Kent Wells of BP said on August 6 during the briefing that BP pumped just a little over 500 barrels of cement down the casing. He added “I think it was roughly about 200 barrels into the formation and the rest remained in the casing”. BP plans to remove failed Blowout Preventer after well is killed on August 15 – 20, and install a formal plug during regulatory abandonment procedure.

Source: http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/incident_response/STAGING/local_assets/downloads_pdfs/BP_technical_audio_08062010.pdf