Properties of reservoir fluids

1. Practical No. 04
Group member:- 15PG143, 15PG149, 15PG146, 15PG167, 15PG159

2. Object:
• To determine viscosity of crude/ petroleum products by Say-bolt

3. Apparatus:
• Say-bolt viscometer.
• Stop Watch
• Sample (Crude Petroleum)
• Thermometer

4. Introduction
• A device used to measure the viscosity of a fluid. The Saybolt viscometer
controls the heat of the fluid and the viscosity is the time takes the fluid to
fill 60cc container.
• The testing procedure is quite similar to capillary-tube viscometer where
efflux time of a specified volume of fluid is measured through fixed orifice
at the bottom of a cup to represent the viscosity of fluid. The efflux time in
seconds of 60 ml of sample flowing through a calibrated orifice is
measured under carefully controlled conditions.
• The time is corrected by an orifice factor and reported as the viscosity of
the sample at that temperature.

6. Explanation:
• The saybolt viscometer, one of the efflux cup viscometer is the standard
instrument for testing petroleum products. There are three types of orifices
available Universal, Furol, & Asphalt.
• The furol and asphalt orifices, respectively, have an efflux time
approximately. One-tenth and one-hundredth that of the universal orifice.
The cup orifice combination should be selected to provide an efflux time
within the range of 20 to 100 seconds. Of these types the universal orifice
(Saybolt universal viscometer) is most commonly used and its efflux time
is designated as saybolt universal seconds (SUS).

7. • The universal viscometer measures the time required for 60 cc of sample
fluid to flow out through an orifice having dimensions of 0.176 cm in
diameter and 1.225 cm in length. Saybolt universal seconds (t) can be
converted to kinematic viscosity (v) by the following equations:
• When t<100 sec, 𝑣 = 0.226𝑡−195/𝑡 Centistokes …..(1)
• When t>100 sec, 𝑣 = 0.220𝑡−135/𝑡 Centistokes ……(2)

8. Test procedure:
• 1. If the test temperature is above the room temperature the test may be
accelerated by preheating sample not more than 3 ℉ above the test
temperature.
• 2. Insert a cork stopper having a card attached for its easy removal into the
air chamber at the bottom of the viscometer. The cork shall be fit tightly
enough to prevent the escape of air as evidenced by the absence of oil on
the cork when it is withdrawn.
• 3. Filter the prepared sample through a 100-mesh screen directly into
viscometer until the level is above the overflow rim.

9. • 4. Stir sample until its temperature remains constant within 0.05℉ of the
test temperature during 1min of continuous stirring. Stir with a viscosity
thermometer equipped with thermometer support use a circular motion at
30 to 50 rpm in a horizontal plain.
• 5. Remove thermometer from the sample quickly remove the oil from the
gallery until its level is below the overflow rim. This is done by placing the
tip of with drawl tube at one point in the gallery apply suction do not touch
the over flow rim with drawl tube or the effective head the sample will be
reduced.

10. • 6. Place the receiving flask where stream of oil from the bottom the
viscometer will just strike neck of the graduated mark on the flask shall be
between 10 & 13 cm from the bottom of the viscometer.
• 7. Snap the cork from the viscometer using the attached cord. At the same
instant the time start the stop watch and stop the timer the instant the
bottom of the meniscus the graduation mark record efflux time in seconds.
• Unit
• Viscosity in SUS (Say-bolt Unit Second)

11. Advantages
• It has a digital meter to measure temperature and so reading is more
accurate and precise.
• The coils wrap around the container uniformly so uniform temperature can
be obtained.
• Viscosity can be directly compared for two or more liquids.

12. Disadvantages
• Efflux cup have some inherent inaccuracies.

13. Applications
• Saybolt viscometer is most commonly used in field work to
measure the viscosity of oil, syrups, varnish, paints.
• It is used for testing petroleum products.