Gas leakage through cement in the annular space around a cemented casing is still a serious problem although new additives and improved techniques have reduced the problem. A new approach is the construction of an emulsion cement, consisting of a double emulsion; water-in-oil-in-cement. Waterdroplets containing a controlled number of species are emulsified into mineral oil. This W/O emulsion is then emulsified into the cement slurry in small amounts (3-15 vol %). The effect of the emulsion on the cement slurry has been recorded through standard API tests. In addition the bond between cement and steel surfaces and the tightness against gas migration have been checked. Compared to other cement slurries, the emulsion cement shows promising results with respect to becoming a friction reducer and an anti gas migration additive. Further tests are necessary to determine the applicability of emulsion cement. Cement slurries behave different at high temperatures, and test procedures and test equipment must be improved in order to comply with down hole conditions.

Keywords:
migration test, slurry, migration, strength, gas migration, drilling fluids and materials, water phase, droplet, emulsion cement, reduction
Subjects:
Drilling Fluids and Materials, Casing and Cementing, Drilling fluid selection and formulation (chemistry, properties), Cement formulation (chemistry, properties)
Copyright 1991, Society of Petroleum Engineers
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