12 Principles and Applications
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of Cement Slurries D. Guillot and J. F. Baret Etudes et Productions, Schlumberger—Division BP202, 92142 Clamart Cedex, France
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The basic principles of oil well cementing are first described together with the main critical engineering constraints encountered during a primary cementing operation, that is, wellbore control, mud displacement, fluid loss control, and gas migration. Then cement slurry properties that are relevant to the process are reviewed and the procedures used to measure these properties are discussed. Particular attention is given to rheological measurements that can be affected by wall slip when using coaxial cylinder or pipe flow viscometers. This is followed by an overview of the additives that are used to obtained the required cement slurry or set cement properties, like weighting agents/extenders, retarders, dispersants, fluid loss agents, and antisettling agents. Some typical mechanisms of action of these additives are briefly discussed.
Functions
of Cementing Slurries
Introduction to Oil Well Cementing. Applications of cement slurries to oil well drilling are several. The main operation, called primary cementing, consists of placing such fluids in the annular space between the borehole and a cylindrical t u b e — t h e c a s i n g — w h i c h is used to line the borehole at several stages during drilling (Figure 1). T h e cement, once set, supports the casing and seals off the annulus. This fulfills the main objectives of the operation, that is, • isolate the w e l l bore from formation fluids • prevent migration of formation fluids in the annulus behind the casing • protect the casing against corrosion by formation fluids 0065-2393/96/0251-0601$15.75/0 © 1996 A m e r i c a n C h e m i c a l Society
In Suspensions: Fundamentals and Applications in the Petroleum Industry; Schramm, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1996.
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SUSPENSIONS: F U N D A M E N T A L S & APPLICATIONS IN P E T R O L E U M INDUSTRY
Figure 1. Primary casing cementing. (Reproduced with permission from reference 1. Copyright 1984 Dowell Schlumherger.) To supplement a faulty primary cement job, cement slurries are also circulated behind the casing between two sets of perforations at the bottom and at the top of the desired interval. This is called remedial cementing. T w o other types of operations involve cement slurries. They are used to plug back a well from a deeper to a shallower depth for a number of reasons: abandonment, whip stocking, lost circulation, or shutting off water. Squeeze cementing consists of forcing a column of cement slurry
In Suspensions: Fundamentals and Applications in the Petroleum Industry; Schramm, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1996.
12.
GUILLOT & BARET
Principles
