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Foamed cement has been used extensively across a variety of applications for oil and gas well cementing, including deepwater riserless cementing, low fracture gradient cementing, horizontal well cementing, steam injection well cementing, and high-pressure/high-temperature (HP/HT) cementing. When using foamed cement, laboratory testing is used to estimate the performance characteristics of foamed cement slurries that are designed for well applications. It is well known that significant differences exist between the methods used to generate foamed cement in the laboratory and those used to generate foamed cement for field applications. The implications of these differences on foamed slurry characteristics (e.g., bubble size distribution) and performance properties (e.g., stability, permeability, mechanical properties) has not been well analyzed or well understood. This paper documents a project that was undertaken through a joint effort between API Sub-Committee 10 and the National Energy Technology Laboratory (NETL) to examine the differences between foamed slurries generated with laboratory equipment and field foamed cementing equipment. Methods for generating and capturing foamed cement samples using field equipment are discussed, as well as analytical methods for evaluating the characteristics of foamed cements. References to the resulting data are provided. Finally, conclusions and recommendations are presented that were developed during the course of the project. |
