This document describes an experiment to measure the viscosity of drilling mud using a Marsh funnel. It provides background on viscosity and how it is an important property of drilling fluids. The marsh funnel procedure involves pouring mud through a screen into the funnel and timing how long it takes for 1 quart to drain out. The measured time is used in a formula along with mud density to calculate viscosity in centipoise. Precautions for the experiment and sample questions for a viva voce discussion are also outlined.

1. Drilling Engineering-I
Pet-E-211L
Lab Instructor :
Engr. Muhammad Awais Qureshi
Department of Petroleum &
Gas Engineering 5/5/2021

2. Experiment # 03
• Objective:
1) Measurement of the viscosity of drilling mud using
marsh funnel.
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3. Apparatus
• Marsh Funnel
• Graduated Beaker
• Drilling Mud Balance
• PPE’s (Personal Protective Equipments)
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4. Related Theory
• Viscosity:
• A property of fluid and slurries that indicates their resistance to flow, defined
as the ratio of shear Stress to shear rate.
• Units:
1) Poise is the unit for viscosity (dyne-sec/cm2)
2) One poise represents a high viscosity, 1/100poise, or one centipoise (cp)
units are used for mud viscosity measurements.
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5. Marsh Funnel
• A conical-shaped funnel, fitted with a small-bore
tube on the bottom end through which mud flows
under a gravity head.
• A screen over the top removes large particles that
might plug the tube giving wrong result.
• In the test standardized by API for evaluating
water-base and oil-base muds, the funnel viscosity
measurement is the time (in seconds) required for
one quart of mud to flow out of a Marsh funnel into
a graduated mud cup.
• Funnel viscosity is reported in seconds (for one
quart)
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6. • Quart:
• The quart is a unit of Volume.
• 1 Quart (US Liquid) = 946.352 ml or cc
• Calibration:
• Water is generally used to calibrate marsh funnel.
• Water exits the funnel in about 26 seconds.
• Find out the positive or negative error, if present.
• The effective viscosity is determined from following simple formula.
• 𝜇 = 𝜌 𝑡 − 25
Where ,
𝜇 = effective viscosity in centipoise (cp)
𝜌 = 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑖𝑛
𝑔
𝑐𝑚3
t= quart funnel time in seconds
• This test was one of the earliest mud measurements for field use.
• Simple, quick and fool-proof, it still serves as a useful indicator of
change in the mud by comparing mud-in and mud-out sample funnel
viscosities.
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7. Marsh Funnel
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8. Measurement Procedure
1) When the funnel is an upright position, cover the orifice with
a finger and rapidly pour a freshly collected mud sample
through the screen into the funnel until the mud just touch
the base of the screen.
2) Immediately remove the finger from the orifice and measure
the time required for the mud to fill the viscosity cup to one
quart level in the beaker.
3) Remove the error if present, then report the result to the
nearest second as the march funnel provide viscosity in
seconds, at the temperature or measurement in degree
Celsius.
4) Using the formula, we can convert one quart funnel time into
centipoise (cp).
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9. Demonstration
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10. Observation and
Calculations
• The effective viscosity is determined from following simple formula.
• 𝜇 = 𝜌 𝑡 − 25
Where ,
𝜇 = effective viscosity in centipoise (cp)
𝜌 = 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑖𝑛
𝑔
𝑐𝑚3
t= quart funnel time in seconds
• Density of mud calculated by using mud balance: ____ppg
1 g/cm3 = 8.45 lb/gal
1 lb / gal (ppg) = 0.11982 g/cm3
• Time of mud quart for mud drainage = ______ sec
• 𝜇 = 𝜌 𝑡 − 25
• 𝜇 =_____________ cp
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11. Precautions
1. Use care while filling the funnel with mud.
2. The stop watch should be used carefully and vigilantly
to record accurate flow time.
3. Wear relevant Personal protective equipment.
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12. Viva Voce
Q1)what are the applications of Marsh funnel?
Q2) why is Marsh Funnel the most common way to
determine viscosity? And why is viscosity so important in
drilling?
Q3) why is the mesh in the funnel used for?
Q4) what are the advantages of Marsh funnel over the
other viscosity instruments?
Q5) what are the limitations of Marsh funnel?
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