Market Research
Enhanced Oil Recovery (EOR) refers to the recovery of oil that is left behind after primary and secondary recovery methods are either exhausted or no longer economical. Before proceeding with a discussion of EOR, it is important to have a basic understanding of primary and secondary recovery.
Primary production is the first oil out, the easy oil. Once a well has been drilled and completed in a hydrocarbonbearing zone, the natural pressures at that depth will cause the oil to flow through the rock or sand formation toward the lower pressure wellbore, where it is lifted to the surface. While primary recovery is the least expensive method of extraction, since it uses natural forces to move the oil, it typically recovers only 10% to 15% of the Original Oil in Place (OOIP).
Secondary recovery methods are used when there is insufficient underground pressure to move the remaining oil. The most common technique, water flooding, utilizes injector wells to introduce large volumes of water under pressure into the hydrocarbon bearing zone. As the water flows through the formation toward the producing wellbore, it sweeps some of the oil it encounters along with it. Upon reaching the surface, the oil is separated out for shale and the water is reinjected. While somewhat more expensive than primary production, water flooding can recover an additional 10% to 30% of OOIP.
When water flooding for secondary recovery reaches a point when production is no longer cost effective, a decision must be made whether to transition the field to a tertiary recovery phase. An EOR program utilizing Surfactant Polymer (SP) flooding may be indicated, depending on the characteristics of the formation being produced and the economics involved. The chemical components of the SP process, used alone or in combination are mixed with water which is injected into the formation as in a traditional water flood. Surfactant cleans the oil off the rock much like dish soap cuts the grease in a frying pan; Polymer spreads the flow through more of the rock.