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Evaluating Reservoir Fluids Geochemistry for Planning of Surfactant-Polymer Flooding
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, IOR 2019 – 20th European Symposium on Improved Oil Recovery, Apr 2019, Volume 2019, p.1 - 17
Abstract
Geochemistry of oils and fluids is often explored for understanding of basin origin and oil migration. Variability of fluids properties is also important for IOR\EOR projects, because critical parameters of chemical flooding, such as interfacial tension (IFT) and surfactant adsorption depend upon crude oil properties and brine composition. Understanding of geochemical and geological heterogeneity became even more important for project upscaling when large blocks or an entire field are proposed for chemical flooding.
This paper presents results of lab experiments with crude oils collected from several West Siberian oilfields which are considered as potential objects for surfactant-polymer (SP) flooding.
At first, paper describes which parameters are important for SP flooding compare to ASP. It is shown that SP technology requires the different set of parameters to be taken into account. For example, optimal salinity depends upon oil EACN, salinity of formation fluids, their hardness and, sometimes, balance between Ca\ Mg as the main hardness ions. Majority of mentioned parameters is routinely measured during waterflooding, but quality of data is sometimes questionable. Therefore interpretation could be a challenging task. Approaches for prudent interpretation are discussed, need for special sampling program is justified.
Variation of oils0027; EACN was investigated inside several oilfields. Standard geochemical parameters for oil composition (SARA) are also analyzed. Significant variation of oil parameters within several fields was discovered, especially in case of coproduction from different layers. Variation of optimal salinity for SP mixture as a function of fluids hardness was investigated in a lab. Changes in IFT around optimum were measured, possible correlations are proposed.
Finally, authors discuss how to use estimated variations in EACN, salinity and hardness for high-level modeling of chemical flooding. Regional and infield variations of oil properties were converted to a range of IFT values for a specific SP cocktail. Results allow further optimization of surfactant blends and reveal most important factors influencing efficiency of SP flooding and current technical strategy.