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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: [email protected]
http://www.vinci-technologies.com
Interfacial Tension
Measurements With IFT 700
Measurements at reservoir conditions
http://upload.wikimedia.org/wikipedia/commons/f/f9/Wassermolek%C3%BCleInTr%C3%B6pfchen.svg
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