Cementing of fragile-formation wells with foamed cement slurries

Substantial regions of hydrocarbon production in California consist of formations that are very fragile and therefore impose a density limit on the cementitious system used to cement the well pipe. Also, troublesome fallback problems have been experienced for years in these areas. Fallback can possibly reduce production by causing formation damage. Usually the use of foamed cement offers a lowdensity cementitious material that develops adequate compressive strength while avoiding fallback problems that are due to density. In addition to reduced density, after hardening foamed cement will usually provide the advantages of temperature stability and heat insulation properties. In this paper the properties of foam cements are discussed along with the summaries of over 60 cementing jobs completed with foam cement.