finding mud viscosity with marsh funnel

1. 1
Petroleum department
3rd stage
Group (A)
Drilling Lab
3rd
Experiment:
Marsh Funnel Viscosity
Date of experiment: December 10th
2015
Supervised by:
Mr. Pshtiwan Jaf
Prepared by:
Muhammad Faisal

2. 2
Aim of experiment:
The aim of this experiment is to determine the change in the
viscosity of drilling fluid.

3. 3
Theory:
Viscosity is the internal resistance of a fluid to flow. This
phenomenon is attributed to the attraction between molecules of a
liquid and is a measure of the combined effects of adhesion and
cohesion on suspended particles and the liquid environment. The
greater this resistance is, the higher will be the viscosity. In other
words, it is the resistance offered by a liquid to the forces trying to
make it flow.
The most familiar device for the checking of viscosity is the
Marsh funnel, which measures viscosity qualitatively in seconds per
quart. To determine Marsh funnel viscosity, the funnel is filled to the
bottom of the screen. The funnel holds 1,500 cubic centimeters (cc).
The time in seconds required for a quart (946 cc) to flow out the
bottom of the funnel is recorded as the Marsh funnel viscosity. The
funnel must be calibrated so that the viscosity of water is 26 ± 0.5
s/quart at 65-75°F. It should be kept in mind that the funnel
viscosity is only a relative value and cannot be used for correlations
or calculations of flow regimes. Its primary function is to monitor
the viscosity trend. A definite recorded continuous increase or
decrease in funnel viscosity means that there are mud problems
and should be checked with an instrument such as the rotational
viscometer to determine the exact problem and its cause. (Azar &
Robello, 2007)

4. 4
Introduction:
The marsh funnel is made of break-resistant plastic and has a
fixed orifice with a specified diameter. A fixed mesh near the top
across half the cone avoids the orifice getting blocked by greater
particles. The high-impact plastic measuring cup is designed
specifically for use with marsh funnel viscometer and has scales in
cubic centimeter and fluid ounces.
The marsh funnel viscosity respectively the funnel flow time is
the ratio of the speed of the sample fluid as it passes through the
orifice to the amount of force that is causing the fluid to flow. The
marsh funnel viscosity is reported as the number of seconds
required for 946 cm³ of sample fluid to flow out of a full marsh
funnel.

5. 5
Apparatus & materials:
Mud balance Electronic balance Beaker
Syringe Electric mixer & steel vessels
Water

6. 6
Marsh Funnel & quart Stop Watch
Calibration:
1. Clean the funnel and the quart.
2. Put the funnel in a balanced vertical position with the quart
right under it.
3. Bring some fresh water at around 70℉.
4. Block the outlet of the funnel with a finger.
5. Fill the funnel with the fresh water till it reaches a certain point
indicated with a line inside the funnel.
6. Quickly move your finger from the outlet to allow the water to
flow from the outlet to the quart below and start the stop
watch.
7. Let the water come down from the funnel to the quart till the
water level reaches 946cc which is indicated by a line inside the
quart.
8. When the water reaches the required level close the outlet of
the funnel with a finger again and stop the stop watch.
9. For the calibration to be correct the time required for the water
to fill 946cc of the quart should be 26 ± 0.5𝑠.

7. 7
Procedures:
1. Prepare 1000cc of a mud with 8.6ppg.
2. Hold the clean, dry funnel in an upright position with a finger
over the outlet, and then pour the freshly obtained sample of
mud to be tested through the mesh until the fluid level reaches
the bottom of the mesh (approx. 1500 cm³).
3. Quickly remove the finger from the outlet. Measure the time it
takes the fluid to fill to the 946 cm³ mark of the cup.
4. Report the temperature of the fluid and the time to the
nearest second as marsh funnel viscosity.

8. 8
Discussion:
Q1) what are the applications of Marsh funnel?
Q2) Marsh Funnel readings are qualitative measurements. Frequent
reporting of Marsh Funnel viscosity will show changes in fluid
viscosity that could require corrective action. Mud engineers
depend on the Marsh Funnel to check the quality of drilling mud.
Q2) why is Marsh Funnel the most common way to determine
viscosity? And why is viscosity so important in drilling?
A2) Marsh funnel is the quickest way to find viscosity and the
alternation happened in the muds viscosity during the circulation.
The viscosity is very important because it has direct effects on
circulation speed drill pipe rotation and rate of penetration.
Q3) what is the mesh in the funnel used for?
A3) it is used for preventing large particles to enter the orifice of the
funnel and close the outlet.
Q4) what are the advantages of Marsh funnel over the other
viscosity instruments?
A4)
 Quick, on-the-spot measurements for periodically reporting
mud consistency.
 Simple, low-maintenance.
 Transports easily for use in the lab, field, or on drilling rig.
 Rugged, break-resistant plastic that holds shape with
temperature changes.
Q5) what are the limitations of Marsh funnel?
A5) Marsh funnel only indicates whether there is a change in the
muds viscosity or not. It doesn’t measure the viscosity because
viscosity is measured in Poise not in seconds.

9. 9
References:
Azar, J. J. & Robello, S. G., 2007. Drilling Engineering. Tulsa,
Oklaoma: PennWell Corporation.
Hughes, T., LaMoreaux, J. J. & Assaad, F. A., 2013. Field Methods
for Geologists and Hydrogeologists. NewYork: Springer Science &
Business Media.
Lorenz, M., Plisga, G. J. & Lyons, W., 2016. Standard Handbook
of Petroleum and Natural Gas Engineering. 3rd ed. s.l.:Gulf
Professional Publishing.