid–rock–CO₂ interactions.

Through HPOC-based experiments, researchers can obtain direct mechanistic insights essential for designing chemical EOR strategies, predicting flow assurance risks, and ensuring CCUS storage integrity.

Infrared High-Pressure Optical Cell (IRHPOC)

1. Overview

The Infrared High-Pressure Optical Cell (IRHPOC) is an advanced laboratory apparatus designed for in-situ infrared imaging and microscopic visualization of multiphase fluid systems under reservoir-representative temperature and pressure conditions.
It integrates the optical accessibility of a high-pressure optical cell (HPOC) with the spectroscopic capability of infrared (IR) transmission or imaging, enabling simultaneous observation of phase transitions, molecular interactions, and solid precipitation within oil–gas–CO₂–water systems.

The IRHPOC technique provides direct visual and spectroscopic evidence of key thermodynamic and transport phenomena—such as CO₂ dissolution, miscibility development, asphaltene/wax onset, hydrate formation, and interfacial film evolution—under true reservoir conditions.

2. Principle

The IRHPOC operates on the principle of infrared light transmission through transparent optical windows under high pressure.
When IR radiation passes through the confined sample, variations in absorbance spectra and spatial intensity reflect compositional and structural changes in the fluid phases.
This allows researchers to correlate molecular-level interactions (IR spectra) with macroscopic phase behavior (visual images) in real time.

The system maintains pressure up to 150 MPa and temperature up to 200 °C, reproducing conditions found in deep reservoirs or supercritical CO₂ processes.
All measurements are conducted in-situ, without depressurization, ensuring that phase evolution and precipitation are observed under true thermodynamic equilibrium.

3. System Configuration

A typical IRHPOC system includes the following components:

  • High-pressure optical chamber:
    Machined from stainless steel or Inconel, with optical windows made of IR-transparent sapphire, ZnSe, or CaF₂, allowing full transmission from visible to mid-infrared wavelengths.
    Internal volume ranges from 0.3 mL to 5 mL.

  • Infrared imaging and optical path:
    Coupled to an FT-IR microscope, IR camera, or imaging spectrometer, capable of capturing 2D IR intensity maps or spectral cubes (absorbance vs. wavelength and position).

  • Pressure and temperature control system:
    High-precision syringe or piston pumps regulate internal pressure (accuracy ±0.01 MPa), while an electrical or Linkam-style thermal stage provides temperature stability (±0.1 °C).

  • Injection and sampling ports:
    Allow controlled introduction of CO₂, crude oil, brine, or chemical additives for dynamic displacement or mixing tests.

  • Data acquisition system:
    Synchronizes infrared spectral data, optical video recording, and pressure–temperature readings for comprehensive analysis.

4. Experimental Applications

  1. CO₂–Oil Miscibility Visualization:
    Monitoring CO₂ dissolution, droplet shrinkage, and interface disappearance as miscibility develops; correlating IR absorption changes with phase composition.

  2. Asphaltene and Wax Precipitation:
    Detecting onset and growth of solid phases via both visible imaging and IR spectral signatures (aromatic C=C, aliphatic C–H stretching).

  3. Chemical Additive Evaluation:
    Studying surfactant or nanoparticle effects on interfacial tension, film stability, and CO₂ solubility enhancement.

  4. CO₂–Brine–Mineral Interaction:
    Observing carbonate dissolution, ion exchange, and mineral carbonation reactions during CCUS experiments.

  5. Phase-equilibrium and Thermodynamic Analysis:
    Determining bubble-point, dew-point, and Asphaltene Onset Pressure (AOP) with simultaneous spectral and optical confirmation.

5. Data and Interpretation

The IRHPOC provides quantitative and qualitative datasets, including:

  • Infrared spectra (4000–650 cm⁻¹): identifying molecular vibrations and phase-specific bands;

  • Infrared intensity maps: visualizing spatial heterogeneity and phase boundaries;

  • High-resolution optical images: tracking morphological changes of bubbles, droplets, and solids;

  • Pressure–temperature–spectra correlation plots: linking thermodynamic parameters to compositional evolution.

By combining IR spectral data with microscopic imaging, researchers can directly relate molecular absorption features to macroscopic phase transformations—a unique advantage over conventional PVT or bulk spectroscopic methods.

6. Advantages

  • Simultaneous optical and infrared observation of fluids under true reservoir P–T conditions.

  • Non-destructive, real-time monitoring of compositional and phase changes.

  • Quantitative molecular identification through IR spectral analysis.

  • High-precision control of pressure, temperature, and injection sequence.

  • Compatibility with Raman or UV–Vis modules for multimodal spectroscopy.

  • Compact, modular design suitable for integration with EOR/CCUS laboratory systems.

7. Summary

The Infrared High-Pressure Optical Cell (IRHPOC) represents a powerful experimental platform for studying multiphase flow, CO₂–crude oil interactions, and solid deposition mechanisms under reservoir-relevant conditions.
It bridges molecular-scale spectroscopy and macroscopic visualization, enabling direct observation of chemical, physical, and interfacial phenomena crucial to CO₂-EOR, CCUS, and flow-assurance research.

By combining infrared imaging, optical microscopy, and precise P–T control, IRHPOC provides a unique window into the dynamic behavior of complex fluids—advancing both fundamental understanding and practical design of CO₂ utilization and storage technologies.