Lecture# 06

Circulation
1 System
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Circulation
System
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Circulation System

Heart of the circulating system is the mud pumps

Consists of a piston reciprocating inside a cylinder

Describe as single acting if it pumps fluid on forward

stroke (Triplex pumps)

Double acting if it pumps fluid on both the forward

and backward stokes (Duplex)
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Triplex Pump
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Triplex Pump
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Duplex Pump
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Pump Liner
o Pump liners fit inside pump cavity

o Affect pressure rating and flow rate from pump

o For a given pump, a liner has same OD but with
different internal diameters

o Smaller liner (small ID) is used in deeper part of

well where need low flow rate but higher
pressure
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Volumetric Efficiency
o Mud contain little air and is slightly compressible

o Piston moves through a shorter stroke before

reaching discharge pressure

o Volumetric efficiency is always less than one

o 95% for triplex and 90% for duplex

o Due to power losses in drives, the mechanical

efficiency of most pumps is about 85%
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Hydraulic Horsepower
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Duplex Pump
Output
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Triplex Pump
Output
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Pump Factors

 In practice, it is convenient to express:

 Pump output in terms of how many gallons or

barrels for every stroke of pump
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Duplex
Pump Factor
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Triplex
Pump Factor
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EX# 01
Hydraulic Horsepower
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Ex# 01
Solution
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Drilling Fluid
Functions

 Control sub-surface pressures

 Remove cuttings from hole

 Cool and lubricate bit and drillstring

 Prevent walls of hole from caving

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Oil-Based
Mud
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Oil Based
Mud
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Foam
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Foam
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Drilling Mud Properties

o Mud Weight

o Funnel Viscosity

o Plastic Viscosity

o Yield Point

o Gel Strength

o Fluid Loss and Filter Cake

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Mud Weight

Unit:
pounds per gallon (ppg or lb/gal)

Alternatives:
Specific Gravity SG (g/cm3),Kpa/m,
psi/ft
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a. Mud Weight
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Mud Balance
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Mud Balance
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b. Funnel Viscosity

Unit:
Seconds per quart (sec/qt)

Alternatives:
Seconds per litre (sec/litre)
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Marsh Funnel
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Marsh Funnel
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Marsh Funnel
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Viscometer
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Plastic Viscosity
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Yield Point
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Gel Strength

o There are two readings for gel strengths, 10 second

and 10 minute with speed of viscometer set at 3 rpm

o Fluid must have remained static prior to each test

o Highest peak reading will be reported

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API Filter Press

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Fluid Loss & Filter Cake

 ml / 30 minutes at 100 psi (for API test)

 500 psi and BHT ( ºF) for high temperature/high

pressure (HTHP)

 Filter cake thickness is measured in 1/32"

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Filtration Process
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Filter Cake
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Filtration Process

 Mud should form a thin, flexible, impermeable layer

(filter cake) against the wall

 Lowvalue of filtrate loss cause minimum swelling of

clays and minimum formation damage
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Filter Cake

 Filter cake should be in region of 1/32” to 2 /32" and

should never be greater than 3/32“

 Filtration control additives include:

Starch
Carboxymethyl cellulose (CMC)
Polyanionic Cellulose (PAC)
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Solid Control Equipment

a. Screen separation devices

b. Settling separation in non-stirred compartments

c. Removal of gaseous contaminant

d. Forced settling by centrifugal devices

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Solid Control
Equipment

 Mud is made up of fluid (water, oil or gas) and solids

(bentonite, barite etc.)

 Solids removal system retain desirable components

of mud system by separating out unwanted drilled
solids and contaminants
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Solids in Drilling Fluids

Classified by specific gravity:

 High Gravity Solids (H.G.S.)

sg = 4.2
e.g. Barite

 Low Gravity Solids (L.G.S.)

sg = 1.6 to 2.9
e.g. Drilling Cuttings
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Solids in Drilling Fluids

Classified based on the size (μ)

 The smaller the particle size, the more

effect on fluid properties

 The smaller the particle size, the more

difficult to remove
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API Classification of
Particle Size
Solid Control Equipment
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Solid Control
Equipment
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Solid Control Equipment

a. Screen separation devices

b. Settling separation in non-stirred compartments

c. Removal of gaseous contaminant

d. Forced settling by centrifugal devices

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a. Screen Separation Devices

