Drilling engineering laboratory manual by Muhammed Jamal Awl

Technical College of Engineering
Petroleum and Energy Engineering Department
Drilling Engineering Laboratory Manual
Prepared by
Mohammed Jamal Awl
September-2019
E-mail: mohammed.jamal@koyauniversity.org

1 | P a g e
Preface
The main objective of this manual is to demonstrate the basic
techniques of formulating, testing and analysing the properties
of drilling fluid (mud).
This manual consists of ten experiments for measuring the
physical properties of drilling fluid such as mud weight
(density), funnel viscosity, rheological properties (viscosity,
yield point and gel strength), pH measuring, sand content
measuring in the mud and filtration characteristics.

2 | P a g e
Contents
List of figures.............................................................................................................3
Nomenclatures ...........................................................................................................4
Convert Unites ...........................................................................................................5
Experiment No. 1 (Mud Density) ..............................................................................6
Experiment No. 2 (Mud Weighting)..........................................................................9
Experiment No. 3 (Mud Dilution) ...........................................................................10
Experiment No. 4 (Effect of Temperature on Mud Density)...................................11
Experiment No. 5 (Funnel Viscosity)......................................................................12
Experiment No. 6 (Viscosity and Yield point) ........................................................14
Experiment No. 7 (Gel strength)..............................................................................18
Experiment No. 8 (Hydrogen Ion Concentration (pH))...........................................19
Experiment No. 9 (Sand Content)............................................................................23
Experiment No. 10 (Filtration) ................................................................................25
Bibliography.............................................................................................................29

3 | P a g e
List of figures
No. No.Name of the figure Page
1 Typical mud balance 7
2 Marsh Funnel 13
3 Newtonian and non-newtonian 16
4 Multi-rate Viscometer 17
5 pH Paper and pH meter 21
6 pH Meter 22
7 Sand content kit 25
8 Standard API Filter press 28

4 | P a g e
Nomenclatures
Symbol Meaning
bbl barrel
cc cubic centimeter
ft feet
ppg pound per gallon
cp centipoises
gal gallon
gpm gallon per minute
Ib pound
in inch
pH power of hydrogen
min minute
sec second
psi pound per square inch
hr hours
ml milliliter
gm gram
L liter
kg kilogram
pcf pound per cubic feet

5 | P a g e
Convert Unites
Unit Multiply by Converted unit
kg 1000 gm
L 1000 ml
ml 1 cc
gm/cc 8.33 ppg
hr 60 min
hr 3600 sec
poise 100 cp
Ib 453.592 gm
bbl 42 gal
bbl 159 L
gal 3.78 L
gm/cc 62.4 pcf

6 | P a g e
Experiment No. 1 (Mud Density)
Introduction
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.
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.).
Figure 1: Typical Mud balance

7 | P a g e
Equipment 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 8.33ppg (1gm/cc). If
not, add to or remove shot from the well in the end of the beam.
Test Procedure
1- Preparing a mud by mixing bentonite and water.
2- Remove the lid from the cup, and completely fill the cup with the mud to be
tested.
3- Replace the lid and rotate until firmly seated, making sure some mud is expelled
through the hole in the cup.
4- Wash or wipe the mud from the outside of the cup.
5- Place the balance arm on the base, with the knife-edge resting on the fulcrum.
6- Move the rider until the graduated arm is level, as indicated by the level vial on
the beam.
7- 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.
Test Calculation:
Prepare (---cc) of (---ppg) mud,
How much bentonite and water need?

8 | P a g e
Material gm/cc ppg
Water 1 8.33
Bentonite 2.5 20.8
Barite 4.2 35
ρ1V1 + ρ2V2 = ρmVm
Vm = V1 + V2
ρ = m / V

9 | P a g e
Experiment No. 2 (Mud Weighting)
Introduction
The density of a mud is increased by adding barite, a commercial grade of barium
sulphate. Barite is used as a standard weighting agent because of its low cost, high
specific gravity, inertness, and low abrasiveness. Its specific gravity averages about
4.2. Pure barium sulphate has a specific gravity of 4.5, indicating that some
impurities are present in the commercial grade.
Applying weighting process to increase the hydrostatic pressure, at that time kick
and blowout not happen.
Test Procedure
1- Prepare a mud by mixing bentonite and water.
2- Measure the density of the mud by mud balance.
3- Adding (---gm) of barite to the mud.
4- Repeat measure the density of the mud, as you see the density of the mud is
increased.
Test Calculation
How much barite should be added to increase the density of mud to (---ppg)?

