Adewale Folayan I will leave you some details here based on what i know and for the rest i wish you will get furthermore details from others researcher and knowledgeable people.
The improved recovery methods(IOR) and enhance oil recovery methods(EOR)
Improved recovery methods(IOR): Are used to recovery additional oil/gas from the reservoir furthermore from the primary recovery.Application of further advanced technology on the field that cover all primary and secondary methods. The methods also include different types production technology as; additional vertical well,directional well,horizontal, multilateral, well stimulation and artificial lift.Usually, the recovery methods as following: (fluid expansion, rock compressibility, gravitational drainage and natural water flow or gas drive)
Enhance Oil Recovery: is defined as increasing the oil that can be extracted from the reservoir by applying ( miscible displacement, Chemical injection, thermal methods).
IOR includes a wide variety of production technologies like (infill drilling) or complex well designs (deviated, or slanted, wells; horizontal, or single-lateral, wells; multi-lateral wells), well stimulation (hydraulic fracturing and acidizing), artificial lift (beam pumps, ESPs, and gas lift), secondary recovery methods (waterflooding and gas flooding), But EOR processes includes (thermal recovery, miscible displacement, and chemical flooding).