mehul csd presentation
TRANSCRIPT
BY : MEHUL JAIN
3rd year B.Tech.
UCE,RTU,KOTA
1. CEMENTATION
2. TYPES OF CEMENTATION
3. CEMENT SLURRY DESIGN AND
TESTING
4. SUMMRY
> Oil well cementation is the
process of mixing of a slurry of
cement, cement additives and
water and displacing it down the
casing, tubing or drill pipe to a
pre specified point in the well.
Secure and Support the casing in the hole.
To restrict fluid movements between formations
(Zone Isolation).
Stop the movement of fluid into regular or
fractured formations ( lost circulation ).
To protect the casing from corrosion.
Withstand the shock of drilling & perforating.
To keep the wellbore intact.
PRIMARY CEMENTATION JOB• The cementing takes place soon after the lowering
of casing is called primary cementation.
Conductor
Surface
Intermediate/Isolation
Production
High Press Gas
Fresh Water
Gas
Oil
Water
Oil
Surface Casing
Intermediate Casing
Production Casing
Conductor Casing
PRIMARY CEMENTING
•SECONDARY CEMENTATION JOB
- Any cementing operation that occur
after the primary cementing operation.
•PLUG CEMENTING
•Abandoned, deviation, lost zone
•SQUEEZE CEMENTING
•Seal micro annulus, water shutoff
Cement slurry design.
Quality assurance of cement and cement
additives for procurement.
Evaluation & testing of oil well cement for
procurement.
To design & formulate suitable cement
slurries for better cement bond.
To provide the best & most suitable
cement slurry design & formulation in
minimum possible time
Manufacturing of Portland Cement
• Portland cement’s basic raw material: limestone
and clay.
• Oxides of Ca, Al, Fe, Si react at high temperatures
in the Kiln (1450– 1500 ⁰C ).
• When it cools, it becomes balls of cement clinker.
• After aging in the storage, the seasoned clinker is
taken to the grinding mills where gypsum is added
to (CaSO4.2H2O) to retard setting time and
increase ultimate strength.
Cement is thought to be made up of four crystalline
components in the clinker that hydrate to form a rigid
structure.
1. Tricalcium silicate (3
CaO.SiO2 or C3S)
2. Dicalcium silicate (2
CaO.SiO2 or C2S)3. Tricalcium Aluminate (3
CaO.Al2O3 or C3A)
4. Tetracalcium aluminoferrite
(4CaO.Al2O3.Fe2O3C4AF)
The reaction is exothermic and generates a
At present the cement classes G can be
modified easily through the use of additives to
meet almost any job specifications economically.
Types of cement additives: Accelerators
Retarders
Extenders
Dispersant
Fluid loss additives
Anti-gas migration additives
Special materials:- Antifoam, silica, suspending,
weighting.
Accelerators
Used for shallow, low temp. & pressure
well.
Shortens setting time & promote early
strength development.
1. NaCl ( 3-10% BWOW )
2. CaCl2 ( 2-4% BWOC )
Retarders delay the hydration of cement to
provide sufficient time to pump slurry in the
well.
Increase thickening time but also delay
strength development.
Needed when
-Long pumping times are required.
-Temperatures are high.
Brand
Name
Manufacture
r
Effective Temp.
Range
Property
HR-4 Halliburton Up to 76 ºC Solid brown powder -Calcium
Lignosulphonate derived from
wood.
HR-5 Halliburton 52 ºC to 97 ºC Black, solid powder -chemically
modified lignosulphonate.
HR-12 Halliburton 104ºC to
171ºC
Yellowish-brown powder -is a
mixture of HR-4 retarder and an
organic acid.
D-800 Dowell 52 ºC to 121
ºC
Dark brown powder -
Lignosulphonate retarder with
reduced tendency for gelation.
D-150 Dowell 104 ºC -149
ºC
Dark Brown liquid
R-8 B.J.Service
s
93ºC to 204ºC Brown Powder
R-3 B.J.Service
s
Up to 115ºC Light brown powder,
lignosulphonate derived from the
Also called friction reducers, these
materials make cement slurries easier to
mix and pump by making them less
viscous.
