Secondary production injects water into the reservoir to displace and produce additional oil not recovered during primary production. This stage produces an additional 10 percent to 20 percent of the oil in the reservoir.
During secondary recovery, injecting water into the reservoir under pressure to moves the oil. This process is called waterflooding and acts more efficiently and economically because water displaces oil better than gas.
However, eventually secondary recovery methods also reach its economic limit leaving approximately two-thirds of the original oil in the reservoir. This unrecovered oil amounts to 300 billion barrels nationally; and 10 billion comes from the State of Kansas, making it necessary to use another method of recovery.