TY - THES

T1 - Alkali-based Displacement Processes in Microfluidic Experiments: Advanced Statistical Analyses

AU - Kharrat, Ahmad

N1 - no embargoed

PY - 2018

Y1 - 2018

N2 - Since oil production declines over time, waterflooding and Enhanced Oil Recovery (EOR) are applied to increase the recovery, at the secondary and tertiary stages of production. Waterflooding is used for pressure maintenance and oil displacement, while the injection of chemically modified water may lead to a higher recovery in the tertiary stage of production. Water-based EOR methods, such as alkaline, surfactant and/or polymer flooding are commonly used due to their efficiency and low cost. Especially attractive is alkaline flooding, in which oil displacement is enhanced through interfacial tension (IFT) reduction, microemulsion generation and wettability alteration. In this thesis, alkaline flooding was investigated by using microfluidics (2D porous media etched in glass) providing (a) a well-defined chemical environment and (b) displacements can be studied with high spatial and time resolutions. Hence, microfluidics allows studying chemical EOR processes in great detail. In the frame of the present study, several experiments have been performed with different water compositions varying the alkalinity and salinity of the injection water. All the experiments were performed with crude oil of target field from Vienna basin, which has a high viscosity and TAN number. The flooding experiments have been performed in different porous media, representing high and low permeability and capillarity systems. The purpose of this work was to enhance the experimental workflow in order to eliminate earlier observed inconsistencies. In this frame, it turned out that conventional measurements like the oil production from the porous medium (recovery) are not a good measurement, because the flooding domain does not represent an elementary volume for multi-phase flow. Therefore, discrete frequency distribution and Lorenz plot analyses were applied to characterize the efficiency of water flooding and EOR process by acquiring quantities of data for comparing the results and understanding complex displacements. Based on the obtained results, the synthetic water performed like an alkali agent and displaced a significant amount of oil compared to the pure-water flood. Upon statistical analyses, it has been observed that oil cluster size was reduced in alkaline flooding, which can be used as a fingerprint that distinguishes this process from water flooding. However, the link and connection between statistical analyses with ultimate recovery were not achieved and still requires further investigation.

AB - Since oil production declines over time, waterflooding and Enhanced Oil Recovery (EOR) are applied to increase the recovery, at the secondary and tertiary stages of production. Waterflooding is used for pressure maintenance and oil displacement, while the injection of chemically modified water may lead to a higher recovery in the tertiary stage of production. Water-based EOR methods, such as alkaline, surfactant and/or polymer flooding are commonly used due to their efficiency and low cost. Especially attractive is alkaline flooding, in which oil displacement is enhanced through interfacial tension (IFT) reduction, microemulsion generation and wettability alteration. In this thesis, alkaline flooding was investigated by using microfluidics (2D porous media etched in glass) providing (a) a well-defined chemical environment and (b) displacements can be studied with high spatial and time resolutions. Hence, microfluidics allows studying chemical EOR processes in great detail. In the frame of the present study, several experiments have been performed with different water compositions varying the alkalinity and salinity of the injection water. All the experiments were performed with crude oil of target field from Vienna basin, which has a high viscosity and TAN number. The flooding experiments have been performed in different porous media, representing high and low permeability and capillarity systems. The purpose of this work was to enhance the experimental workflow in order to eliminate earlier observed inconsistencies. In this frame, it turned out that conventional measurements like the oil production from the porous medium (recovery) are not a good measurement, because the flooding domain does not represent an elementary volume for multi-phase flow. Therefore, discrete frequency distribution and Lorenz plot analyses were applied to characterize the efficiency of water flooding and EOR process by acquiring quantities of data for comparing the results and understanding complex displacements. Based on the obtained results, the synthetic water performed like an alkali agent and displaced a significant amount of oil compared to the pure-water flood. Upon statistical analyses, it has been observed that oil cluster size was reduced in alkaline flooding, which can be used as a fingerprint that distinguishes this process from water flooding. However, the link and connection between statistical analyses with ultimate recovery were not achieved and still requires further investigation.

KW - Alkaline flooding

KW - Micromodel

KW - EOR

KW - Statistical analysis

KW - Enhanced oil recovery

KW - Alkalische Flutung

KW - Mikromodelle

KW - EOR

KW - Statistische Analyse

KW - Enhanced oil recovery

M3 - Master's Thesis

ER -