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Tuesday, May 29, 2018

ASP Flooding - Reservoir Selection Criteria

A] Formation / Rock Mineralogy Sandstone Reservoirs are preferred and "Anionic Surfactant" can be used. In Carbonate Reservoirs, "Anionic Surfactant" are highly absorbed, hence cannot be used. On the other hand, "Cationic Surfactant", which might be used in Carbonate reservoirs are expensive and economically not viable. Moreover, there is also a rock of Anhydrite formation in such reservoirs. Clay also absorbs surfactant. If the reservoir has high clay contents, it might not be suitable for ASP flooding. 

B] Oil Composition and Acid Number/Acidity These are important specially for alkali & surfactant. The Acid Number of Crude should be high (min. 0.3mg KOH/g of oil or higher) so that Alkali reacts with it and produce enough soap. 

C] Oil Viscosity This is particularly important for polymer component of the flooding. It determines the required Mobility Control and hence the design Polymer concentration, slug size etc. Usually crude oil of lower viscosity of 35cP or less is preferred. 

D] The Reservoir Temperature is expected to be less than 90 C, and preferably between 40-50C. Higher temperature degrades polymer and impacts the optimal salinity of surfactant.

E] Formation Permeability is expected to be high from 500mD to Darcies for easy movement of high molecular weight chemicals, especially polymers.

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