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Collaborating Authors
Results
Simulation Study of Effects of Surfactant Properties on Surfactant Enhanced Oil Recovery in Fractured Reservoirs
Cheng, Xiaoqian (Norwegian University of Science and Technology) | Kleppe, Jon (Norwegian University of Science and Technology) | Torsæter, Ole (Norwegian University of Science and Technology(NTNU), PoreLab - Porous Media Laboratory, NTNU and University of Oslo)
Abstract Surfactant addition could improve oil recovery of water flooding in mixed-wet/oil-wet naturally fractured reservoirs by changing wettability or reducing water/oil interfacial tension (IFT). But the mechanisms of surfactant enhanced oil recovery (EOR) in fractured reseroirs are not fully understood. One objective of this work is to analyze the effects of surfactant properties (viscosity, concentration, and adsorption) on surfactant EOR at laboratory scale. The other objective is to obtain the functional relationships between surfactant properties and oil recovery of surfactant flooding. A core with length of 8 cm and diameter of 4 cm is cut into two parts from the middle to imitate the matrix with a horizontal fracture whose space is 0.1 cm. The middle slide with a width of 0.1 cm is used as the model in this study. Fluid is injected from left side of the fractured and produced from the right side. The original properties of matrix, brine, and oil are from Ekofisk Field. The properties of surfactant are assumed based on literatures. Eclipse is used as the simulator. The viscosity of surfactant solution has no obvious effect on ultimate oil recovery. But the time to obtain ultimate oil recovery, which is called the ultimate oil recovery time in this paper, is linearly increasing with the increase of viscosity. Since most of surfactants have no significant effect on viscosity of brine, the viscosity of surfactant solution is not a key parameter of surfactant screening for surfactant EOR in fractured reservoirs. The increase of surfactant concentration results in a decrease of oil recovery rate, and an increase of ultimate oil recovery. The ultimate oil recovery at 364 days of surfactant flooding has a negative linear relationship with inverse square root of surfactant concentration. The surfactant concentration has a more significant effect on oil recovery from lower matrix than the oil recovery from upper matrix. The ratio (RC) of the maximum mass of adsorbed surfactant to the mass of surfactant at critical micelle concentration (CMC) is used to describe the effect of surfactant adsorption on oil recovery. Two cases are studied and results imply that the surfactant capability of wettability alteration should be considered first for surfactant screening. If surfactants have the same capability of wettability alteration, then the surfactant adsorption is a key parameter, and the smaller surfactant adsorption concentration leads to a larger ultimate oil recovery. This work helps to understand the mechanism of surfactant flooding in fractured reservoirs, and could be used as a reference for surfactant screening for surfactant EOR in fractured reservoirs. The functional relationships between surfactant properties and oil recovery help to improve upscaling methods.
- Asia (0.68)
- North America > United States > Texas (0.29)
- Europe > Norway > North Sea > Central North Sea (0.24)
- Materials > Chemicals > Specialty Chemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Tor Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Ekofisk Formation (0.99)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Fahud Salt Basin > Yibal Field > Yibal Khuff Formation (0.99)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Fahud Salt Basin > Yibal Field > Sudair Formation (0.99)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Abstract The effect of geochemical reactions and the kinetics of minerals are not completely understood in reactive-transport problems such as low-salinity waterflooding (LSF) or alkaline/surfactant/polymer (ASP) injection method. These processes do not only act as an inert displacement and geochemistry also plays a major role in the fluid behavior and oil recovery. In this paper, first, the importance of the kinetics of minerals with fast and slow rate kinetic reactions (e.g., calcite and quartz, respectively) in different conditions during reactive-transport floods is investigated using PHREEQC geochemical package. Then, two-phase Buckley-Leverett (BL) flow is coupled with IPhreeqc which is open-source module of the PHREEQC geochemical package in order to study the effect of the geochemical reactions and the kinetics of minerals on the oil recovery in two different displacement distances. This coupling provides a simple tool for modeling the geochemical reactions to understand the effect of the geochemistry on the two-phase and 1D flow, and consequently the oil recovery. Finally, as an example, the significance of the kinetics of minerals in LSF and in oil recovery is studied at two different scales. The results show that temperature, in-situ water composition and buffering capacity have a great impact on the kinetics of mineral. It has been shown that minerals with slow rate kinetic reaction (e.g., quartz) might be excluded in reactive-transport phenomena at core-scales. However, minerals with fast rate kinetic reactions (e.g., calcite) must be included when modeling lab results. On the other hand, the residence time at field-scales is large enough for the mineral dissolution and precipitation to affect the local equilibrium constants. Therefore, in modeling field-scale applications, local equilibrium assumption (LEA) can be applied for fast rate kinetic minerals, whereas kinetics should be used for slow rate kinetic minerals (e.g., quartz).
- Europe (0.28)
- North America > United States (0.28)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Mineral > Silicate > Tectosilicate > Quartz (0.67)
- Geology > Mineral > Carbonate Mineral > Calcite (0.57)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Statfjord Group (0.98)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Lunde Formation (0.98)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/4 > Snorre Field > Statfjord Group (0.98)
- (9 more...)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)