1. This experiment aims to determine the amount of filter loss and filter cake thickness using a standardized API test apparatus. 2. The student measured the filter loss over 30 minutes at room temperature and 100±5 psi using the API test apparatus, which has a fine screen to simulate the wellbore wall and allow measurement of deposited filter cake thickness. 3. Key factors that control mud loss include the volume of filtrate lost into the formation, thickness and strength of the filter cake, and differential pressure between the wellbore and formation. The ideal filtration results have minimal fluid loss and a thin, tough filter cake.

1. 1
Koya University
Faculty of Engineering
Petroleum Engineering Department
Third stage
Drilling Lab.
Lab No.: 8
Prepared by : Sarwar Salam
Group: B
Date of Experiment:-Feb. 10th
2016
Submitting Date:-Apr. 06th
2016
Supervised by: Mr. Pshtiwan –Mr. Mohammed
2015-2016

2. Drilling Lab. Funnel Viscosity
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The aim of this experiment is to determine the amount of the filter loss
and determining of the filter cake thickness above the fine screen
using the standardized API test apparatus.

3. Drilling Lab. Funnel Viscosity
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The complex drilling fluids represent 15 to 18% of the total cost (about $1
million) of petroleum well drilling. Their formulation and characterisation need
various techniques. The classical water-based muds (WBM), at least spud
muds, contained only water and clay but their performances, directly evaluated
by the stability of the system and the rheological and filtration properties, were
generally poor.
Current tendencies are to increase the WBM performances or to use
biodegradable additives in oil-based muds (OBM). Wellbore instability is the
largest source of trouble, waste of time and over costs during drilling. This
serious problem mainly occurs in shales (principally clays), which represent
75% of all formations drilled by the oil and gas industry. The remaining 25%
are composed of other minerals such as sand, salt, etc. The wellbore instability
is due to the dispersion of the clay into ultra-fine colloidal particles and this has
a direct impact on the drilling fluid properties (Charlez and Heugas, 1991).
The adverse effects of filtrates during oil well drilling may be reduced if the
mechanism of filtration through mud cakes is well understood. Considerable
efforts have therefore been made through empirical and theoretical studies to
formulate a robust filtration theory for predicting the effects of mud parameters
during drilling.
Most of the existing models are either too simplistic or rather complex. This
Experiment developed a robust approximate analytical filtration theory that
incorporated steady state and transient effects. The results show that in addition
to viscosity, transient effects during filtration greatly affect cake build-up and
filtrate volumes and that reduced filtrate volumes can be achieved when steady
state is achieved rather than unsteady state filtration process. (Mud
Engineering,2013)

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The low pressure test is made using standard cell under the API
condition of 100 + 5 psi for 30 minutes at room temperature. Another
special cell, will be used to measure filtration rate at elevated
temperatures and pressure. Filter press used for filtration tests consists
of four independent filter cells mounted on a common frame.
Each cell has its own valve such that any or all the cells could be
operational at the same time. Toggle valve on the top of each cell
could be operated independently for the supply of air for each
individual cell.
Special high pressure and high temperature filtration tests are run in
the laboratory simulating formation temperature and formation back-
pressure. (King Fahd University,2003)
(Figure 1 Filtration test apparatus layout) (King Fahd University, 2003)

5. 5
1. Loosen the T-screw until the filter cell can be removed from the
frame.
2. Remove the filter cell and disassemble it.
3. Assure that all parts of the filter cell are dry and clean.
4. Check to see that the rubber gasket in the base cap is evenly placed.
5. Check the filtrate tube in the base cap to be certain it is free of
obstruction.
6. Place the screen in the base cap with the wide rim up.
7. Place filter paper on the top of the screen.
8. Place the second rubber gasket on top of the filter paper.
9. Replace the cell body.
10. Turn the cell body clockwise until it securely fastens into the J
slots.
11. Check to see that the rubber gasket is evenly fitted into the top
cap.
12. Fill the filter cell within the drilling mud sample.
13. Check to see that the hole in the top cap is free of obstruction.
14. Place the top cap on the filter cell.
15. Place the cell body into the frame.
16. Tighten the T-screw securely.
17. Place a graduated cylinder under the filtrate tube and adjust the
support to keep the cylinder under the filtrate tube.
18. Close the pressure-relief valve until the pressure is 100 ± 5 psi.
Start timing immediately.
19. Allow the test to continue for 30 minutes.
20. Read and make note of the amount of filtrate in the graduated
cylinder to the nearest 0.1 cc

6. Drilling Lab. Funnel Viscosity
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1- What is the difference between Filter loss and filter
cake?
According to the type of formation and its specified
properties, any loss of drilling fluid from inside the well
bore into the porous and permeable formation (i.e.
Natural fractured, caverns and/or . fracture due to
exceeded pressure.. etc.) is called Fluid loss.
But Filter Cake is the layer of the solids deposited on the
wall of the well when drilling fluid is at rest (static) or
dynamic (circulating).
When the fluid loss occurs?
The fluid loss occurs when the hydrostatic pressure
of the mud column is greater than formation
pressure. By this according to the pressure drop
direction mud will loss into the formation.
3- What are the factors that control amount of loss?
The total quantity of mud loss depends on some
factors such as volume of filtrate into formation,
thickness and strength of the filter cake and the
differential pressure between inside well bore and
formation.

7. Drilling Lab. Funnel Viscosity
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4- What is the function of the fine screen in the bottom
of the API test apparatus?
What is actually the fine screen does is that acting
as Well bore wall which let the solid particles to be
deposited on and by the end of the experiment we
will measure the thickness of the filter cake which
approximately represents the situation down in the
hole.
5- What is the device used to examine the filtration
process in HPHT wells?
The filtration process in HPHT wells is much more
different and complex than in normal wells, due to
the extreme high pressure there will be a great
differential pressure.
so filtration can be determined using of high
temperature high pressure filter press apparatus.
6- What are the ideal specifications of filtration?
The ideal filtration specification is to have small
amount of filter loss (filter loss should as much as
possible be reduced). And also presents a thin and
tough mud cake to seal the formation pores and
fractures against further fluid losses.

8. Drilling Lab. Funnel Viscosity
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1- Mud Engineering (2014) Engineering educations
[Online] Available from:
http://www.eng.cu.edu.eg/users/aelsayed/mud%20en
gineering.pdf [Accessed:Apr.2nd 2016]
2-OATAO (2015), Open Archive Toulouse Archive Ouverte
(OATAO) [Online] Available from:
https://core.ac.uk/download/files/437/12043275.pdf
[Accessed:Apr.2nd 2016]
3- King Fahd University, Department of Petroleum Engineering
(2003) Drilling laboratory manual[Online] available from:
http://www.oilproduction.net/files/Drilling_engineering.pdf
[Accessed: Apr.2nd 2016 ] .
4- Investigation into the rheological and filtration
properties of drilling mud formulated with clays from
Northern Nigeria (2013), Journal of Petroleum and Gas
Engineering Vol. 4(1), pp. 1-13 [Online] Available from:
http://www.academicjournals.org/article/article1379672652
_Omole%20et%20al.pdf
[Accessed: Apr.2nd 2016 ]
5- MUD ENGINEERING (2013) MUD SERVICES ONGC,
ASSAM ASSET [Online] Available from:
http://petrofed.winwinhosting.net/upload/IAI/17-
20mar10/MudEng.pdf [Accessed: Dec 16th
2015]

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