Act on surface charges of the cement
grains.
Secondary retardation
Enhances fluid loss control.
Polyanions- polymelamine,
polynapthalene, polystyrene
sulpfonates ( polymers having
Brand
Name
Manufacturer Effective Temp.
Range
Property
CFR-3 Halliburton ----- Red-brown solid.
DO-65 Dowell Up to 121 ºC Light brown powder.
D-145A Dowell Up to 85 ºC Colorless, Viscous liquid low
temp. dispersant
CD-31
& CD-32
B.J.Services 4ºC to 204ºC Light brown Water soluble
polymer powder.
CD-33 B.J.Services 4ºC to 204ºC Red-Water soluble polymer
powder.
Reduces the rate at which filtrate is lost to
a permeable formation.
Works by viscosifying the mix water or by
plugging the pore throat in the filtrate cake
with long polymer chains.
Examples:
Organic polymers (Cellulose) – CMHEC,
HEC
Poly( ethyleneimine )
Polyallylamine
Brand
Name
Manufacture
r
Effective
Temp. Range
Property
Halad-9 Halliburton 15.5 ºC to
149ºC
Solid Powder- Additive is a blend
of a cellulose derivative and a
dispersant.
Halad-447 Halliburton ---- Solid, white powder -additive
containing polyvinyl alcohol.
should not be used with borax or
boric acid.
Halad-413 Halliburton Up to 204º C Solid, brown/black powder
D-167 Dowell 10ºC to
260ºC
White Solid Powder- universal &
cost-effective solution for fluid-
loss control for all cementing
application.
DO-60 Dowell Up to 120 ºC Blend of medium molecular
weight polymers
FL-19 B.J.Service
s
Up to 93ºC Water soluble high molecular
weight polymers.
Gas migration control additives are used to reduce the risk of gas invading the cement and migrating into the wellbore.
D-600 GD-700 GFLAG-56BA-10SBA-58L
Additives that reduce slurry density and
increase slurry yield are called
extenders.
– Most allow the addition of extra water to
slurry
Cement may be lightened to protect
weak formations or slurry yield may be
increased to reduce cost.
Examples:
Bentonite, Sodium silicate
Pozzolans ( Diatomaceous earth, Fly
Additives that reduce slurry density and
increase slurry yield are called
extenders.
– Most allow the addition of extra water to
slurry
Cement may be lightened to protect
weak formations or slurry yield may be
increased to reduce cost.
Examples:
Bentonite, Sodium silicate
Pozzolans ( Diatomaceous earth, Fly
These are required to counter high formation pressures.
Common high density materials are:-Haematite:
Form : Red powderSpecific Gravity:-4.7-5.25 (g/cm3)
An iron ore (Fe2O3),chemically inert and requires little additional water.
BariteForm:-White powder
Specific Gravity:-4.230 (g/cm3)Barite is a barium sulfate material used
to weight drilling mud and cement slurries.
PHYSICAL PARAMETERS UNIT REQUIREMENT
MIX WATER % BY WT. OF
CEMENT
44
FREE FLUID CONTENT % BY VOL. 5.9 (MAX)
COMPRESSIVE STRENGTH AFTER 8 HRS. CURING
i) AT 38 0C, ATMOSPHERIC
PRESSURE
PSI 300 (MIN)
ii) AT 60 0C, ATMOSPHERIC
PRESSURE
PSI 1500 (MIN)
THICKENING TIME AT 520 C,5160 PSI
RAISED IN 28 MINUTES
MINUTES 90 (MIN)
120 (MAX)
MAXIMUM CONSISTENCY ( 15 TO
30 MIN. STIRRING PERIOD)
Bc 30
Chemical Requirements
1. Magnesium oxide ( MgO), % by mass 6.0 (max.)
2. Sulphur trioxide (SO3), % by mass 3.0 (max.)
3. Loss on ignition, % by mass 3.0 (max.)
4. Insoluble residue, % by mass 0.75 (max.)
5. Tricalcium Silicate, % 65.0 (max.)
48.0 (min.)
