Cement filtration control

Filtration control additives are added to cement slurries for the same reason that they are added to drilling muds. However, untreated cement slurries have... 

Filtration control additives are added to cements for the same reason they are used in drilling fluids. Untreated cement slurries, however, have much greater filtration rates than do untreated drilling muds. Therefore it is very important to limit the loss of water from a slurry into a permeable formation. This is... 

However, the mechanism of action of filtration control additives is not yet completely understood. Examples are bentonite, latex, various organic polymers, and copolymers. Many additives for fluid loss are water-soluble polymers. Vinyl sulfonate fluid loss additives based on the 2-acrylamido-2-methyl-propane sulfonic acid (AMPS) monomer are in common use in field cementing operations [363]. The copolymerization of AMPS with conjugate monomers yields a fluid loss agent whose properties include minimal retardation, salt tolerance, high efficiency, thermal stability, and excellent solids support. 

A dispersant that can be used in drilling fluids, spacer fluids, cement slurries, completion fluids, and mixtures of drilling fluids and cement slurries controls the rheologic properties of and enhances the filtrate control in these fluids. The dispersant consists of polymers derived from monomeric residues, including low-molecular-weight olefins that may be sulfonated or phosphonated, unsaturated dicarboxylic acids, ethylenically unsaturated anhydrides, unsaturated aliphatic monocarboxylic acids, vinyl alcohols and diols, and sulfonated or phosphonated styrene. The sulfonic acid, phosphonic acid, and carboxylic acid groups on the polymers may be present in neutralized form as alkali metal or ammonium salts [192,193]. 

J. Kieffer, M. Michaux, and P. Rae. Additive for controlling the filtrate of well cementing slurries and corresponding cementing process (ad-ditif pour le controle du filtrat des laitiers de cimentation de puits, et procede de cimentation correspondant). Patent FR 2592056,1987. 

After placement, a static filtration process occurs, that is, the only flow is the filtration one, perpendicular to the bore hole surface, and the cake grows. If the cake is growing too much, it may bridge the annulus and prevent hydrostatic pressure to be transmitted downhole jeopardizing the control of the well (Figure 5). Finally, there are constraints that are related to the nature of the solid particles in suspension, that is, portland cement. 

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