Carbon sequestration is the action of capturing CO2 emissions and pumping them deep into the ground where they will stay for years and years and years, preventing them from contributing to Global Warming.
CO2 intensive industries, especially coal power plants, are depending upon this technology to help keep them profitable in the face of CO2 emissions restrictions.
The coal industry is fighting for its profitability with a marketing campaign, rebranding themselves "Clean Coal".
The question becomes is Carbon Sequestration a good solution to acomplish the goal of reducing CO2 emissions.
So lets presume it works succesfully.
Carbon plus Oxygen plus Oxygen equals CO2 and into the ground it goes.
Evidence from prehistoric times indicates that the oxygen content of pristine nature was above the 21% of total volume that it is today. It has decreased in recent times due mainly to the burning of coal in the middle of the last century. Currently the oxygen content of the Earth's atmosphere dips to 19% over impacted areas, and it is down to 12 to 17% over the major cities. At these levels it is difficult for people to get sufficient oxygen to maintain bodily health: it takes a proper intake of oxygen to keep body cells and organs, and the entire immune system, functioning at full efficiency. At the levels we have reached today cancers and other degenerative diseases are likely to develop. And at 6 to 7% life can no longer be sustained.
I am not convinced that burying oxygen in the ground is a good idea.
I think it is a better idea to leave the carbon in the ground and the oxygen in the air.