10 | P a g e
Experiment No. 3 (Mud Dilution)
Introduction
Dilution refers to the process of adding a liquid phase to a drilling fluid to decrease
the drilled-solids concentration. Dilution is used in several ways. If no solids-
control equipment is used or if the equipment is used ineffectively, dilution may be
the principal method of keeping drilled solids to a reasonably low level.
Applying dilution process to decrease the hydrostatic pressure of mud before it
reaches to the fracture pressure.
The main goal of dilution process is to avoid mud losses and formation damage.
Test Procedure
2- Measure the density of the mud by mud balance.
3- Adding (---cc) of water to the mud.
4- Repeat measure the density of the mud, as you see the density of the mud is
decreased.
Test Calculation
How much water should be added to decrease the density of mud to (---ppg)

11 | P a g e
Experiment No. 4 (Effect of Temperature on
Mud Density)
Introduction
Liquids expand when heat is applied and are compressed by pressure. Therefore,
the density of the fluid decreases with increasing temperature. But increases with
increasing pressure. As a drilling fluid is pumped downhole, its density is changed
by these temperature and pressure effects.
Test Procedure
2- Measure the density of the mud by mud balance at room temperature (25C).
3- Heating the same mud to (50C) by heater.
4- Measure the density of the heated mud, and compare the density of the mud
for both temperatures.
Test Calculation:
Prepare (---cc) of (---ppg) mud
Mud Density (at 25 C) =?
Mud Density (at 50C) =?

12 | P a g e
Experiment No. 5 (Funnel Viscosity)
Introduction
The viscosity of a fluid is defined as its resistance to flow. The desired viscosity
for a particular drilling operation is influenced by several factors, including mud
density, hole size, pumping rate, drilling rate, pressure system and requirements,
and hold problems.
For field measurements the marsh funnel has become the standard instrument.
Test Equipment
The Marsh Funnel is a device that is common to every drilling rig. Details of the
Marsh Funnel and receiving cup are shown in Figure 2. The viscosity is reported in
seconds allowed to flow out of the funnel. API specifications call for 1500 ml and
(946 ml) out.
Figure 2: Marsh Funnel

13 | P a g e
Fill the funnel to the bottom of the screen (1500 ml) with water at 70 ºF (plus or
minus 0.5 ºF) time of outflow of (946 ml) should be 26 seconds plus or minus 0.5
second.
Test Procedure
2- With the funnel in an upright position, cover the orifice with a finger and
pour the freshly collected mud sample through the screen into a clean, dry
funnel until the fluid level reaches the bottom of the screen (1500 ml).
3- Immediately remove the finger from the outlet and measure the time
required for the mud to fill the receiving vessel (measuring Jug) to the (946
ml) level.
4- Report the result to the nearest second as Marsh Funnel Viscosity.
Test Calculation
Funnel Viscosity of water =?
Funnel Viscosity of mud =?
Funnel Viscosity of mud (Correct) =?

14 | P a g e
Experiment No. 6 (Viscosity and Yield point)
Introduction
Two types of fluid characterizations are:
1. Newtonian (true fluids) where the ratio of shear stress to shear rate or viscosity
is constant, e.g. water, light oils, etc.
2. Non-Newtonian (plastic fluids) where the viscosity is not constant, e.g. drilling
muds, colloids, etc.
Rheological properties of mud:
1- Plastic Viscosity (PV): Viscosity is defined as the resistance of a fluid to flow,
this resistance made by the size and amount of solid particles in the mud. Also it is
measured as the ratio of the shearing stress to the shear rate.
The unit of PV is cp.
PV for Newtonian fluid (Water) is constant.
But PV for Non-newtonian fluid (Mud) is not constant.
2- Yield Point (YP): is the amount of force that needs to circulate mud after
stopping circulation.
The unit of YP is Ib/100 ft^2 and Pascal.
YP for Newtonian fluid is equal to Zero.
YP for Non-newtonian fluid has a value greater than Zero.
3- Apparent Viscosity: actually it has not and it is the ideal viscosity is one-half of
the dial reading at 600 rpm in Bingham plastic model.
4- Gel Strength

15 | P a g e
Figure 3: Newtonian and Non-Newtonian fluids
Test Equipment
The Baroid Rheometer is a coaxial cylindrical rotational viscometer, used to
determine rheological properties of mud. It has fixed speeds of 3, 6, 100, 200, 300
and 600 RPM that are switch selectable with the RPM buttons.

16 | P a g e
Figure 4: Multi-rate Viscometer
1- Place a calibration fluid in the cup, tilt back the upper housing of the
rheometer, locate the cup under the sleeve (the pins on the bottom of the cup
fit into the holes in the base plate), and lower the upper housing to its normal
position.
2- Turn the knurled knob between the rear support posts to raise or lower the
rotor sleeve until it is immersed in the calibration fluid to the scribed line.
3- This calibration fluid has a chart, RPM’s are known.
4- Adjusting Manual Rotation of Sleeve till the RPM readings reaches the chart
number.

