Interfacial Tension Measurements

VINCI TECHNOLOGIES – http://www.vinci-technologies.com Page 1

What is IFT and why do I need it?

The physical phenomenon between gas and oil or between water and oil called

surface or interface tension (IFT) results from the attractions due

to intermolecular forces. In bulk fluid, each molecule is

surrounded by equivalent neighbor molecules, so the

balance of intermolecular force is zero.

A molecule at the interface of two fluids (gas and liquid or

two non-miscible liquid) is surrounded with two different

neighboring medium and it results an inward force. These

molecules are subject to molecular attraction balanced by the fluid’s resistance to

compression.

The surface acts like a stretched elastic membrane. Therefore, to minimize its

energy state, the number of boundary molecules is minimized. In other words, the

fluid is squeezed to reach the lowest local surface possible. For a fluid-solid system,

a similar phenomenon called wettability occurs due to adhesive and cohesive force.

Wetting and surface force are responsible for capillary effects.

In reservoir engineering, oil, water and gas can coexist in a porous media (reservoir

rock) and the interfacial forces act in the equilibrium of this system. Therefore, the

IFT data and wettability are required to

describe the complete system. In other words,

wettability determination is critical for the

reservoir, because it influences the

distribution of gas, oil and water within the

reservoir rock, capillary pressure and relative

permeability characteristics.

It explains why there are so many

applications from IFT data in oil & gas

production, chemical and petrochemical

processing and others.

VINCI TECHNOLOGIES Parc de l'Ile, 27B rue du

Port, 92022 NANTERRE Phone: 331 41 37 92 20

e-mail: vincinet@vinci-technologies.com-

http://www.vinci-technologies.com

Interfacial Tension

Measurements With IFT 700

Measurements at reservoir conditions

Interfacial Tension Measurements

VINCI TECHNOLOGIES – http://www.vinci-technologies.com Page 2

For example, knowing and controlling the in situ IFT, gas injection, use of agents such as

brines, surfactants, miscible and immiscible solvents, EOR schemes can be designed more

efficiently.

To recreate this scenario, inside of IFT meter a liquid drop is created and put in contact

with gas or solid in a cell at reservoir conditions to be possible wettability and Interfacial

tension measurements.

Vinci Technologies puts at your disposal the IFT meter which allows determination at

reservoir conditions of interfacial tension between liquid-gas and liquid-liquid interfaces

using pendent drop method as well as the sessile method (contact angle between liquid

and solid interfaces). Besides, complementary Drop Analysis System home-made software

is provided.

IFT Measurements

The apparatus allows for the determination at reservoir conditions of: Surface Tension (liquid-gas) and Interfacial tension (liquid-

liquid) using the pendant drop method (Laplace equation) Contact angle between liquid-gas or liquid-liquid and solid

system using the sessile drop method

For both measurement, the geometry of a drop is analyzed optically. The IFT 700 brings to you the opportunity to analyze experiences at high pressure (up to

69 MPa or 10000Psi) and high temperature (up to 180°C).

Pendant drop method

A drop is generated from the end of a capillary needle in a bulk fluid at reservoir

conditions (Pressure and Temperature). With a calibrated and accurate video lens

system, the complete shape of the drop is analysed with an advancedDrop Shape

Analysis software.

Then, the Laplace equation (non linear system of differential equation) is solved

numerically over the complete shape (accuracy better than the usual method of the

two diameter De, Ds with drop shape factor from tables) to get the IFT.

Sessile drop method

A way to study liquid-solid interaction

resides in leaving a liquid-droplet on a

cleaned and polished area of a solid

(example : drop of oil inside brine).

Then, the contact angle (left and right) is

measured optically with the video system.

This method is used to measure the static contact angle for wettability

determination of solids.

IFT features

Interfacial Tension Measurements

VINCI TECHNOLOGIES – http://www.vinci-technologies.com Page 3

The IFT system includes a high pressure viewing cell with

capillary injector to generate the drop at reservoir

conditions. It is equipped with sapphire windows in both

ends for complete visibility.

It enables various drop configurations for IFT and contact

angle measurement:

Pendant drop: for example, a drop of oil inside gas as bulk phase

Rising drop: for example, a drop of oil inside brine as bulk phase

A support for core sample is also available for sessile drop experiment.

Two manual pumps are connected to cell: the first one for the drop and the second for the

bulk phase.

A telecentric optical system with video camera is added to capture the shape of the drop.

The camera is connected to a computer and records all process of drop formation. With a

drop suspended in bulk fluid from the end of the capillary injector, while keeping a

constant pressure and temperature, the image of the drop profile is captured

automatically.

At the same time, the images are processed by home-made software and the value of IFT

and related parameters are displayed.

Summary of Pendant drop method recorded by DAS

It must be stressed that the Drop Analysis System software allows the fast

calculation of surface and interfacial tension of pendant drop and contact angles

of sessile drops (up to 15 calculations per second).

A control panel displays in real time the pressure and temperature of the system.

Drop Analysis Software (DAS)

Vinci Technologies has developed a robust software dedicated to Oil & Gas

laboratories, to measure and calculate quantities of interest from the drop shape

including:

- Left/right contact angle

- Pendant or Rising drop surface/Interfacial

tension

- Drop volume, diameter

All measures are, according with pressure and

temperature.

Once the drop is formed the DAS (Drop Analysis

System), user just needs to enter the density of the

two fluids, select the nature of experiment (Pendant,

Rising, Sessile … drop), then click on “Run

measurements” and it provides immediately

accurate results.

DAS is very easy to use and the operator can execute automated measurements. The

software can save periodically all the parameters with the image associated. Movies from

experiment can be also processed.

All the functions can be easily achieved and controlled from a user-friendly interface.

Interfacial Tension Measurements

VINCI TECHNOLOGIES – http://www.vinci-technologies.com Page 4

Example 1: Rising Drop Experiment

The Rising Drop Experiment from DAS

Example 2: IFT Results

Variation of Interfacial Tension of gas – oil with Pressure

Applications:

Interfacial Tension Measurements

VINCI TECHNOLOGIES – http://www.vinci-technologies.com Page 5

Determination at reservoir conditions of:

Interfacial tension between liquid-gas and liquid-liquid

interfaces using pendant drop method

Contact angle between liquid and solid interfaces using

sessile drop method

Benefits:

Reservoir conditions: 10000Psi – 180°C

Accurate results with custom optical system associated to

advanced algorithm

Easy to use, dedicated to Oil & Gas laboratories

Very good stability of the drop

Low maintenance cost

Technical Specifications

Item Type / model /

specification

IFT standard measurements: 0.1 to 72 mN/m

Cell volume: 25 cc (Bulk fluid)

Operating pressure: 700 Bar – 10 000 Psi

Operating Temperature: ambient to 180 °C

Wetted parts: Stainless steel, PTFE, Viton

Pump: Two hand pumps of 20cc

Connections: 1/8” LP Autoclave or Butech type (15 000Psi)

Power requirement: 240 VAC 50/60Hz single phase plus ground

power – 1 kW