Api Cement And Additives

API Cement and Additives Cementing I Course Jakarta, January 2011 For Internal Use Only

AGENDA 1. Functions of the Primary Cementing Process

2. API Cement 3. Cement Properties

4. Cement Additives

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Primary Cementing The principal functions of the primary cementing process :    

Bond and support the casing Restrict fluid movement between formations Protect the casing from corrosion Protect the casing from shock loads when drilling deeper  Seal off lost circulation (or thief) zones

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Cement History      

Gypsum Cement – 3000 BC Limestone Cement – 800 BC Portland Cement – 1824 First Steel Casing Cemented – 1903 First Cement Job by Halliburton – 1919 Class G Cement – 1964

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Portland Cement Composition  Limestone (or other materials high in calcium carbonate)  Clay or shale  Some iron and aluminum oxides (if not found in quantity in the clay or shale).

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API Cement Classification  API Class A and B (Portland cement)  API Class C (High early strength cement)  API Class D, E and F (Retarded cement)  API Class G and H (Basic cement)  API Class J (Special order only).

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API Classification And Properties Of Common Oil Well Cements

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API Class-G Cement Properties Slurry Weight : 15.8 ppg Slurry Yield : 1.15 cuft/sk Water Requirement : 5.0 gal/sk Free Water : 5.9% Compressive Strength 8 hrs, 14.7 Psi, 100 degF : 300 Psi 8 hrs, 14.7 Psi, 140 degF : 1500 Psi Thickening Time @ 125 degF : 90 – 120 min

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Cement Properties The properties of cement slurry are influenced by factors such as:    

Water ratio of cement slurries (gal/sk) Slurry density (lb/gal) Slurry yield (ft³/sk) Additives

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Cement Properties  Thickening Time  Rheology Properties  Free Water  Settling  Fluid Loss  Compressive Strength

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Cement Additives Accelerator Cement accelerators shorten thickening time and reduce WOC. They also increase early strength

The common accelerators are :      

Calcium Chloride (most widely used) Sodium Chloride Seawater Cal-Seal ECONOLITE VersaSet

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Cement Additives Cement Retarder Additives Cement retarders slow cement setting time (hydration) to allow for safe cement placement

The common Cement Retarder Additives are :  Lignins (sodium lignosulfonate, calcium lignosulfonate)  Carboxymethyl hydroxyethyl cellulose (CMHEC)  Saturated salt water  Organic acids  Synthetic polymers For Internal Use Only

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Cement Additives Light Weight Additives A slurry weight needs to be reduced to protect formations that have a low fracture gradient or for economics

The common Light Weight Additives are :    

Bentonite Spherelite Water Foam Cement

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Cement Additives Heavy Weight Additives The main purpose of heavy weight additives is to restrain high formation pressures

The common Heavy Weight Additives are :     

Barite Micromax Hematite Sand Salt

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Cement Additives Lost Circulation Additives “Lost circulation” or “lost returns” refers to whole fluid loss or cement slurry loss to formation voids during drilling or completing a well

The common Lost Circulation Additives are :    

Granular (gilsonite, coal, perlite, walnut hulls, mica) Fibrous (nylon, polypropylene) Laminated (cellophane) Specialized flash setting or gelling material

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Cement Additives Fluid Loss Additives Fluid loss additives counteract the tendency of cement slurries to lose the water that the slurries need to help achieve a good cement job

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Cement Additives Cement Dispersants or Friction Reducers Dispersing agents are added to cement slurries to improve their flow properties.

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Cement Additives Gas Control Additives The time period of gelation, before cement sets may be several hours. In this state the unset slurry will not fully transmit fluid pressure from wellbore fluids

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Cement Additives Silica Strength Stabilizing Agent is used to stabilize the strength and permeability of cement where temperatures are higher than 230°F. It is effective in preventing strength retrogression and decreasing permeability in cement systems.

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Cement Additives Spacer 1. Mud Flush 2. Super Flush 3. Dual Spacer 4. Tuned Spacer

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Thank You For Internal Use Only