17 | P a g e
Test Procedure
2- Place a recently agitated sample in the cup, tilt back the upper housing of the
rheometer, locate the cup under the sleeve (the pins on the bottom of the cup
fit into the holes in the base plate), and lower the upper housing to its normal
position.
3- Turn the knurled knob between the rear support posts to raise or lower the
rotor sleeve until it is immersed in the sample to the scribed line.
4- Stir the sample for about 5 seconds at 600 RPM, and then select the RPM
desired for the best.
5- Wait for the dial reading to stabilize and Record the dial reading and RPM.
6- Stir the sample for about 5 seconds at 300 RPM, and then select the RPM
desired for the best.
7- Wait for the dial reading to stabilize and Record the dial reading and RPM.
Test Calculation
1. Plastic Viscosity (μp) (cp) = 600 RPM reading – 300 RPM reading
2. Apparent Viscosity (μa) (cp) = 600 RPM reading / 2
3. Yield Point (Ib/100 ft2) = 300 RPM reading – Plastic viscosity

18 | P a g e
Experiment No. 7 (Gel strength)
Introduction
Gel strength: is the ability of mud to suspend the rock cuttings when circulation
was stopped. The Baroid Rheometer is also used to determine the Gel strength, in
lb/100 sq. ft., of a mud.
Common types of Gel Strength:
A) Initial Gel Strength: it means Gel Strength 10 sec.
B) Final Gel Strength: it means Gel Strength 10 min.
Other types are 30 min and 16 hours.
The unit of Gel strength is Ib/100 ft^2 and Pascal.
Test Procedure
1- Stir a sample at 600 RPM for about 15 seconds.
2- Turn the RPM knob to the STOP position.
3- Wait the desired rest time (normally 10 seconds or 10 minutes).
4- Switch the 3 RPM knob to the GEL position.
5- Record the maximum deflection of the dial before the Gel breaks, as the
Gel strength in lb/100 ft2.
Test Calculation
Gel Strength (10 sec) =?
Gel Strength (10 min) =?

19 | P a g e
Experiment No. 8 (Hydrogen Ion
Concentration (pH))
Introduction
The acidity and the alkalinity of the drilling fluid can be measured by the
concentration of the (H+) ion in the fluid.
-If (H+) is large (1 x 10-1), then the (OH-) hydroxyl concentration is very low (1 x
10-13), the solution is strongly acidic.
-If the (OH-) concentration is (1 x 10-1) very high then (H+) concentration is very
low then the solution is strongly alkaline.
PH Ranges:
- In most cases pH between (7 to 9.5).
- If PH above 9.5, viscosity will increase that are out of proportion for good
drilling properties. Some times for minimizing shale problems use PH above 9.5.
-Problems of acidic mud:
1) Corrosive pipes.
2) When drilling in high H2S, should be increase the pH of fluids (above 10)
and using sulfide scavenging chemical (zinc carbonate or zinc chromate).
Note: H2S is not corrosive, but in the presence of moisture, O2 and CO2, it
becomes corrosive.

20 | P a g e
Additive for increasing pH Additive for decreasing pH
Lime Sodium bicarbonate [HNa]
Caustic Soda Stearic Acid [CH3(CH2)16COOH]
Soda ash
KCl
NaCl
For example: using Soda ash ¼ pound to ½ pound per 100 gallons.
There are two ways for measuring pH:
1- pH Paper: problem is inaccuracy.
2- pH Meter: most accurate method.
Figure 5: pH paper and pH meter

21 | P a g e
Test Equipment
The pH Meter is a device used to measure the pH value of the mud.
Figure 6: pH meter
1- Put the Electrode into a beaker of water.
2- Wait to stabilize the device in a number.
3- If it is not equal to (7.3), find the error and use this error for pH of mud.
Test Procedure
2- Put the Electrode into a beaker of mud.
3- Wait to stabilize the device in a number.
4- Adding error to the mud result to find corrected pH value of mud.

22 | P a g e
Test Calculation
pH (water reading) =?
pH (mud) =?
pH (mud corr.) = ?

23 | P a g e
Experiment No. 9 (Sand Content)
Introduction
Is defined to be that portion of the drilling mud solids whose size is greater than
200 mesh (74 microns). The test can be used to give a qualitative, relative
indication of the solids removal equipment effectiveness or power.
Note: Desander make separations between 45 to 74 microns, Desilter separate
solids between 15 to 45 microns and Shale shaker separate solids greater than 74
microns.
Problems of sand in the mud:
1) Sand particles can be highly abrasive, and can cause excessive wear of pump
parts, drill bits, and pipe connections.
2) Excessive sand may also result in the deposition of a thick filter cake on the
walls of the hole.
3) It may settle in the hole around the tools at that time circulation is stopped.
Test Equipment
The Sand Content Kit is an apparatus used to determine the volume percent of sand
in the mud.