6. Tricalcium Aluminate, % 3.0 (max.)
7. Tricalcium Aluminoferrite + twice Tricalcium Aluminate, % 24.0 (max.)
8. Total Alkali content expressed as Sodium oxide equivalent,
%
0.75 (max.)
A. Factors influencing slurry design
1. Well depth, diameter & casing size.
2. BHCT, BHST, BHP, Mud density.
3. Sample of cement, cement additive,
mixing water.
slurry design is carried out under well
simulated conditions with cementing
materials to be used at site.
B. Cement Slurry Parameters.
Density – well control & security.
Thickening Time – sufficient pumping
time.
Rheology – n’, k’, critical velocity.
Fluid Loss Control – viscosity, lost
circulation.
Free Water – channeling, settling.
Compressive Strength – WOC
All these parameter should be taken care
to maintain well security & integrity.
Mixing Devices The mixing device for
preparation of wellcement slurries shall beapprox. 1 Ltr. The twospeed mixer should becapable of 4000 RPM +200 RPM under slowspeed and capable of12000 RPM + 500 RPMunder high speed.
Screening The sample of cement to
be tested shall bepassed through 850micron (Sieve No. 20BSS).
Constant Speed Mixer
SIGNIFICANCE
Density of cement slurry is adjusted to:
Balance the formation pressure.
Control the loss of slurry in weak zones.
Facilitate the effective mud removal/displacement.
Normally, slurry density is kept higher than the mudfor facilitating the displacement of drilling fluid fromannulus. The density difference of 0.2 to 0.5 gm/cc isnormally recommended between mud and cementslurry.
Sp. Gr. can be adjusted byvarying water - cement ratio
The min. water requiredAmount to keep the initial
consistency less than 30 Bc
Max. water requiredWater separation of slurry
be kept less than 1.4%.
TEST PROCEDUREThe method for measuring thedensity of cement slurry is by useof a pressurized fluid balance.
Pressurized Fluid
Balance
SIGNIFICANCE
The thickening time is the time elapsed from the initial
application of temperature and pressure to the time required
for the slurry to reach a consistency of 100 Bc.
Thickening time is a function of temperature / pressure, typeof cement used and various additives dosed.
Thickening time of the slurry must be established forrealistic conditions to ensure adequate pumping time forslurry placement.
Thickening time is determined at BHCT conditions.
Thickening time of the cement slurry should be sufficientwhich should enable the operator to place the slurry to thepredetermined depth safely. Some margin of safety is alsoincluded so as to cover the time of break down whilecementing.
EQUIPMENTThe apparatus used is High Pressure High Temperature (HPHT) Consistometer.
HPHT CONSISTOMETER
It consist of rotating cylindrical slurry container equipped with a
stationary paddle, all enclosed in a pressure vessel capable of
withstanding well simulation pressure and temperatures.
TEST PROCEDURE•The filled slurry container is placed in the pressure vessel, then the head assembly of the pressure vessel is closed.•During the test period the temperature and pressure of the cement slurry in the slurry cup is increased in accordance with the well simulation test schedule.
SIGNIFICANCE
When cement slurry is placed against permeableformation, then water from the cement slurry enters intothe formation. This phenomenon is known as “Fluid Loss”or water loss of cement slurry. If this is not controlledseveral serious consequences may occur which lead tocement job failure or poor cementation job.As the volume of the aqueous phase decreases, theslurry density increases, as a result the performance of thecement slurry (viz. rheology, thickening time etc.) maydiverge from the original design.If sufficient fluid is lost to the formation, the slurrybecomes unpumpable, causes premature prehydration ofslurry which can lead to annulus plugging, incompletedisplacement.Cement filtrate can damage production zones.
