Screening and analytical methods are often used for fast preliminary evaluations of various EOR scenarios. Screening is typically performed using real field experience and knowledge data bases, which summarize application of EOR methods to similar fields. Analytical methods are limited by simplified representation of the reservoir and EOR processes; however solutions are exact and not affected by the numerical dispersion. Often an analytical solution is used to verify numerical results. The advantages of analytical methods are in their speed and relatively small amount of data necessary to estimate the recovery of a certain EOR technique. The approach is viable and practical when a large number of reservoirs are to be screened for EOR applicability or when a decision over a new asset with limited field data is to be made.

A three-level approach to selection of EOR strategies is suggested. First the screening model allows for a fast first-order screening of key EOR applicability methods at given reservoir conditions. The applicability assessment is based on ranges for critical reservoir parameters, using a multi-criterion model and distribution functions. Than the model for oil recovery factor estimation based on the statistical data from projects carried out world wide is applied. Finally, analytical methods could be used for quantitative analysis and production profile calculations for main oil recovery methods: Depletion, Waterflooding, Cyclic Waterflooding, Polymer, Surfactant and Polymer/Surfactant flooding, Immiscible and Miscible Gas (CO2, N2, HC) flooding, Steamflooding and Immiscible WAG injection.

A wide range of reservoir parameters and computed results enable the user to perform rapid and comprehensive reservoir analyses as well as sensitivity studies. A unique feature of the developed program is its capability to handle a series of scenarios in only one single run. This tool can be compared with a “compass” helping reservoir and petroleum engineers to identify and successfully implement EOR/IOR methods at their fields.

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