This document discusses drilling fluid systems. It provides information on: - Drilling fluid functions such as providing hydrostatic pressure, keeping the drill bit cool, carrying cuttings, and limiting corrosion. - Types of drilling fluids including water-based mud, oil-based mud, and synthetic-based mud. - Components of an active drilling fluid system including pumps, pits, and the annular space in the wellbore. - Factors that determine drilling fluid volume such as rig size and well design/depth. - Rheological behavior models for drilling fluids based on relationships between shear stress and shear rate. - Uses of drilling fluid rheology including calculating friction and surge pressures. - Instruments for

2. The drilling fluid system commonly known
as the (mud system) is the single component
of the well construction process that remains
in contact with the well bore throw the entire
drilling operation.

3. Drilling – fluid –systems are designed and formulated
to perform efficiently under expected well bore
conditions.
Advances in drilling – fluid technology have made it
possible to implement a cast.effective fit for purpose
system for each interval in the well construction
process.
Drilling fluid is used to aid the drilling of boreholes into
the earth. Often used while drilling oil and natural gas
wells and on exploration drilling rigs drilling fluid are also
used for much simpler boreholes such as water wells.

4. The three main categories of drilling fluids are:

5. The main functions of drilling fluid
include providing hydrostatic pressure to
prevent formation fluid from entering into
the well bore, keeping the drill bit cool and
clean during drilling, carrying out drill
cuttings, suspending the drill cuttings while
drilling is paused and when the drilling
assembly is brought in and out of the hole.
The drilling fluid used for particular job is
selected to avoid formation damage and to
limit corrosion.

6. the active drilling – fluid system
comprises a volume of a fluid that’s
pumped with specially designed
mud pumps from the surface pits,
through the drilling strain exiting at
the bit up the annular space in the
well pore, and back to the surface
for solids removal and maintenance
treatments as needed.

7. The capacity of the surface
system usually is determined by
the rig size and rig selection is
determined by the well design for
example, the active drilling- fluid
volume on a deepwater well might
be several thousand barrels.

8. Much of that volume is required to fill the
long drilling riser that connect the rig floor
to the sea floor.
By contrast , a shallow well on land might
only require a few hundred barrels of fluid to
reach its objective.

9. Fluid behavior is divided according to the
observed behavior between the shear stress (Ʈ)
and shear rate (ƴ) with the temperature and
pressure into two types :

10. This type of fluid exhibit a linear relationship between
shear stress (Ʈ) and shear rate (ƴ) (i.e the viscosity is
constant).

11. A non-Newtonian fluid is defined as a fluid does not
have a constant viscosity (i.e the relationship between Ʈ
and ƴ is not linear )

12. Can be classified into two general types :

13. In this type of fluid the magnitude of viscosity is not
effected by the duration of shear (i.e the shear- stress at
constant temperature is solely dependent on the rate of
the shear of this temperature ) this type of fluid can be
classified into three types:

15. Generally, two types of flow can recognized.

16. The rheology is defined as the
study of deformation and flow of
matter.

17. 1. Calculating friction in pipe or annulus.
2. Calculating surge pressure when running or pulling pipe.
3. Estimating hole-cleaning efficiency.
4. Determining the jet nozzle velocity and friction loss at bit.
5. Determining the equivalent circulating density of the
drilling fluid.

18. The best method to select the best rheological model
which fits the actual rheogram of fluid , which depends on
the absolute average percentage error (AAPE) between
the measured and calculated values of shear – stress .
They considered that the model which gives the lowest
(AAPE) as the best rheological model.

20. Is an instrument used to measure viscosity and gel
strength of drilling mud.
Fann vg meter
This device consist of a rotational cylinder and bob
instrument.
Six speeds of rotation (3,6,100,200,300 and 600 rpm)
are available in all instruments (some devices have 12
speeds).

21. Fann vg meter is called (Direct indicating viscometer)
because at a given speed, the dial reading is a true
centipoise viscosity.
For example at 300 rpm, the dial reading (511sec - 1) is
a true viscosity

22. Fann vg meter

24. Mr. GHASSAN H. ALI