Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Petrochemical
fluids

Engineering:

Drilling

1|Page

Summary
In the world of petroleum and chemical
engineering, there is multiple function

the drilling is the resistance to the
flow in theory the greater the resistance
the higher the viscosity of the drilling
fluid
...


transport under cutting to the sub
surface, provides hydraulic power to the
drill bit
...

The drilling fluid is often called
drilling fluid drilling mud fluid
...
During the development of the
well hydrostatic pressure is formed and
the drilling fluid keeps from entering
into the borehole enhancing the drilling
fluid will allow the clean and the
transport of the under cutting be easier
because of the density and viscosity in
enhance
...
Also the
drilling fluid is use to avoid corrosion,
the strata of the reservoir is analysed
in order to prepare the correct ratio of

The properties of the drilling fluid;
density of the mud, marsh viscosity,
plastic, apparent viscosity, yield point,
gel strength, shearometer and the pH
level was determined
methods and equipment

using

different

The density of the drilling fluid is
directly proportional to the pressure
hence the density controls the pressure
The additives barite has high specific
gravity than bentonite, therefore adding
barite will increase the mud weight and
it is one of the best enhancers when
controlling the pressure and it ’ s more
efficient
The pH of the drilling fluid affects the
solubility of the organic thinners and
the spreading of clays present in the mud
Experimental objective
The

measurement

of

the

density

of

the

using

viscosity

the barite and polymers
...
The density of the drilling is
monitored constantly during drilling
operations, especially in areas known as

The

measurement

and

shearometer and the pH level
Why do we need to measure mud density?

the over pressure zones
...
Checking for

used
and
some
the

drilling fluid from contaminating the
reservoir this is often used at the final
stage of drilling operation this is only

the pH of the drilling fluid is important,
the standard pH of a drilling fluid is
between 8 and 9 therefore justifying as

used then because of the cost of oil
based
drilling
fluid
...
If the pH of the
drilling fluid goes in the acid region
problem will arise in terms of corrosion
of the pipes, pH level is measured paper

important function is to keep the
pressure of the borehole in check
...


to test the pH level
...

There
are
several
functions of drilling fluid, clean the
cuttings, lubricate the drill bit, cool

important therefore regular test to the
recycled drilling fluid is important this
will give the property of the fluid so
adding more or reducing will help

the drill bit, transport the cuttings and
stabilize the borehole
...
The standard protocol drilling
practice
for
the
maintaining
the

the under cuttings to the sub surface and
dropping the them in the surface disposal
areas, improving the recovery of the
system
...
The drilling fluid is
circulated continuousness through the

be toxic, workers will be exposed to the
drilling fluid for most of the time
therefore the additives all the way to

wellbore to control the pressure and to
transport the under cutting to the
surface
...

Cleaning the drilled hole is important so
the annular velocity can be low as 20

still one of the important function of
the drilling fluid
...
The properties of the mud must
be specific for the well and reservoir

drill bit longer more on the evaluation
of the performance of the drilling fluid
to function efficiently depends on the
main properties of the drilling fluid,

drilled one of the important property is
mud weigh this balances and control
formation pressure and more or less helps

density (mud weight) which is measured
using a baroid, viscosity is measured
using a marsh funnel this is only one

the stability of the borehole
...


drilling fluid
...
ft
...
The experiment
conducted using the experiment us done in
two different duration 10 seconds and 10

affect the drilling rate therefore
damaging the formation
...

The mud weight is directly relative to

minutes this will give an indication of
how much gelation that will occur in two
different durations after circulation and

the amount of pressure exerted at the
bottom of the well hole
...


static
...
The drilling fluid density
helps understand the flow, in addition

the drilling fluids are either colloids
or emulsion which behaves like non
Newtonian fluids which differs from

the mud helps maintain the stability of
the wellbore this concludes the pressure
control and the prevention of wall

Newtonian fluid hence the viscosity is
not constant but varied with the rate of
shear therefore the plastic fluid depends
on the rate at which the shear is

collapse
...


