Halliburton Co. is denying that unstable drilling cement foam triggered the April 20 deadly explosion at the Macondo well, although the Houston-based oil-field services company admits it did not test the final cement mixture for stability before using it. On Oct. 28, Fred Bartlit Jr., the lead investigator for the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, issued a report on Oct. 28 stating the cement foam was unstable and may have contributed to last spring’s blowout. Bartlit reported that tests performed by Chevron Corp. on a cement-slurry, or drilling mud, mixture— similar to that
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.