Shale shakers can remove up to 80% of
all solids from a drilling fluid

if the correct type of shaker is used and

run in an efficient manner
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Shale Shaker
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Shale Shaker
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Types of
Shale Shaker
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Shale Shaker
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Vibrating Assembly

 Types: Elliptical and Linear motion

 Elliptical shakers work better with water based

muds

 Linear motion shakers are more suited to oil based

muds

 Minimum of 3 shakers is recommended

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Solid Control
Equipment

a. Screen separation devices

b. Settling separation in non-stirred compartments

c. Removal of gaseous contaminant

d. Forced settling by centrifugal devices

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b. Settling Separation
in Non-stirred Components

 Solids control pits work on an overflow principle

 Sandtraps are fed by screened mud from shale

shakers

 Anylarge heavy solids will settle out here and will

not be carried on into e other pits
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Sand Trap Tanks

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Sand Trap Tanks

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Solid Control
Equipment

a. Screen separation devices

b. Settling separation in non-stirred compartments

c. Removal of gaseous contaminant

d. Forced settling by centrifugal devices

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c. Remove of Gaseous Contaminant

Gas entrapped in mud must be

removed

Maintain mud weight to a level needed

to control down hole formation
pressures
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Vacuum Degasser
(Mud/gas Separator)
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Vacuum Degasser

 Createa low internal pressure which allows gas-cut

mud to be drawn into degasser vessel

 Gas-cut mud flow in a thin layer over an internal

baffle plate
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Vacuum Degasser

Combination of low internal pressure

and thin liquid film

Gas bubbles to expand in size, rise to

surface of e mud inside vessel and
break from mud
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Vacuum Degasser

 As
gas moves toward top of degasser it is
removed by vacuum pump

 Removed gas is routed away from rig and is

then either vented to atmosphere or flared
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Solid Control
Equipment

a. Screen separation devices

b. Settling separation in non-stirred compartments

c. Removal of gaseous contaminant

d. Forced settling by centrifugal devices

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d. Forced Settling by
Centrifugal Devices

I. Desanders

II. Desilters

III. Mud Cleaners

IV. Centrifuges
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Principle of
Hydrocyclone
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I. Desander
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I. Desander

 Hydrocyclones with 6 in ID or larger

 Primary
use is in top hole sections when drilling with
water based mud to help maintain low mud weights
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I. Desander

 Prevents overload of desilter cones and increases

their efficiency by reducing MW and solids content
of the feed inlet

 Use if the sand content of mud rises above 0.5% to

prevent abrasion of pump liners
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I. Desander

 Never be used with oil based muds, because of its

very wet solids discharge

 Make a cut in 40 to 45 micron size range

 Witha spray discharge, underflow weight should be

between 2.5 to 5.0 ppg heavier than input mud
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II. Desilter
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II. Desilter

 Usedin conjunction with desanders to process low

mud weights

 Never be used with oil based muds

 Makes a cut in the 20 to 25 micron size range

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Typical Capacity
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d. Forced Settling by centrifugal Devices

I. Desanders

II. Desilters

III. Mud Cleaners

IV. Centrifuges
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III. Mud Cleaner

 Consists
of a battery of hydrocyclones placed
above a high energy vibrating screen

 Only use when it becomes impossible to maintain

low mud weights by use of the shale shakers alone
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Mud Cleaners

 Itis far more efficient to use desilters and process

underflow with a centrifuge than to use screens of a mud
cleaner
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Mud Cleaner
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Mud Cleaners
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Mud Cleaners
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Forced Settling by centrifugal Devices

I. Desanders

II. Desilters

III. Mud Cleaners

IV. Centrifuges
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IV. Centrifuge
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Centrifuge
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IV. Centrifuge

 Use centrifugal forces to remove heavy solids

from liquid and lighter components of mud

 Consists of a horizontal conical steel bowl

rotating a high speed
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Centrifuge

 Bowl contains a double-screw type conveyor which

rotates in same direction as steel bowl, but at a
slightly lower speed
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Thank You
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