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

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Aim of experiment:The aim of this experiment is to determine the change

in the viscosity of drilling fluid.

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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)

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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.

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Apparatus & materials:

 

Mud balance Electronic balance Beaker

Syringe Electric mixer & steel vessels

Water Bentonite

Marsh Funnel & quart Stop Watch 5

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 around70℉.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 be26±0.5 s.

Procedures:6

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.

Discussion:Q1) what are the applications of Marsh funnel?

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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.References:

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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.

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