Adding a liquid phase (water) to drilling fluid (mud) to Decrease the density or Decrease drilled-solids concentration

1. Koya university
Faculty of engineering
Petroleum department
Drilling engineering
Mud Dilution
Bakhtiar star M.
Lab EXP.(3)
Third stage
Supervised by: Mr. pishtwin jaf
Date: 26/nov/2015

2. Aim
Adding a liquid phase (water) to drilling fluid (mud) to
Decrease the density or Decrease drilled-solids
concentration

3. THEROY
You sometimes need to reduce your mud weight in hole. The
method to reduce mud weight is dilution. The concept of dilution
is to add light weight fluid into heavy fluid and when they mix
together whole drilling fluid weight will decrease. The light
weight fluid frequently used are fresh water, sea water, base oil,
diesel, synthetic oil, etc which are normally your based fluid.
All of the physical properties in a drilling fluid are affected when
the solid content increases
Dilution refers to the process of adding a liquid phase to a drilling
fluid to decrease the drilled-solids concentration. Dilution is used
in several ways., dilution may be the principal method of keeping
drilled solids to a reasonably low level. This is an expensive
solution to the problem. (Growcock, 2005)
We must dilution and decrease the density of mud we use in the
field when the pressure of fracture is less than pressure hole
(hydrostatic pressure), -If Formation Pressure < Hydrostatic
pressure then it is under pressured and while pressure fracture >
hydrostatic pressure so we should do dilution .

4. Usually dilution is used after processing by solids-removal
equipment to dilute drilled solids remaining in the drilling fluid.
Dilution may be added as a clean drilling fluid or as the liquid
phase of a drilling fluid with the other necessary drilling fluid
ingredients, usually through a chemical barrel and a mud hopper.
In this discussion, dilution will refer specifically to the clean
drilling fluid necessary to decrease drilled-solids concentration.
(Annis, 1996)

5. Introduction to experiment
Mud balance is one of the most sensitive and accurate field
instruments available for determining the density or weight-
per-unit-volume (specific gravity) of drilling fluids.
Bentonite is an absorbent aluminium phyllosilicate, impure
clay consisting mostly of montmorillonite. The absorbent clay
was given the name bentonite by Wilbur C. Knight in 1898
Mud mixture this device used for mixture well water and
betonies
.

6. Betonite
water

7. Calibration
1. Remove the lid from the cup, and completely fill the cup
with water.
2. Replace the lid and wipe dry.
3. Replace the balance arm on the base with knife-edge resting
on the fulcrum.
4. The level vial should be centered when the rider is set on
8.33 ppg. If not, add to or remove shot from the well in the
end of the bream.

8. Procedure
Preparing of mud
1. Remove the lid from the cup, and completely fill the cup
with the mud to be tested.
2. Replace the lid and rotate until firmly seated, make sure
some mud is expelled through the hole in the cup, by tapping
the lid a few times
3. put a finger on the lid’s hole then Wash or wipe the mud
from the outside of the cup.
4. Place the balance arm on the base, with the knife-edge
resting on the fulcrum.
5. Move the rider until the graduated arm is level, as indicated
by the level vial on the beam.
6. At the left-hand edge of the rider, read the density on either
side of the lever in all desired units without disturbing the
rider.
7-then we add water a constant volume we want
8-then we mix the water with previously prepared mud by mixture
machine

9. 9- Replace the lid and rotate until firmly seated, make sure
some mud is expelled through the hole in the cup, by tapping
the lid a few times
10- Put a finger on the lid’s hole then Wash or wipe the mud
from the outside of the cup
11- Place the balance arm on the base, with the knife-edge
resting on the fulcrum.
12- At the left-hand edge of the rider, read the density on
either side of thelever in all desired units without disturbing
the rider.

10. DISCUSION
In this discussion we talk about sometimes need to reduce
your mud weight in hole. The method to reduce mud
weight is dilution. The concept of dilution is to add light
weight fluid into heavy fluid and when they mix together
whole drilling fluid weight will decrease. The light weight
fluid frequently used us fresh water.
So we need to do dilution at Formation Pressure smaller than
Hydrostatic pressure then it is under pressured and while
pressure fracture greater than hydrostatic pressure , One of its
most important function is to provide the hydrostatic pressure
to balance formation pressure , This is why the mud dilution
is so important .
Also, Dilution not only will supply the water needed to wet
these solids, but also will provide the necessary water to keep
these particles dispersed. The further apart the active solids
are kept , When a dilutant is added, the percentage of
concentration of solids in a given volume is reduced, the
mechanical friction among particles is decreased.

11. References
1-Annis, M.R. and Smith, M.V. (1996) Drilling Fluids Technology. Texas: Exxon
Company.
2- Darley, H.C.H. and Gray, G.R. (1988) Composition and Properties of Drilling and
Completion Fluids. 5thedn. Houston: Gulf Publishing Company.
3- Growcock, F. and Harvey, T. (2005) „Drilling Fluids‟ in ASME, Shale Shaker
Committee. Drilling Fluids Processing Handbook. Oxford: Gulf Professional
Publishing, pp. 15-68.
4-Rabia, H. (2001) Well Engineering and Construction. Halesowen: ENTEC.
5- Stroud, B. K., Application of Mud-Laden Fluid, Oil Weekly June
5,1925, pp.29-30
6-Sonny Irawan, Ahmad Zakuan Ahmad Azmi and Mohd. Saaid, Corn
Cobs and Sugar Cane Waste as a Viscosivier in Drilling Fluid, Pertanika
J. Sci. & Technol. 17 (1): 173 – 181 (2009)