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Petrochemical engineering

Notes: Mud filtration

1

Mud Filtration
Summary
Mud-filtration measurement is necessary for petroleum engineer in order to interpret there
behaviour and filter cake characteristic of a drilling fluid, in
...
The test consists of determining
the rate at which fluid is forced through the filter paper
...
The thickness of the solid filter cake deposited
is measured after the test
...
The API fluid
loss is conducted at surface temperature at 100 psi pressure, and is recorded as the number of
millilitres lost in 30 min
...
The
characteristics of drilling fluid are affected the types and quantities of solids in the fluid and
their physical and chemical interactions which, in turn, are affected by temperature and
pressure
...


Table (1) (HTHP):
Mud
coposition

Bentonite
+ water

Filter in 30
min (ml)
Mud
thickness
(1/32 inch)

18*2=36
4
...
thickness
(1/32 inch)

17
2
...
Polymer
20
2
...
Polymer
10
...
5

Bantonite +
water + 2g
polymer l
16
2
...
Polymer
9
...
9

Bentonite +
water+ 3g
...
6

Bentonite +water
+ 6g
...
8

2

Equipment’s











Filter Press (HPHT)
Standard filter press (LTLP)
Gas cylinder
Digital Calliper
...


 Both of filtrate volume and mud cake thickness drops considerably as we add more
and more Polymer
...

Recording the filtrate volume at different times up to 30 minutes might be a good idea
to examine the drilling time effect on the volume of filtration
...

Filtrate flow can be controlled by controlling mud cake thickness
...

The decreasing of filtrate volume reduces reservoir formation damage
...
In the
industry, it’s very common for engineers to add polymers to mud compositions as to effect
the volume of liquid forced through the mud composition
...
Filtration is a fundamental unit operation
aimed at the separation of suspended solid particles from a process fluid stream by passing
the suspension through a porous substance referred to as a filter medium
...
The fluid discharging from the medium is called
filtrate
...

The fundamental concepts of drilling fluids filtration and associated problems such as
formation damage are discussed in this chapter
...
This differential pressure provides the driving force
for mud movement
...
Massive loss
of mud into the formation usually does not occur except in fractured formations, because the
mud solids are filtered out onto the wall of the hole, forming a cake of relatively low
permeability, through which only filtrate can mainly pass
...
Therefore, both borehole stability and
formation damage are functions of the above process which is called the filtration behavior of
drilling fluids
...
High-pressure
high-temperature filter presses provide an efficient means of evaluating the filtration
properties of drilling fluids at high pressures and temperatures
...

Bentonite is an aluminium silicate and is very reactive towards water – swelling to several
times its dry mass volume on contact with water
...

These subunits are typically connected by covalent chemical bonds
...
The test in the laboratory consists of measuring the
volume of liquid forced through the mud cake into the formation drilled in a 30 minute period
under given pressure and temperature using a standard size cell
...


V∝√t

Drilling mud has been prepared by adding 140g Bentonite to 2 liters of water
...
The laboratory experiment was
carried out by giving a pressure to drilling fluid to 30 minutes
...
The experiment was repeated by adding different amount of polymer
...

When the amount of polymer increases, then volume of filtrate decreased, these is because of
the polymer added to the water molecules and the intermolecular bond becomes harder
...

(LTLP) test:
The equipment used in this experiment was standard API filter press
...
Filter
cake is formed by the constituents of drilling mud (Bentonite and water) which controls the
loss of liquid from mud
...

In each experiment, the thickness of mud cake and the volume of filter were measured
...
The
thickness of mud cake was same for the addition of different amount of polymers (1
...

Objectives
To Investigate how a difference is caused in filtrate amount and mud cake thickness when
adding different amounts of polymer to the mud composition

5

Equipment











Filter Press (HPHT)
Standard filter press (LTLP)
Gas cylinder
Digital Calliper
...

Stop watch, to measure ∆ filtrate every 30 minute
...
place the dial-type metal thermometer in the well in the heating jacket, preheat to 6ᵒc
2
...

3
...
Screw a valve stem into test cell on side opposite the cell cap, tighen the valve stem
completely
5
...

6
...

7
...
Slowly pus the cell cap into the cell, make sure the arrow on the cell cap lines up with
arrow on the cell body
...
Place the cell in the heating jacket, with the outlet or filter side of the cell pointed
down
...
Rotate the cell in the heating jacket, so that the pin in bottom of the heating well seats
into the hole, in the bottom of the cell
...
Transfer the treatment from the heating jacket to the treatment well within the cell
...
Connect the pressuring assembly to the top valve stem and lock it in place with the
rerating pin
...
Keeping the valve close
14
...