Mud viscosity

Yield point

Viscosity is the resistant of flow,
that’s causes friction through layers of

The yield is the theoretical measure of
the electro chemical or attractive forces
in the mud inflow conditions
...
The
particular
highlighted
including mud

desired viscosity for a
drilling
operation
is
by different parameters,
density, hole size, pumping

rate, drilling rate, pressure system and
requirement and hold problems
...
During the
development
of
the
field
standard
viscosity measurement equipment is marsh
funnel, V-G meter a direct indicator

properties of the drilling fluid,
electrical environment of the solids
all the forces for the yield point
...


the

of

undercutting

to

pH hydrogen Ion concentration
the acid and the alkaline level of the
drilling fluid can be measured using a
simple pH paper this will indicate the
acid or alkaline level of the drilling

4|Page

fluid (H= ions or 1*10-1 therefore OHions), if the concentration of the OHion is very low then the drilling fluid
is very acidic and if the OH- ion is very
high the drilling fluid is very alkaline
...

The standard pH of a drilling fluid is
between 8 to 9 pH therefore the drilling
fluid is an alkaline
Example
pH= log(1/1x10-7) = -log [1x10-7 ] = -(-7)
= 7
...
3*Vo(PrPo)/Pb-Pf

Mud density

Vo is the original volume of water

Density of the drilling fluid can be
defined as this weight of the mud

Po is the original density of the mud
Type’s of drilling fluid

Density expressed mathematically as:
Water based mud; the composition of the
Density p = mass of the fluid (M)/ Volume
of the fluid (V)
Unit pounds per gallons (ppg)
Density of the drilling at a specific
gravity
The density of the drilling can be
expressed:
Specific gravity of the mud = Density of
the mud pm/ Density of the water pw
Plastic viscosity
Plastic viscosity follows the equation:
PV = O600 - O300 (cp)
0600 is the shear rate at viscometer deal

drilling
fluid
is
participles
are
suspended in a water or brine
...
Oil is emulsified
is already therefore oil is a continues
phase
...
Foaming agent are added to remove
minor inflow of water to the drilling
fluid

reading O600 rpm
O300 is the shear rate at viscometer dial
reading of 300 rpm

Yield point

5|Page

Experimental diagrams
Baroid Mud balance
The experiment will be conducted using two different mud components, just standard bentonite and water and the other bentonite with water
and the added additives
One of the important mud properties is the density of the mud (weight), if the mud weight exceed the specific fracture pressure of the well
formation, the well formation might fracture therefore a large quantity of mud will be lost in the system through the fractures this
commonly referred to as mud circulation lost
...
If the mud weight is to low the hydrostatic pressure compared to the formation fracture
pressure this will cause the drilling fluid in the formation to flow upwards into the surface which is commonly referred to as formation
kick and can lead to serious problems like blowouts if the foreign fluid reaches the surface uncontrolled
3

Baroid mud balance manufacture error within the area of ± 0
...
1 g/cm

3

3

Setting for the baroid mud weight measurement is used more on fresh water
...
33 lbm/ft (1g/cm ) at 70
F (20 C)
Experimental procedures
Pre check the equipment for any contamination; make sure the cup is clean and dry before filling up with the drilling fluid
-

Fill the cup with the drilling fluid to the top and place the lid on top and allow any drilling fluid to be exerted through the hole
in the cap to free trapped air or gas, wipe any excess mud on the side of the cup

-

Place the baroid into the balancing beam, the instrument must be balance a spirit is located on the instrument, balance the
instrument till the bubble is roughly in the centre of the reader

-

Read the density of the rider at the side towards the knife edge, there are two readings

-

Report the density to the nearest 0
...
5 lbm/ft

3

6|Page

Baroid Mud balance

The baroid mass balance is a devie that is widely used in
the petroleum field that measures the density of the
drilling fluid, in order to accurate measure the the
fluid make sure all of the excess air in the cup is full
remove therefore the final value matches the barite
equation
...
1 greater
than the expected value

7|Page

Viscosity measurement, Mud rheology
To measurement and gather the data on a materials viscosity this highlight the specific properties needed for the manufacture to produce
the correct drilling fluid this will give the best product dimension
...
The interrelation between the rheology and other
product dimensions often makes the measurement of viscosity the most important and sensitive or convenient way of detecting changes in the
density of the drilling fluid, the stability of the suspend solids and molecular weight
Viscosity measurement using marsh funnel
Marsh funnel is a standard instrument fo4r routine measurement of viscosity
...
5 seconds
Experimental procedure
Pre experiment check, check the instrument for any damages make sure the instrument is clean to avoid contamination
-

