How does CO2 stay underground through sequestration?
Carbon dioxide can be sequestered in different ways. When CO2 is compressed it can be injected via deep wells into oil and gas production zones deep underground. Under layers of impermeable “cap rock,” oil and gas has been held in porous rock reservoirs for millions of years. As the oil and gas is produced, it travels through the porous rock to a well and then to the surface, essentially freeing space between the grains of rock where CO2 can be injected to replace the produced oil and gas. Another option is to pump CO2 into saline aquifers where it dissolves in salty water, just like sugar dissolves in tea. The water with CO2 dissolved in it is then heavier than the water around it (without CO2) and so it sinks to the bottom of a rock formation, trapping the CO2 indefinitely. Another form of sequestration takes place when CO2 reacts with the minerals in the surrounding rocks and forms new minerals on the rocks, much like shellfish use calcium and carbon from seawater to form their shel
