After primary and secondary production of oil from a petroleum reservoir, more than half of the oil is often left in place. In order to improve the process displacement efficiency – so that one can recover some of this remaining capillary-trapped or water-by-passed oil –, it is necessary to apply enhanced oil recovery (EOR) techniques such as surfactant flooding, either Surfactant (S), Surfactant-Polymer (SP) or Alkaline-Surfactant-Polymer (ASP).
This paper describes a complete workflow for optimizing S, SP or ASP processes for chemical EOR. The workflow consists in successive steps: reservoir fluid and rock characterizations, formulation screening, core flood validation and simulation including sensitivity studies.
Formulation design is performed through a validated High Throughput Screening (HTS) methodology using a robotic platform combined with microfluidic tools. Objective of the formulation platform is to provide a robust formulation adapted to the variability of the reservoir conditions (temperature and salinity windows, oil composition). Data on brine compatibility, oil solubilization ratio and water-oil interfacial tension (IFT) are systematically provided. Adsorption measurements are conducted for the selection of the best formulations. Core flood experiments are performed to validate performances of selected chemical formulation(s) and define simulation input data. IFT measurements, adsorption data, capillary desaturation curves, and diphasic water-oil relative permeabilities are further used as input for simulations. A chemical EOR simulator (SaripCH software), specifically designed for ASP processes design, has been developed. After the lab study, pilot design is the next step towards the application of the S, SP or ASP process in the field. SaripCH simulator is used to evaluate the performances of the process at the reservoir scale.