Reservoir wettability affects how oil, brine and injected fluids interact with rock surfaces. By measuring contact angle and interfacial tension under relevant pressure and temperature conditions, you can evaluate wettability alteration, compare EOR fluids and guide further testing.

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Understand and control reservoir wettability

Wettability plays a key role in how easily oil can be recovered from reservoir rock. Depending on the rock–fluid interactions, reservoirs can be water-wet, mixed-wet or oil-wet. In oil-wet systems, oil adheres more strongly to the rock surface, which can limit recovery and reduce the efficiency of water flooding.

Enhanced oil recovery methods often aim to shift wettability toward more water-wet conditions. Strategies such as surfactant flooding, nanofluids, CO₂ injection and low-salinity or smart-water flooding can influence wettability and interfacial tension, helping mobilize trapped oil.

Contact angle and interfacial tension measurements make these changes measurable.  By studying rock, oil, brine and EOR fluids at defined pressure, temperature and fluid compositions, you can compare formulations, understand wettability alteration and support better recovery decisions. 

Key benefits of optical tensiometers for reservoir wettability optimization

Optical tensiometers turn wettability changes into measurable data. By quantifying contact angle and interfacial tension, you can: 

Screen and rank EOR strategies

Compare how surfactants, nanofluids, CO₂ and low-salinity brines affect wettability and fluid–fluid interactions. 

Define clear wettability targets

Use contact angle ranges to quantify shifts from oil-wet toward mixed- or water-wet conditions.

Work at real reservoir conditions

Measure contact angle and interfacial tension at relevant pressure and temperature.

Support scale-up and field decisions

Shortlist promising formulations, guide core-flood tests and reduce uncertainty before field pilots. 

A typical approach to reservoir wettability studies

A reservoir wettability study typically combines contact angle and interfacial tension measurements to evaluate how rock, oil, brine and EOR fluids interact under relevant conditions. The results help compare enhanced oil recovery strategies and identify promising formulations for further testing.
  1. Set wettability and IFT targets
    Define what you want to achieve, such as shifting the rock surface from oil-wet toward mixed- or water-wet conditions or lowering oil–brine interfacial tension.
  2. Prepare rock and fluid samples
    Select representative rock or mineral surfaces, crude oil, brine and EOR fluids. Samples can be aged in crude oil to better reflect initial reservoir wettability.
  3. Measure at relevant conditions
    Perform contact angle and interfacial tension measurements at the pressure, temperature and fluid composition relevant to your reservoir or EOR method.
  4. Compare EOR strategies
    Evaluate how surfactants, nanofluids, low-salinity brines or CO₂-related systems affect wettability and fluid–fluid interactions.
  5. Guide further testing
    Use the results to shortlist promising formulations for spontaneous imbibition, core flooding or field evaluation.
case study nanoparticle EOR

Case example: Nanofluids for wettability alteration and IFT reduction

Nanoparticles are being explored as enhanced oil recovery agents because they can help alter reservoir wettability and reduce interfacial tension between oil and the flooding fluid.

In a University of Calgary study, naturally derived silicate-based nanopyroxene nanoparticles were formulated into nanofluids and evaluated using sandstone cores. With Attension Theta High Pressure, the researchers measured interfacial tension and contact angle to assess how the nanofluids performed compared with brine.

The nanofluids reduced interfacial tension, shifted the sandstone surface toward more water-wet conditions, and supported an additional 11% oil recovery after brine flooding in core flooding experiments.

Download the case study below to see how Theta High Pressure was used to evaluate nanoparticle-based EOR fluids.

Download Case Study
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Measurements

Sessile Drop

Sessile drop

For static contact angle measurement of a liquid droplet
Captive bubble

Captive bubble

For static contact angle measurement of a gas bubble
Reverse pendant drop

Reverse pendant drop

For surface and interfacial tension 
Pendant drop

Pendant drop

For surface tension
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Theta High Pressure – your solution for reservoir wettability optimization

Theta High Pressure is Biolin Scientific’s optical tensiometer for high‑pressure, high‑temperature contact angle and interfacial tension measurements. It allows you to study wettability at pressures and temperatures representative of real reservoirs. 

With Theta High Pressure you can:

  • Screen surfactants, polymers, nanoparticles and smart‑water recipes for their ability to alter wettability and reduce interfacial tension.
  • Compare CO₂‑based strategies by quantifying how dissolved CO₂ and carbonated brines affect rock–fluid interactions.
  • Generate robust datasets that help you select EOR strategies, design core-flood experiments and reduce uncertainty before field trials. 
Discover Theta High Pressure

Theta High Pressure Benefits

Quantify wettability and IFT

Replace qualitative observations with numerical contact angle and interfacial tension data that can be compared, tracked and shared across teams. 

Mimic reservoir conditions

Study how pressure and temperature affect wettability, interfacial tension and EOR fluid performance.

Reduce contamination with unique piston design

The unique piston design helps reduce contamination in the pumps and measurement chamber while keeping concentration constant during the measurement. 

Work flexibly with liquids and gases

Connect the chamber to different pumps to support both liquid- and gas-phase measurements, including CO₂-related studies.  

Work with demanding EOR fluids

Study challenging EOR systems with a high-pressure chamber built from robust materials selected for compatibility with brines, oils, surfactant solutions and CO₂-related environments. 

Expand as research needs change

Use the same Theta Flow platform for ambient measurements and add dedicated modules as your applications evolve. 
Need help selecting the right measurement setup for your EOR studies? Our experts can help you find the best approach for your samples, fluids and research goals. 
Contact our team of experts