The gases produced are trace amounts of nitrogen oxides, trace amounts of sulfur oxides, significant amounts of water vapor, and the remaining portion is carbon dioxide. The nitrogen and sulfur compounds dissolve in the water condensate formed at a cooler portion of the recycling process of the CO2. The acids formed are extracted for sale as industrial feed-stocks. Using or not using the pure water product for cooling purposes affects the overall efficiency by .5 to 1 percent. About 3% excess inventory of CO2 working fluid formed from the fuel combustion would be continually tapped off at a 30 bar pressure level for pipeline transport to oil reservoirs projects. This Senate Committee report provides some additional detail.
Natural gas is CH4. The hydrogen weighs very little. The carbon combines with the pure oxygen fed in, and becomes CO2. The carbon and oxygen molecules weigh about the same as the carbon, so the resulting gas weighs three times as much as the natural gas going in. The result is not a 3 percent "excess inventory", it's 300 percent. ALL of the CO2 is excess inventory. It is never consumed in the process.