The Attension® Theta High Pressure is a tensiometer for measuring wettability and interfacial tension at high pressures and high temperatures within enhanced oil recovery research. With the harsh conditions of an oil reservoir in mind, the instrument is designed to ensure ease of use and yet offer wide measurement possibilities.


Features & Benefits

Easy to Use

  • Sample introduction and system cleaning made simple
    The smart sample port enables direct introduction of sample with a syringe and direct cleaning of the same sample line without passing through a pump.
  • Minimal corrosion risk
    There is no need to add corrosive liquids through the pump as the pressure can be increased by a piston inside the chamber. The corrosive liquid is placed directly in the corrosion-resistant chamber to minimize any corrosion risk. 
  • Automated pressure control
    When using an optional automatic pump, the measurement pressure can be automatically reached. Changing the pressure is always just a click away.

Facilitates Measurements

  • Automatic droplet creation
    With automatic pumps, droplet creation can be automated to reduce hands-on time.
  • Surfactant studies at constant concentration
    Thanks to the piston, pressure can be increased without changing surfactant concentration, unlike in conventional designs.
  • Intuitive software with high functionality
    OneAttension software features include live analysis and automatic measurements. Drop volume is shown regardless of the pump being used.

Offers Broader Surface Science Possibilities

  • Liquid and gas studies
    The optional automatic syringe pump easily compresses either gas or liquid compared to traditional pumps mainly for liquids.
  • Wide experimental conditions
    Temperature control options for both elevated temperatures and sub-room temperatures.
  • Versatility in Measurements
    Surface tension, interfacial tension, contact angle and surface free energy in one set. The possible sample size for contact angle measurements is the biggest on the market.


Applications mainly relate to enhanced oil recovery and supercritical fluids. By measuring wettability and interfacial tension with Attension Theta High Pressure you can get information on how to optimize:

  • EOR processes by measuring interfacial tension between oil, brine, water, surfactant solution, CO2 or other EOR fluids
  • Rock material wettability to increase oil reservoir yield
  • Efficiency of CO2 in flooding EOR by measuring the minimum miscibility pressure (MMP) of CO2
  • CO2 storage and wettability of rock material with CO2
  • EOR oil displacement with supercritical fluids (SCF)
  • Drilling fluid composition and effectiveness

Product details and specifications

The Attension Theta High Pressure is an optical tensiometer with a high pressure chamber inside which the measurement takes place. 

The instrument consists of high-quality parts that ensure the ease of use, functionality and safety of the system. The chamber itself is made from corrosion resistant stainless steel and can be optionally offered to be made from Hastelloy instead. The chamber includes three windows for visualizing the interphase. The chamber can be placed either in upright or inverted position which removes the need for using hooked needles as the same straight needle can be used independent of the phases. The chamber sits on the Attension Theta optical tensiometer which uses Full HD-resolution camera to image the interphase precisely.

The unique piston enabling accurate and convenient surfactant and brine studies is placed inside the measurement chamber. Next to the chamber, a sample port is situated which is used for introducing the sample and for flushing the sample line easily. All other valves are integrated to a valve door to be able to safely and conveniently open and close the desired pressure lines. The valve door is a part of the larger safety cabinet that makes the system exceptionally safe to use.

For temperature control of the chamber there are two options: resistor heating or Peltier heating and cooling. Resistor heating enables software-controlled temperature range from ambient to 200 degrees Centigrade whereas the Peltier element combined to a water bath enables temperature control from 1 to 70 degrees Centigrade.

The system uses two high pressure pumps: one to create pressure in the chamber and one to create the droplet under high pressure. Thanks to the flexible design of the Attension Theta High Pressure, the system can be used with both automatic and manual pumps and can even be connected to pre-existing pumps if preferred. The manual pump is an economic solution for performing measurements using liquids. An automated HPLC pump automates the liquid droplet creation and/or liquid pressure increase in bulk. For gasses, their compression capability is limited and an automated syringe pump is required. Using a configuration of one manual and one automatic pump enables gas measurements conveniently.

If required, the entire chamber can be disassembled and reassembled easily within minutes. This makes cleaning of the chamber convenient as the parts can be flushed or washed in a washing machine.

The Attension Theta High Pressure keeps its user well protected with multiple safety mechanisms. Two overpressure valves automatically release any excess pressure through the release lines. Overheating is prevented using both an overheating switch that will cut the heating power if the temperature exceeds the maximum temperature limit as well as with the OneAttension software that will refuse to overheat the chamber. The cabinet with its easily-accessible valves reduces the need to be near the heated and pressurized parts.

Technical specifications

Manual measurements of liquids
Automated measurements of liquids
Automated measurements of liquids and gases

Included high pressure pumps

2 manual pumps 2 automated HPLC pumps 1 automated syringe pump
1 automated HPLC pump

Temperature range

ambient...200C ambient...200C 1...200C

Measurement types

Surface tension, interfacial tension, contact angle, surface free energy  

Maximum pressure

400 bar  

Chamber volume

85ml (without piston), 40-62ml (with piston)  

Pressure control options

Pressure increase by piston or by adding more liquid/gas with pump  

Sample introduction and flushing

Through integrated 6-port valve  

Max solid sample size

20 mm x 20 mm x 8 mm (xyz)  

Maximum camera resolution

1984 x 1264 px  

Maximum measuring speed

3009 fps  

All-inclusive software



74 cm x 25 cm x 61 cm (L x W x H) for Theta and chamber  


35 kg (Theta and chamber)  

Power supply

100 - 240 V AC  


50 - 60 Hz  

Recommended system requirements

2 GHz processor, 2 GB RAM, 120 GB hard disk drive1, 1024x768 resolution, 1 USB2 or USB3 port, 1 USB3 port, 1 additional USB2 or USB3 port if Peltier used, Windows7/8/10 (32 or 64 bit)  

Application example

Wettability of CO2 in Enhanced Oil Recovery (EOR)

In order to gain the maximum yield from an oil reservoir, methods grouped under the name enhanced oil recovery (EOR) are used. One common EOR method is to use CO2 to both dissolve and displace oil in a reservoir.

To study the effectiveness of the CO2, the wettability of it can be measured by using interfacial tension and contact angle measurements. The interfacial tension between CO2 and brine, for example, correlates with how easily carbon dioxide can be pumped into the reservoir. Likewise, the contact angle of an oil drop in a carbon dioxide environment gives a measure how well the CO2 can displace the oil on rock surface.

For more detailed information about using CO2 in enhanced oil recovery, see:

CO2 in Enhanced Oil Recovery

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