Green Oil & Gas

Oil & Gas production through present drilling technologies is expensive and damaging to the environment, huge reserves of oil exist in blocked and marginal oil wells but current methods of recovering it make little sense, either in economic or environmental terms.
Green Oil and Green Gas is much related to the various Enhanced Recovery methods using steam injection, chemical flooding, and CO2 injection (which is widely used).

Tar sands in particular hold decades worth of black oil but all current extraction processes scar the landscape and are so expensive that there is no margin for environmental restoration.

Enhanced Oil Recovery (CO2 injection)

A typical oilfield recovery is 30-40% of the original oil in place (OOIP), so almost two-thirds of the OOIP is currently considered "unrecoverable" with conventional technologies.
CO2 is often "miscible" with the reservoir oils, which means it is more effective in scrubbing oil out of the rocks than is a substance like water which is "immiscible" with oil.
If you get grease on your hands and wash them with plain water, an immiscible fluid, you find that it is not an effective cleaning agent, however, if you wash with "soap" or something else that is miscible with the oil, you get nice clean hands. This is similar to the effect achieved by miscible CO2 flooding in an oil reservoir. Some basic calculations will tell the pressure at which your oil is likely to "miscible".

A successful miscible CO2 flood may recover 8-15% OOIP over and above the recovery from a conventional oilfield operation, bringing the total oilfield recovery to 40-50% OOIP. While recovery from a successful immiscible CO2 flood will be lower albeit with lower costs.

Enhanced Gas Recovery (CO2 injection)

Normally, a natural gasfield is produced by simply reducing the reservoir pressure, much like deflating a football, with a "typical" recovery of 60-80% of the original gas in place (OGIP).
However, it is possible to inject CO2 or other waste gases back into a conventional gasfield, this process will increase the reservoir pressure (re-inflating the football) and push the remaining valuable natural gas towards the production wells. This "enhanced gas recovery" or EGR process could recover a significant amount of additional natural gas (say, 10-20% OGIP) while sequestering a substantial amount of CO2.

Coalbed methane (cbm) is another rapidly growing source of natural gas production. Cbm production is slightly different than in conventional gas reservoirs, in that the natural gas (methane) is "stuck" to the microscopic coal surfaces, and only when pressure is reduced does it come off the coal and flow to the wells. However, CO2 has properties that make it stick to the coal surfaces even more tightly than does methane, so CO2 injection into coalbed methane reservoirs (ECBM) can also increase natural gas recovery while simultaneously sequestering large volumes of CO2.

Enhanced Recovery (CO2 injection)

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