Preperation of Drlling mud of desired density

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

2. Experiment # 02:
• Objective:
• Preparation of drilling mud of desired density.
• Given Statement:
• Prepare a drilling mud of density 11 ppg , using barite and
fresh water. What amount of barite should be added in 200
mL of water to have the required density mud?
• Density of Water = Do = 8.33 ppg
• Density of Barite = Da = 35 ppg
• Required Density = Df= 11 ppg
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3. Apparatus
• Mud Mixer
• Barite
• Salt
• Water
• Measuring cylinder
• Graduated Beaker
• Mud Balance
• Weighing Balance
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4. Related Theory
• Mud Balance:
• It consists of a graduated beam with a bubble level and a
weight slider along its length and a cup with a lid on one end.
• The cup is used to hold a fixed amount of liquid so it can be
weighed.
• A slider-weight can be moved along the beam, and a bubble
indicates when the beam is leveled.
• Density is read at the point where the slider-weight sits on the
beam at level.
• Calibration is done using a liquid of known density (often
water) by adjusting the counter weight.
• Typical mud balances are not pressurized, but a pressurized
mud balance operates in the same manner.
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5. Mud Balance
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6. 5/5/2021

7. • Bentonoite:
• The mineral bentonite can be found all over the world. It is
formed from weathering volcanic ash. It has some exceptional
properties:
• when stirred into water, it demonstrates a so-called thixotropic
reaction. It reacts as a fluid when mechanically stressed, for
example shaken or stirred. However, it hardens in quiescent
condition because its viscosity increases.
• The most common use of bentonite is in drilling fluids.
• The bentonite in the flush fluid lubricates and cools the cutting
tools while protecting against corrosion.
• As the drilling fluid generates hydrostatic pressure in the
borehole, it hinders fluid and gas penetration. The drilling
liquid conveys the drill cuttings to the surface. When the purge
pumps have idle periods, the thixotrophy of the bentonite
hinders the stone material from dropping back into the drilled
shaft.
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8. Barite:
• Barite is the primary, naturally occurring, barium-based
mineral.
• The chemical formula for barite is BaSO4. It has a high
specific gravity of 4.50 g/cm3.
• The overwhelming majority of the barite that is mined is used
by the petroleum industry as a weighting material in the
formulation of drilling mud.
• Barite increases the hydrostatic pressure of the drilling mud
allowing it to compensate for high-pressure zones
experienced during drilling.
• The softness of the mineral also prevents it from damaging
drilling tools during drilling and enables it to serve as a
lubricant.
• The American Petroleum Institute (API) has established
specifications for the use of barite in drilling mud.
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9. Density and Specific
Gravity
Material Specific Gravity Density
Water 1 8.33
Bentonite 2.5 20.3
Barite 4.5 35
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10. Procedure
1) First of fall calculate the weight of barite for mixing in
200 mL of water to prepare 11 ppg mud by using
Equation 2.1
W= 42 𝐷𝑎 (
𝐷𝑓−𝐷𝑜
𝐷𝑎−𝐷𝑓
) (2.1)
Where ,
W= Required weight of additive material, lb/bbl
Da = Density of Additive, ppg
Df= Desired density of new mud, ppg
Do= Density of original liquid used to prepare mud (water
or anyother), ppg
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11. 2) Exact weight of barite is measured using digital weighting balance.
3) Selected volume of Water is measured using graduated beaker.
4) Measured quantities of barite and water are taken and mixed for 3-5
min in electric mixer.
5) Now measure the density of the mud by using mud balance. So
firstly, calibrate Mud balance by using water as reference.
6) After calibration, completely fill the cup with completely agitated mud
sample to be tested
7) Put the lid and rotate until firmly seated, making sure some mud
must expel through the lid hole.
8) Wipe away the mud from the outside of the cup and lid.
9) Place the mud balance in its position.
10) Move the rider until the graduated arm is level indicated by the
bubble.
11) Note down the density reading, adjust the error if present and then
convert it into Specific Gravity (SG).
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12. Observation and
Calculations
Using Equation W= 42 𝐷𝑎 (
𝐷𝑓−𝐷𝑜
𝐷𝑎−𝐷𝑓
) , lb/bbl
Where ,
W= Required weight of additive material, lb/bbl
Da = Density of Additive= 35 ppg
Df= Desired density of new mud= 11 ppg
Do= Density of original liquid used to prepare mud= 8.33 ppg
1lb/bbl = 2.85 x 10^-3 grams/ml
• W = ? grams/mL
• W = ? Grams/200 mL
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13. Precautions
• It is essential that all parts of mud balance should be
kept clean if accurate results are to be obtained.
• Calibration is necessary for mud balance.
• All air bubbles which may trap in the cup must be
eliminated.
• Wear relevant Personal Protective Equipment (PPE).
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14. Viva Voce
1)Using the mud weights (ppg) obtained from your sample
in experiment # 01,calculate how much hydrostatic
pressure that each sample will exert on a formation at a
depth of 10,000 ft ?
2) What is the difference between Over-balance and
Under-balance?
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