Cover the orifice with a finger and pour a freshly mixed drilling fluid sample through the screen to filter out rocks, upright fill
the funnel until the fluid level is in contact with the screen

-

Use a stopwatch to measure the duration, quickly remove the finger and measure the time required for the mud to fill the receiving
3

vessel to mark (949 cm )
-

Report the reading to the nearest second as marsh funnel viscosity

8|Page

Marsh funnel

The mash funnel instrument is used to measure the
viscosity of the drilling fluid, the instrument only
measure the viscosity of the fluid not anything further
for example plastic viscosity however its widely used in
the oil field because it ’ s an accurate device and
provides a quick value

9|Page

Shearometer
2

Shearometer is used to measure the shear strength of the drilling fluid (lbf/100ft or KPa), the typical use for this test is for evaluation
of static aged drilling fluid and generally left at high temperature for several hours, the experiment conducted is left for ten minutes
and ten seconds, and temperature was not taken into account
...
For the initial shear strength quickly lower the tube over the
scale support and make sure the tube is not in contact with the support fully and placed it over the drilling fluid
...
For the drilling fluid viscosities which may vary from
different condition and environmental flow, the instrument is called a rheometer the viscometer in only measures less than one flow
condition
...

The drag caused by the relative motion is called viscosity
...
002 mPa
...
0038 mm /s
...
The
direct viscometer measures the plastic viscosity, yield point and the gel strength
...
To check the vessel apply gentle pressure to make sure the pins are all aligned
- The vessel containing the drilling fluid is placed on the stage such that it is aligned #on the holes, this is 3ft below the mud sample
cup
- the stage is adjusted therefore the sample drilling fluid is in line with scribed line on the rotor sleeve and locking knob was turned
clockwise to secure the assembly
- With the gear shift rod fully immersed in the sample drilling fluid, the motor speed switch was moved towards the sample
...
The viscosity of the mud can be calculated from the
values obtained by the shear rate
- Change the rotation setting of the drilling fluid by the two remaining low speed 3 rpm and 300 rpm as well as the high speed range of 200
rpm 6 rpm and 600 rpm
- The rotor stopped spinning while the fluid is still in the vessel with the motion in clockwise direction, now for the second part of the
experiment the motion of the rotation is turned anti clock wised the reading of the value is done manual, the drilling fluid experience
initial friction before rotating smoothly
- The maximum friction force was recorded
...
The pH level as the logarithm of the activity of
dissolve hydrogen ion which is positive charges (h+)
...
The pH scale is not an absolute scale it is the relative to a set standard solution whose pH is established by international
agreement
...
A solution with less than 7 is considered acidic and a pH level
more than 7 is considered an alkaline
...
These components generally occur naturally in food chemistry such as strawberry, blue berry, tea, cherries and flower pigments
...
A typical pH meter of a special
probe connected to an electronic meter that measures and displays the pH reading

15 | P a g e

pH paper diagram

The pH paper is to measure the hydrogen ions, the
drilling fluid must be 8 or 9 pH level
...
5, during
drilling minerals will change the pH level of the
drilling fluid therefore might interact with the
reservoir and the main problem corrosion inside the pipe

16 | P a g e

The experimental test result and derived results obtained from test 1 – 5 are as follows
Results

Mud Compositions
Mud parameters

Bentonite + Water

Bentonite + Barite + Water

Mud weight (ppg)

8
...
1

1
...
1

Marsh viscosity (sec)

40

42

Plastic viscosity (cp)

6

6

Apparent viscosity

16

17
...
5

13
...
0

9
...
6

formation pressure will have an influx of
fluid into the well bore, mud lost
circulation, formation instability and pipe
stuck
...
In order to get the
correct and effective value for the

drilling fluid is the viscosity, like the
first experiment two type of drilling fluid
was used varying from density
...
To unsure the accuracy of the
experiment after adding the bentonite to
the water no lumps or solid impurity must

check any changes in the properties of the
fluid this does not provide in depth
information as to why the viscosity of the
drilling fluid has changed but judging from

be visible this alter the density of the
drilling fluid and will change the readings
and data collected
...
Different instrument is used to
find out the viscosity properties; apparent

density of the drilling fluid sample an
instrument was used, baroid mass balance
was used to measure the density of the
first drilling fluid and for the second

viscosity, plastic viscosity and yield
point, variable speed rheometer is used to
measure in depth values of the fluid
viscosity this measures the resistance of

experiment barite was added to the drilling
fluid and the drilling density increase to
9
...
Six speeds was measured

fluid in order to enhance the property,
polymers are typically used to increase the
thickness of the mud cake thus increasing
the viscosity of the drilling fluid

categories in high speed and low speed also
the location of the rotor (low, middle and
high)
...