15
...

PART B-REPEAT ABOVE STEPS BY ADDING FLUID LOSS ADDITIVE TO THE
MUD AS THE FOLLOWING
1
...
Report on filtrate and mud
thickness
2
...
Report on filtrate and
mud thickness
3
...
Report on filtrate and
mud thickness
(LTLP)
Procedure for sing mud without additive
1
...

2
...
Place a dry graduate cylinder under the drain tube to receive the filtrate
...
Close the relief valve; adjust the regulator so that a pressure of 100±1
...
The last period begins at the time of pressure application
...
At the end of 30 minutes measure the volume of filtrate
...

6
...
1cm) as the API filtrate
...
Disassemble the cell, get rid of the mud, but take extreme care so not to disturb the
surface of the cake
...

8
...

9
...

PART B-REPEAT ABOVE STEPS BY ADDING FLUID LOSS ADDITIVE TO THE MUD
AS THE FOLLOWING
4
...
Report on filtrate and mud
thickness
5
...
Report on filtrate and
mud thickness
Add another 2g of polymer (MIL-PAC R) and mix thoroughly
...
1 HTHP
Mud
coposition

Bentonite
+ water

Filter in 30
min (ml)
Mud
thickness
(1/32 inch)

18*2=36

Table
...
thickness
(1/32 inch)

Bentonite
+water +
1g
...
1

Bentonite
+ water
17
2
...
5

Bentonite
+water +
2g
...
4
1
...
0

Bentonite
+water +
4g
...
7
0
...

polymer
10
1
...
Polymer
8
0
...


Discussion
It has been found in early work that the volume of fluid lost is roughly proportional to the
square root of the time for filtration
...
These results are what we expected to be honest,
as this process of thickening mud compositions is widely used in the petroleum industry
...

We can say that as we added more polymer to the mud composition, although there was a
decrease in mud cake thickness, there was also a decrease in filtrate amount
...

Overall the experiment went quite smoothly
...

From both experiments, it is clear that when the pressure and temperature increases the
volume of filtrate and thickness of mud increases
...

9
...
1mm these is because of the removal of water from the mud
but in the case Bentonite + water + 1g of polymer, the volume of filtrate 20ml was
comparatively less than Bentonite + water 36 and the formation of mud cake 2
...
In the case of bentonite + water + 4g of polymer, the
volume of filtrate was 12
...
09mm
...
The
polymer is attached to the water molecules
...
3 LTLP:
The above result shows that in the case of bentonite + water, the filtrate is 17 ml and the
thickness of the mud cake was 2
...
4 was
comparatively less than Bentonite + water and the formation of mud cake 1
...
In the case of Bentonite + water + 4g of polymer, the volume of
filtrate was 9
...
9mm This is because of the addition of
polymer in water molecules so the intermolecular bond will be stronger
...


Conclusion


The experiment was carried out successfully, the filtrate and mud cake thickness was
determined
...








The decreasing of filtrate volume reduces reservoir formation damage
...

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
...

The addition of polymer to the mud composition, result in less of filtration and mud
cake thickness decreases
...


12

Nomenclature
Quantity

Unit

Pressure

Bar

Temperature

o

Filtration

Ml

Thickness

mm

C

References
1
...

3
...

5
...

Adam T
...
, (3 audition) 1989 “Applied Drilling Engineering”
William C Lyons
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M Telford, R
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Sheriff, L
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Geldart, ‘Applied Geophysics’, 2nd Edition, pg 645,
Cambridge University Press, UK
6
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wikipidia
...
Class Handouts and notes
8
...
depts
...
edu/preweb/research/capr
s/caprspaers/SPE 70043%/20011pdf accessed on 7-12-05; updated Dec 2005
...
http://www
...
com/doc/37148309/Drilling-Engineering
10
...
J
...
Drilling Engineering; A complete well planning approach
...

11
...
wikipedia
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ASME Shale Shaker Committee (2005) Drilling Fluids Processing Handbook Gulf
Professional
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Machando, V
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Jose, etc (1990)
...
SPE latin America, Petroleum Engineering Conference, 14-19
October 1990
...

14
...
utm
...
pdf
rd

13



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