This document describes an experiment to measure filtrate loss and mud cake thickness of a drilling mud sample using a hydraulic filter press according to API standards. The key steps are: assembling the filter press cell with the mud sample, applying 100 psi of pressure via a dead weight piston system for 30 minutes, and measuring the volume of filtrate collected and thickness of the mud cake formed. Maintaining control of filtration rates is important for drilling operations to prevent reservoir damage.

1. Drilling Engineering-I
Pet-E-211L
Lab Instructor :
Engr. Muhammad Awais Qureshi
Department of Petroleum &
Gas Engineering 5/5/2021

2. Experiment # 09
• Objective:
1) Measurement of filtrate loss and mud cake thickness of
drilling mud sample using dead weight hydraulic filter
press considering API Standard.
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3. Apparatus
• Hydraulic Filter Press,
• Pressure Gauge,
• Water
• Drilling Mud Sample
• PPE’s (Personal Protective Equipments)
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4. • Mud Cake :
• Mud cake is the solid particles deposited on the pores of the formation
creating a form of barrier when the drilling fluid is forced against the
formation under an applied pressure.
• Mud filtrate:
• Mud filtrate is the liquid part of the mud which can pass through a
medium and become separated from the mudcake. The mud filtrate,
the liquid part of the mud, invades the formation. Mud filtrate is the
fluid of the drilling mud that filters into the formation during invasion.
• Fluid Loss:
• The leakage of the liquid phase of drilling fluid, slurry or
treatment fluid containing solid particles into the formation matrix.
Fluid-loss additives are used to control the process and avoid potential
reservoir damage.
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Related Theory

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6. • 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 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.
• 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, i.e.
V ∝ 𝑡
• The two commonly determined filtration rates are the
low-pressure, low-temperature and the high-pressure
high-temperature.
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7. Hydraulic Filter Press
• The assembly is composed of a water reservoir requiring about
a pint of fresh water for each test, piston and cylinder, dead-
weight, delivery pressure gauge, two check valves, and a
bleed-off valve.
• The assembly is operated by raising the dead-weight and
piston, drawing water from the reservoir through a check valve
into the cylinder.
• When weight is released, the piston forces water through the
outlet check valve, to the delivery pressure gauge, and to the
unfilled part of the filter press cell.
• When the system is closed, the dead-weight causes the piston
to exert a continuous pressure of 100 psi (6.9 bar) on the water
in the piston chamber and against the mud in the filter press
cell.
• A bleed-off valve is provided to enable prompt release of the
pressure on the cell at the completion of the test. The hydraulic
system has a volume sufficient to run the usual 30-minute
filtration test without further attention from the operator.
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8. Hydraulic Filter Press
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9. Managing the pressure –
Dead Weight Piston Gauge
• Before placing the dead-weight hydraulic filter press in
operation, fill the water reservoir and cylinder to the top
with clean, fresh water. Repeat this operation
occasionally to provide sufficient water to lubricate the
O-ring packing at the top of the cylinder. Next, open the
bleed-off valve, place the piston with weight attached in
the cylinder and release the dead-weight allowing the
piston to travel a full stroke. Refill the reservoir with
clean, fresh water. Close the bleed-off valve and the unit
is ready for operation.
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10. Dead Weight Tester-
Principle
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11. Hydraulic Pressure
Assembly
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12. Measurement Procedure
1) Before beginning a test, make sure each part of the cell is
clean and dry particularly the screen. Examine the gaskets
for distortion and wear and make sure the screen is free of
sharp edges or tear out.
2) To assemble the test cell, begin by turning the base cap
upside down and placing a rubber gasket inside it. Then,
place the screen, and a sheet of filter paper followed by
another gasket. Finally, place the cell body into the base cap
and turn it to lock it in place.
3) Pour the freshly agitated mud sample into the cell, leaving
about 0.5” (13 mm) of empty space at the top.
4) Place a rubber gasket inside the top cap. Make sure it is
seated at the way around the cap. Then place the top cap
onto the cell body and place the entire cell into the frame.
Secure the cell with the T-screw
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13. 5) Place a clean, dry graduated cylinder under the filtrate
tube.
6) Attach the hose from the dead-weight hydraulic
assembly with clean and fresh water.
7) Make sure the bleeder valve is closed before
pressurizing the cell.
8) Raise the dead weight about a foot and allow it to settle.
In about two-thirds of a stroke, the pressure gauge will
indicate 100 psi.
9) Maintain 100 psi on the pressure gauge and observe
filtrate collection in receiving cylinder.
10)After 30 min, measure the volume of filtrate collected.
Shut off the flow from the pressure source
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14. Demonstration
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15. Observation and
Calculations
• Thickness of Mud Cake = ____________ mm
• Filtrate loss = ______________ ml
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16. Precautions
1. While working, and operating with pressure, take care.
2. Wear relevant Personal protective equipment.
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17. Viva Voce
1. Describe how the filter cake is formed on the walls of a
hole during a normal drilling operation.
2. What are the factors controlling the rate of filtration?
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