The first test has lower density than the

barite drilling fluid is mixed, the shear
stress to the rate of shear strain is
greater than the non-enhance drilling fluid,

second experiment with the barite, higher
fluid density cause the pressure in the
formation of the borehole
...

The
Bingham theory highlight the yield point is

into the formation, the excessive pressure
will lead to mud loss circulation to the
formation therefore operation will have to

a Newtonian fluid and the plastic viscosity
is a non-Newtonian fluid
...
When the fluid density increase the
amount of pressure needed to move the fluid
up the borehole also increase, leading to
high pressure pump required this will
significantly increase the cost of overall
drilling
cost
...
1g more than
expected for this error human inaccuracy
can
be
expected
during
the
second

hydrostatic pressure does not balance the

19 | P a g e

measurement of the density of the fluid the
baroid mass balance, not all of the excess
air was release on top of the lid therefore
the inaccuracy of the reading can be

drill bit can be stuck and the formation of
the borehole can collapse
...
Drilling fluid can be treated
like a base (alkaline) the pH level of the
drilling fluid will affect the viscosity,
bentonite is least affected if the pH if

plastic viscosity by mechanically removal
of the drilling solids at the surface
however there are limits on the viscosity
value
...
5 however any pH
level above the mentioned numbers may cause
the viscosity to increase
...
The two experiments
highlighted that there are an increase in
pH level but not significant non barite
fluid 9
...
5 pH both pH
level is perfectly expectable and well in
good range of the required level
...
Transporting the under
cutting of the well is determined by the
property of the drilling fluid, to measure
the this factor shearometer is used to
measure the gel strength of the drilling
fluid the instrument is a simple cup with
the measurements on the middle and a
aluminium tube, the unit for this test is
LBS/ft the cup is filled with the drilling
fluid and the tube is dropped the height of
the tube is read
...
5 (12
...
0) and for the barite
drilling fluid there was a significant
increase by 3
...
The change in
property in both experiment highlight the
capability
of
the
mud
transporting
undercutting to the surface, if the
cuttings are not properly disposed the

20 | P a g e

Conclusion
From all of the experiment the following
conclusion can be shown:
- The change in density the overall change
in the efficiency of the mud in proportion
is affected in terms of the weight of the
mud, balancing the pressure in the well
formation
and
preventing
blowout
is
calculated by the density of the drilling
fluid
- Gel strength is proportional to the cuts
therefore the proper properties to hold the
under cuttings if the drilling fluid is
wrong the operation will stop at any time
during the drilling progress
- The pH mud of the drilling fluid is
important in terms of maintaining the pipes;
too acidic drilling fluid
corrosion within the pipes and
level affects the solubility of
compounds and the spreading of

can cause
also the pH
the organic
the clay in

the mud
- Barite has a high specific gravity than
bentonite therefore barite increase the
weight of the mud and one of the best
additives in terms of controlling the
pressure more efficiently
- Density of
proportional to

the mud is directly
the pressure hence the

density controls the pressure

21 | P a g e

Nomenclature

PV

Plastic Viscosity

YP

Yield Point

ρf

Final Mud Density

ρo

Original Mud Density

ρB

Barite Density = 32
...
3

22 | P a g e

Reference
W
...
E
...
P
...
C
...

Gel Strength as Related to Carrying
Capacity of Drilling Fluids
...
Society of petroleum
Engineering
Introductory
Mud
Engineering Handbook, experiment 1
drilling
fluid
properties,
experimental procedures
http://www
...
com/doc/37148309/
Drilling-Engineering
http://www
...
com/doc/21775297/
Introduction-of-Drilling-Fluid-inOil-Gas-Indutry-Wikipedia
http://etd
...
edu/docs/available/e
td-10032005131910/unrestricted/Shelton_thesis

---