2) Cementing Additives

Introduction to Cementing Additives

Well Conditions Mud Removal Friction Pressure Mixability Pumpability

Permeable formations

Well Control Over Pressure Weak Formations

Temperature Heat Retrogression

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Lost Circulation Foamers

Foam

Well Conditions

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PROBLEM

SLURRY PARAMETER

WELL CONTROL OVER PRESSURE WEAK FORMATION

DENSITY

TEMPERATURE

THICKENINGTIME

PERMEABLE FORMATIONS

FLUIDSTABILITY FLUIDLOSS CONTROL

MUDREMOVAL FRICTION PRESSURE MIXABILITY/PUMPABILITY

RHEOLOGY

ADDITIVE CATEGORY SOLUTIONS EXTENTERS WEIGHTINGAGENTS ACCELERATORS RETARDERS FLAC DISPERSANTS GELLINGAGENTS

LOST CIRCULATION

PLUGGING BRIDGINGPROPERTIES DENSITY

EXTENTERS

HEAT RETROGRESSION

HYDRATION PRODUCT

Silica

FOAMERS

STABILIZEDFOAM CAPABILITY

FOAMINGAGENTS AND STABILIZERS

FOAM

FOAMINGTENDENCY

ANTI-FOAM

LCM

Cementing Additives • Accelerators and Retarders

• Dispersants

– Change thickening time

– Improve mud removal

– Alter rate of compressive strength development

– Improve mixability

• Extenders – Reduce slurry density – Increase slurry yield

• Weighting Agents – Increase slurry density

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– Reduced water slurries – Reduce friction pressure (Low Ty and Pv)

• Fluid Loss Control • Lost Circulation Material (LCM)

Speciality Additives • • • • •

Antifoam/ defoamer agents Bonding agents Expansive additives Gas migration control additives, etc. Thixotropic systems

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Antifoam Agents • What cause foam? – Properties of materials – Poor wetting of solid particles

• Why use antifoam agents? – Prevent slurry gelation/ prevent poor hydration – Prevent pump cavitation – Allow true slurry density to be mixed and pumped

• Properties of antifoam – Insoluble in the foaming fluid – Have more surface active than foaming fluid

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Antifoam Agents • Mechanism of action – Spread on foam surface with lower surface tenstion – Enter foam reducing film and causing rupture

• Types of antifoam agents – Polyglycol ethers Solid: D046 (0.20 lb/sk) Liquid: D047 (0.05 - 0.07 gal/sk) – Silocones Liquid: D175 (0.01 - 0.05 gal/sk) Liquid: M045 (0.05 gal/sk) Liquid: D144, obsolete-replaced by D175

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Conductor pipe • Prevents washing out under rig • Short rig downtime • Quick setting cement -rapid development of compressive strength • Accelerated slurries, e.g. – Neat Cement+NaCl (D44) 3-5% – Neat Cement+CaCl2 (S1) 2-4% – Neat Cement+Sea Water

• Cemented with Stab-in or just driven

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Accelerators • Shorten stage I and II, accelerate stages III and IV hydration of main cement phases is increased plus change in C-S-H structure • Offset retarding effects of other additives I

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II

III

IV

V

Accelerators • S001 (CaCl2-solid)

1 - 4 % BWOC

– Check purity: S001 = 77% CaCl2 purity – Exothermic reaction

• D044 (NaCl)