Tests at temperature less than or equal to
88 0C• Conditioning: Atmospheric/ Pressurized
Consistometer/Stirred Fluid Loss Cell
• F/L determination: Any F/L Cell
Tests at temperature greater than 88 0C• Conditioning: Pressurized Consistometer/Stirred
Fluid Loss Cell
• F/L determination: Any F/L Cell
Atmospheric Consistometer HTHP Filter Press
SIGNIFICANCE: Different flow patterns may be encountered depending on conduit geometry,
flow velocity and physical properties of fluid.
They are characterized by the velocity and movement of the particles in different cross sections of the conduit and accordingly defined as plug flow, laminar flow or turbulent flow.
Rheology of cement slurry is defined by Bingham-Plastic or Power Law Model or Herschel-Bulkley Model of flow mechanics, which is governed by:
• Mud displacement in the annulus
• Frictional pressure drop in annulus
• Hydraulic horse power required to place the cement.
It also depends on the casing size and hole size including washouts. Slurry is designed for turbulent flow (wells with low annular clearance) or plug flow (wells with high annular clearance).
The Fann viscometer isused for calculating therheological properties ofcement slurry. Theviscometer is directindicating instrumentpowered by a motor witha gear box.
Slurry with low criticalvelocity is desired tofacilitate the cementingoperation and result ingood cementation.Fann VG
Meter
The Fann viscometer is used for
calculating the rheological properties of
cement slurry. The viscometer is direct
indicating instrument powered by a motor
with a gear box.
Slurry with low critical velocity is desired to
facilitate the cementing operation and
result in good cementation.
SIGNIFICANCE The strength developed by cement dependson various factors such as water cement ratio,temperature, time and additives used. For testingpurpose it is necessary to define all theseconditions.
The minimum compressive strength requiredto hold the casing and to seal the formation is 500psi. Compressive strength of set cements massincreases with time and temperature.
API recommends a maximum pressure of3000 psi, probably because higher pressures arehaving very little effect on compressive strengthduring hydration process.
The slurry is first preparedand then poured intomoulds in an evenlydistributed pattern andpuddling is done using aglass rod to minimizesegregation.
The moulds are nowplaced in a curingchamber and the desiredtemperature and pressureis applied. The specimensare then removed andallowed to cool.HPHT Curing
Chamber
The specimen is thentested in acompressive loadingmachine where load isapplied on the blocks.The load at whichmaterial failure takesis noted and knowingthe cross sectionalarea of that specimen,the compressivestrength of that blockcan be determined.
Compressive Strength Testing Machine
SIGNIFICANCE
The cement slurry is conditioned to simulate dynamic placement in awell bore. Slurry is left static to determine if free fluid separates fromthe slurry.It indicates the quantity of fluid separated from the cement slurry intwo hours under static conditions and expressed in percentage of theslurry volume.In case the water separation of cement slurry is very high it can formwater pockets in the annulus leading to the formation of micro channelsin the set cement.Fluid loss reducing agents generally reduce water separation ofcement slurries.The maximum permissible limits of water separation is 1.4%
DETERMINATION OF FREE FLUID SEPARATION
Slurry is prepared as per API recommended Procedure.
Poured immediately into slurry container of a HPHT
consistometer and conditioned as per thickening time test
schedule.
After conditioning, if the tempeature is higher it is cooled to 880
C, pressure released and poured into a graduated cylinder (size
between 232 & 250 mm/ length & dia ratio: 6:1 to 8:1).
The supernatant fluid developed after standing quiescent for 2
hours at 880 C is removed by decantation and measured.
Tube can be kept vertically or in tilted manner.
Free water is measured in ml as free water and is expressed as
% slurry volume.
The technology of slurry design has advanced
so much that the cementing compositions can
be tailored to any well needs.
The following major factors have been found
important which need careful consideration in
the designing of cement slurry
•Maximum available downhole density to
prevent fracturing.
•Thickening time to provide adequate pumping
and placement time with the safety margin.
Fluid loss control to prevent formation of annular rings against permeable zones and loss of hydrostatic pressure with consequent fluid migration problems.
Rheological control to facilitate pumping of cement slurry and control of displacement mechanism.
Compatibility with all other fluids in the borehole (mud, preflush, spacer etc.).
Strength, soundness strength retrogression and permeability.