1. The experiment aimed to prepare a mud with a known density and then increase its density by adding barite. Barite has a high specific gravity of 4.2, which allows mud density to be increased up to 21 pounds per gallon. 2. Procedures involved mixing bentonite and water to form a mud, then weighing and adding barite while stirring. The mud balance was used to check densities before and after barite addition. 3. Barite is the most common weighting agent due to its ability to significantly increase mud density up to 21 ppg, control formation pressures, and stability. It is also readily available and chemically inert.

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Petroleum department
3rd stage
Group (A)
Drilling Lab
2nd
Experiment:
Mud Weighting
Date of experiment: November 19th
2015
Supervised by:
Mr. Pshtiwan Jaf
Prepared by:
Muhammad Faisal

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Aim of experiment:
The aim of this experiment is to prepare a typical mud with
known density and then modify its physical properties (density) by
adding a limited amount of barite to it and increase the muds
density, and this procedure is called Mud Weighting.

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Theory:
By far, the principal use for barite is as a "weighting agent" in
oil and natural gas drilling. In this process, barite is crushed and
mixed with water and other materials. It is then pumped into the
drill hole. The weight of this mixture counteracts the force of the
oil and gas when it is released from the ground. This allows the oil
and gas rig operators to prevent the explosive release of the oil
and gas from the ground. Currently, over 75% of barite
consumption in the U.S. is for this drilling application. However, the
consumption in drilling "mud" fluctuates from year to year, as it is
dependent on the amount of exploration drilling for oil and gas,
which in turn depends on oil and gas prices. (Ariffin, 2015)
Mud weighting with barite has many advantages such as:
• Easy to use.
• Density increases to 2.52 S.G (21 pounds per gallon).
• Low addition rate to achieve high densities
• Controls formation pressures
• Improves borehole stability
• Chemically inert
• Does not react with other additives
• Limited particle breakdown. (Kogel, 2006)

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Introduction:
In this experiment we create a mud with a known density then
we increase the density of the mu by adding barite to it which is a
very common used weighting material in the oil fields. In this
experiment we used the same apparatus and instruments that have
been used in the last experiment in addition to barite. Barite
powder has a specific gravity of 35 and bentonite has a specific
gravity of 20.8 which means barite is a very good weighting
material. In the lab we should be very careful and accurate when
dealing with barite because a single gram more or less of barite
can affect the result of the mud balance which is an instrument
used to determine density and specific gravity. Every single
member of the groups should take part in the experiment, and
should use the apparatus and the necessary materials with total
responsibility.

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Apparatus & materials:
Mud balance Electronic balance Beaker
Syringe Electric mixer & steel vessels
Water Barite Bentonite

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Calibration:
1. Remove the lid from the cup.
2. Fill the cup with fresh water around 70°F (21°C).
3. Put the lid back on the cup, (water should come out from the
lids hole).
4. Set the rider on 8.3 ppg or 1 specific gravity.
5. Add or remove steel shot from the Shot well until the
instrument is in balance and the bubble in the level rests in the
center of the level glass.

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Procedures:
1. Weigh 20.048 g of bentonite on the electric balance.
2. Pour 491.8 cc of water into a 500 ml beaker.
3. Pour the water into two vessels and stir the water with the
mixer, then slowly add the bentonite to the stirring water.
4. Leave the mixer running for few minutes till, then mix the mud
in one of the vessels with the mud in the other.
5. Fill the clean, dry cup to the top with the mud sample.
6. Place the lid on the cup and set it with a gentle twisting
motion. Be sure that some mud is expelled through the hole
in the cap.
7. Cover the hole in the lid with a finger and thoroughly dry the
entire balance.
8. Place the balance on the knife edge and put the rider on 8.53
ppg (the expected mud density) and wait till the cup and arm
are balanced as indicated by the bubble.
9. Pour the mud in the cup into the vessels again and stir the
mud with the mixer.
10. Weigh 54.5 g of barite with the balance.
11. Slowly add the barite to the stirring mud.
12. Fill the mud balance cup with the modified mud.
13. Place the lid on the cup. Be sure that some mud is
expelled through the hole in the cap.

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14. Place the balance on the knife edge and put the rider on
9.2 ppg (the expected mud density) and wait till the cup and
arm are balanced as indicated by the bubble.
15. Clean and dry the mud balance when finished.
Discussion:
Weighting materials are substances with high specific gravity
which can be added to the mud to increase its density, usually to
control formation pressure. Barium sulfate (BaSO4) or Barite is by
far the most common weighting material used in drilling fluids. It
has an API defined specific gravity of 4.2, which makes it possible
to increase mud weight up to 21 ppg .It is cheap and readily
available. However, suspension of barite requires high gel strength
and viscosity. Barite is chemically inert and insoluble, It is usually
colorless or milky white, but can be almost any color, depending
on the impurities trapped in the crystals during their formation. It
is unusually heavy for a non-metallic mineral. Barite is not the only
weighting material to increase muds density. There are many other
materials that can be used, but the reason of commonly using
barite is because of the advantages it has. Barite is of significance
to petro physicists. In laboratory mud weighting is a very sensitive
experiment so we should be accurate to avoid any human or
machine errors.
Q1) what is the chemical composition of Barite?
A1) Barium sulfate (BaSO4).

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Q2) why is barite the most common weighting material?
A2)
 By increasing slurry density, it helps restrain high formation
pressures and improve mud displacement.
 It is applicable in deep, high-temperature wells.
 The Environmental Protection Agency (EPA) does not classify
barite additive as a hazardous waste.
Q3) what are the applications of barite?
A3)
• Increase mud density up to 21 ppg (2.5 g/cc).
• Control formation pressure.
• Stabilize the borehole.
• Prepare solids-laden plugs for well control application.
Q4) what are the natural sources of barite?
A4) most barite is mined from layers of sedimentary rock which
formed when barite precipitated onto the bottom of the ocean.
Some smaller mines utilize barite from veins, which formed when
barium sulfate was precipitated from hot subterranean waters. In
some cases, barite is a by-product of mining lead, zinc, silver, or
other metal ores.
Q4) what are the alternatives of barite?
A4) Possible substitutes for barite, include other similar minerals,
such as celestite (strontium sulfate, SrSO4) and iron ore,but barite

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continues to be the preferred commodity for this application as
long as barite production remains strong.
Q5) what is the common error that we face during mud weighting?
A5) when we add the barite powder to the bentonite mud some of
the powder is lost in the air.
References
Caenn, R., Darley, H. C. H. & Gray, G. R., 2011. Composition and Properties
of Drilling and Completion Fluids. s.l.:Gulf Professional Publishing.
Ariffin, D. K. S., 2015. LIDAR PAGES. [Online]
Available at:
http://lidarmax.altervista.org/lidar/SCIE%20CHIMICHE/BARIO%20generici/
Baryte.pdf
[Accessed 25 November 2015].
Kogel, J. E., 2006. Industrial Minerals & Rocks: Commodities, Markets, and
Uses. s.l.:SME.
Lyons, W. C., 2011. Standard Handbook of Petroleum and Natural Gas
Engineering. 2 ed. s.l.:Gulf Professional Publishing.

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