Oilfield flooding applications

When oil is discovered in an underground reservoir, the initial stage of oil recovery occurs easily due to the inherent underground pressure acting on the field from associated water or gas. This forces oil to the surface via the bore at the production well. This process is known as primary recovery. In secondary recovery environments, additional force is applied to the reservoir to aid further oil recovery This is necessary when the natural pressure drive in the reservoir has either been depleted or was never sufficient from the beginning. The process usually involves water being pumped underground via an injection well. 

in reservoirs where there is a lot of variation in permeability (referred to as heterogeneity), the tendency will be for the injection water used in the oilfield flooding operation 

Polymer composition/ionic content (high-charge density usually gives greater viscosity per unit weight of polymer due to electrostatic repulsion effects). 

Electrolyte content of injection water (high ionic strength results in significant chain coiling of highly charge polyelectrolytes. 

Typically, a polymer concentration in the range of 500-2000 mg/1 is required to achieve a viscosity of up to 100 cP at shear rates corresponding to the flow rate in reservoirs with typical permeability. As described above, flow occurs through tortuous routes or channels of the porous rock strata, and the solution is exposed to a range of forces which impact on both the shear viscosity and extensional viscosity properties of the polymer solution. 

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Application of Chemical Flood Processes in the Oilfield Hankensbiittel B. Maitin 3nd European EOR-Conference, Rome (1985)... 

Fenglan, W., Xia, L., Siyuan, L., Peihui, H., Wanting, G., and Yonghui, Y. 2010. Performance Analysis and Field Application Result of Polymer Flooding in Low-Permeability Reservoirs in Daqing Oilfield. Paper SPE 136904 presented at the Canadian Unconventional Resources and International Petroleum Conference, Calgary, 19-21 October. DPI 10.2118/136904-MS. 

Lakatos, I., Toth, J., Bodi, T Lakatos-Szabo, J., Berger, P.D., and Lee, C. 2007. Application of Viscoelastic Surfactants as Mobility-Control Agents in Low-Tension Surfactant Floods. Paper SPE 106005 presented at the International Symposium on Oilfield Chemistry, Houston, 28 February-2 March. DPI 10.2118/106005-MS. 

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