24 | P a g e
Figure 7: Sand content kit
Test Procedure
1- Prepare a mud by mixing bentonite and water and contain sand.
2- Pour mud into the glass measuring tube until it fill up to the mark labeled
“mud to here” then add water to the mark labeled “water to here” cover
mouth of the tube with thumb and shake them.
3- Pour this mixture through the screen, being careful to wash everything out of
the tube with clear water through the same screen. Wash sand retained on
screen with a stream of water to remove all mud and small particles.
4- Fit funnel down over top of the screen, invert slowly turning tip of funnel
into mouth of glass measuring tube, and wash sand back into tube with water
on the back side of the screen, allow the sand to settle.
5- Read the scale of sand settled in the glass measuring tube as the sand content
of the mud.
Test Calculation
Sand % =?

25 | P a g e
Experiment No. 10 (Filtration)
Introduction
Loss of fluid (usually water and soluble chemicals) from the mud to the formation
occurs when the permeability is such that it allows fluid to pass through the pore
spaces. As fluid is lost, a build-up of mud solids occurs on the face of the wellbore
called filter cake (mud cake).
The loss of liquid from a mud due to filtration is controlled by the filter cake
formed of the solid constituents in the drilling fluid. Two types of filtration occur;
dynamic, while circulating and static, while the mud is at rest.
Lost Circulation
During drilling operations, it is possible to experience lost circulation, lost
circulation is a situation when drilling fluid losses downhole or flow the mud into a
formation, and very expensive problem to deal with, it occurs when the drill
encounters natural fissures, fractures, or caverns, also called thief zone, and drilling
fluid or drilling mud will be lost in these formations.
Types of loses:
1) Seepage loss: mud volume loses are around 25 bbl/hr.
2) Partial loss: mud volume loses are around 150 bbl/hr.
3) Total loss (Complete loss): there is no mud returning back to surface.
Reasons of loses:
1- Geological effect
2- Engineering effect
Treatment for loses:
1- Applying dry (blind) drilling [only for total loss]
2- Preparing Lost Circulation Materials (LCM).
LCMs are: (Fibrous, Flaked, Granular and Expan Gel).

26 | P a g e
Excessive filtration and thick filter cake build up are likely to cause the
following problems:
1. Tight hole, causing excessive barrier.
2. Increased pressure, due to reduced hole diameter.
3. Differential sticking, due to an increased pipe contact in filter cake.
4. Excessive formation damage and evaluation problems with wireline logs.
Relations between:
1- Volume of loses and Pressure: before creating filter cake, directly
proportional and, after creating mud cake no change.
2- Volume of loses and Temperature: directly proportional because when
temperature increased, viscosity decreased, when viscosity decreased mad
cake decreased and volume of lose increased
3- Volume of loses and Time: volume of loses is directly proportional with
square root of time.
Test Equipment
Standard API Filter Press is an apparatus used to determine volume loses of mud
and thickness of mud cake.

27 | P a g e
Figure 8: Standard API Filter Press
Test Procedure
2- Connect all parts of filter cell; these parts are base cap, rubber gasket,
screen, filter paper, rubber gasket, cell and rubber gasket from bottom to top.
3- Fill the filter cell within the drilling mud sample.
4- Place the top cap on the filter cell and tighten by T-screw.
5- Place the graduated cylinder under the filtrate tube and close the pressure
relief valve until the pressure is 100 ± 5 psi. Start timing immediately.
6- Allow the test to continue for 30 minutes.
7- Calculate the volume flow rate of the mud after 30 minute.
8- Release pressure and Remove the cell from the frame by loosening the T-
screw.
9- Remove all parts of filter cell.
10- Measure the thickness of mud cake on the filter paper.

28 | P a g e
Test Calculation
Time (min) V loss (ml)
10
20
30
Filtration rate (ml/sec) =? After 30 min
Thickness of mud cake =?
Draw a curve between V loss and √ Time?

29 | P a g e
Bibliography
1. Amoco Production Company (2010) Drilling Fluids Manual. Available at:
petroshaggy.blogspot.co.uk/2010/08/drilling-fluids-manual-amoco-
production.html (Accessed: 9 September 2019).
2. Annis, M.R. and Smith, M.V. (1996) Drilling Fluids Technology. Texas: Exxon
Company.
3. Darley, H.C.H. and Gray, G.R. (1988) Composition and Properties of Drilling
and Completion Fluids. 5thedn. Houston: Gulf Publishing Company.
4. Growcock, F. and Harvey, T. (2005) „Drilling Fluids‟ in ASME, Shale Shaker
Committee. Drilling Fluids Processing Handbook. Oxford: Gulf Professional
Publishing, pp. 15-68.
5. Rabia, H. (2001) Well Engineering and Construction. Halesowen: ENTEC.

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