Ministry of Higher Education وزارة التعليم العالي والبحث العلمي
and Scientific Research جامعة كربالء
Karbala University
كلية الهندسة
College of Engineering
قسم هندسة النفط
Petroleum Engineering Department
"mud weight "
A report submitted by the students:
سجاد كريم هاشم
كرار صبار عجيل
كرار شاكر يوسف
Supervising Doctor, Abdul Karim Al-Rubaie
Drill Lab
lecturer's name (Mustafa Mahmoud)
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Objectives
1-Aim This determine and prepare a mud and find a density by
mud balance and to know the relationships between weight and
density Vw *dw +Vs * ds = Vm *dm (d): density (v): volume
2-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.
Theory
The density of the drilling fluid must be controlled to provide adequate
hydrostatic head to prevent influx of formation fluids, but not so high
as to cause loss of circulation or adversely affect the drilling rate and
damaging the formation.
A device to measure density (weight) of mud,other liquid. A mud
balance consists of a fixed-volume mud cup with a lid on one end of a
graduated beam and a counterweight on the other end. A slider-weight
can be moved along the beam, and a bubble indicates when the beam is
level. Density is read at the point where the slider-weight sits on the
beam at level Drilling fluid -mud - is usually a mixture of water, clay,
weighing material and a few chemicals. Sometimes oil may be used
instead of water, or oil added to the water to give the mud certain
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desirable properties. Drilling fluid is used to raise the cuttings made by
the bit and lift them to the surface for disposal. But one of the major
functions of a drilling fluid includes providing hydrostatic pressure to
prevent formation fluids from entering the wellbore. To ensure that the
hydrostatic pressure balances out with formation pressure and that the
wellbore is stable, the mud density has to be taken into consideration.
Higher formation pressure requires higher mud density (this can be
achieved by adding more barite to the drilling fluid) and vice versa.
Using an incorrect drilling fluid (in terms of its mud density), can result
in a formation damage thereby leading to a well blowout. also we can
use other material for preparing mud with different material also we
can get a different specific gravity and density (craft,2008)
Normal pressure gradient by water is equal to (0.433 psi/ft) and equal
to 433 psi/1000 ft.
Test Equipment
The Baroid Mud Balance as shown below is used to determine density
of the drilling fluid. The instrument consists of a constant volume cup
with a lever arm and rider calibrated to read directly the density of the
fluid in ppg (water 8.33), pcf (water 62.4), specific gravity (water =
1.0) and pressure gradient in psi/1000 ft. (water 433 psi/1000 ft.)
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Mud weight / Mud density
The weight or density of drilling fluid is measured using two devices
1. API mud balance
This device is used with water drilling fluid and in shallow wells at
moderate temperatures and pressures and the unit of
measurement is ppg
API mud balance
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2. Pressurized mud balance
It is used with oil basic mud , especially in deep wells with high
temperatures and pressures. It is used to measure the weight of
drilling fluid with high accuracy under the conditions of temperature
and pressure. It is also used to calculate the weight of cement and its
measurement units are ppg.
Pressurized mud balance
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mud balance device
Procedure Calibration
1. Remove the lid from the cup, and completely fill the cup with water.
2. Replace the lid and wipe dry.
3. Replace the balance arm on the base with knife-edge resting on
the fulcrum.
4. The level vial should be centered when the rider is set on 8.33
ppg. If not, add to or remove shot from the well in the end of the
bream.
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Procedure
Preparing of mud
1. Remove the lid from the cup, and completely fill the cup with
the mud to be tested.
2. Replace the lid and rotate until firmly seated, making sure
some mud is expelled through the hole in the cup.
3. Wash or wipe the mud from the outside of the cup.
4. Place the balance arm on the base, with the knife-edge resting
on the fulcrum.
5. Move the rider until the graduated arm is level, as indicated by
the level vial on the beam.
6. At the left-hand edge of the rider, read the density on either
side of the lever in all desired units without disturbing the rider
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DISCUSION
Q/what will effect of temperature on (ideal test)?
-The temperature effected on density of liquid, so we should be
doing this experiment in room temperature to get an accuracy result
Q/what’s the factors get you error?
*if you don’t use pure water content a many impurity that
effected on density * Quality of Bentonite *accuracy of the mud
balance and weighting balance
Q/why the Mud density so important?
Mud has many functions<including:
-transporting cutting
-Serves as a medium for formation logging
-transmitting power to bit nozzles or turbines
-cooling and lubrication of bit and drill string.
-reducing formation damages
-protecting cutting
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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%20g
enerici/ 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
