We truly declare that this submitted work, entitled "Evaluation of Natural Surfactant Potential in Carbonate Reservoir", is a product of our original research work to the best of our knowledge. One of the main drawbacks of enhanced oil recovery (CEOR) is the reduction of excessive chemical usage. The effect of temperature on the rheological properties of the natural surfactant solution was measured in the range 25-55 °C.
This study presented the potential of extracted natural surfactant for the use of CEOR as a cheap and more accessible alternative to traditionally used surfactants.
LIST OF APPENDICES
Chapter One
Introduction to the study 1.1. Introduction
- Problem Statement
- Study Scope
- Significance of the Study
- Chapter Organization
The importance of the study was also described from four aspects: economic, technical, environmental and social. Based on the available literature, it investigates the general effect of concentration, temperature, salinity, pH, adsorption and oil type aspects on the result of surfactant application. In addition, the performance of oil with natural surfactants was studied based on the results of oil recovery in core flooding.
Furthermore, varying salinity accounts for different IFT, permeability, and oil recovery measurement results for distilled water and seawater solutions.
Chapter Two Literature Review
Enhanced Oil Recovery (EOR)
This is achieved by increasing the apparent viscosity of the fluid or reducing the effective permeability of the rocks. A significant increase in water viscosity can be achieved by adding high molecular weight water-soluble polymers (Sheng, 2011). In addition, the injection of surfactants results in a decrease in residual saturation and thus an increase in relative permeability, resulting in higher oil sweep efficiency (Sheng, 2015).
At best, an effective and successful chemical candidate should improve oil recovery.
Surfactant
- Factors affecting surfactant performance
- Concentration
- Temperature
- Salinity
- Adsorption
- Oil type
At a concentration of the surfactant below the CMC value, a significant adsorption increase is observed due to surface aggregation. In contrast, the values above CMC, increasing concentration does not affect the adsorption behavior of the surfactant (Belhaj et al., 2019). Usually, the reservoirs undergo the water flooding process during a certain period before the application of CEOR, and the injected water salinity can be close to the value of the salinity of the reservoir water itself (Ramesh and Sakthishobana, 2021).
The salinity of the injected water should be approximately equal to the optimum salinity; this is the value at which the lowest IFT is observed. In contrast, the increase in salinity can also lead to the reduction of the repulsive forces between the surface of the rock and surfactant molecules (Belhaj et al., 2019; Kumar and Mandal, 2019). As with varying pH, the charge of the surfaces of the solid also changes, and the adsorption of the surfactant depends on this parameter.
With an increase in the pH value of the surfactant solution, the number of hydroxyl groups decreases, which affects hydrogen bonding. It occurs due to van der Waals and electrostatic interactions between the surface of the solid and the surfactant itself. This parameter is one of the most vital aspects and can negatively affect the effectiveness of the application of CEOR.
As a result of this reduction to this certain limit and thus the economic optimization of the method, the oil displacement efficiency can be successfully improved (Sheng, 2011). The API weight of the oil is less important than its viscosity, considering these parameters as potential screening criteria (Sheng, 2015).
Application of natural surfactants
All surfactants were found to be compatible with brine and the most effective performance of natural surfactants was observed at a CMC value of 0.4 wt%. However, the behavior of natural surfactants was not studied under temperature and pressure reservoir conditions to ensure the high potential in enhanced oil recovery application (Obuebite et al., 2020). According to the core flooding results, the injected 5 PV of extracted surfactant increased the oil recovery factor by 28.89%.
The study was performed in the presence of hydrophilic silica nanoparticles, also called HISNPs, and although the electrical conductivity methods were performed, as well as the adsorption data collection, the adsorption process was only characterized as a result of the study. Hydrophobicity was mainly investigated in the work as well as the molecular weight identification of the natural surfactant based on the freezing point dipping method with sodium dodecyl sulfate as the reference surfactant. As a result, hydrophobicity values were found in the range of 0.116 to 0.194, which has proven the ability of IFT reduction.
Although four different plant surfactants were studied, the main focus of the study was on their hydrophobic properties, while the decrease in IFT and increase in oil recovery were only mentioned as theoretical implications and assumptions based on the study results. Adsorption tests and core flooding tests should be performed in further studies to develop the proposed hypotheses. Foam stability tests and static adsorption tests were performed to study the characteristics of the natural surfactant.
In this chapter, an overview of the role of chemical enhancement oil recovery in increasing production has been given. The result of the finding is that more researchers have become interested in environmentally friendly chemicals.
Chapter Three Methodology
Preparation of the surfactant solution
Chemical Characterization 1. FTIR analysis
- IFT determination
- Rheology Test
The ratio of the sample spectrum to the background spectrum represents the spectrum of the sample. The device used for IFT measurements was the IFT 700-HPHT Interfacial Tension Meter from Vinci Technologies, Nanterre, France. The mechanism is as follows: through a capillary needle, a droplet (drop liquid) is formed in the chamber containing bulk liquid.
The droplets can be captured using state-of-the-art image capture, and the system calculates the necessary geometric parameters to derive the interfacial tension using Laplace's equation. As a droplet in the experiment, we used octane synthetic oil with a red dye to separate it from the surfactant, since both liquids were transparent. Stock solutions of surfactants with DIW and seawater brine were used in bulk.
If the density of the droplet is lower than that of the bulk liquid, the capillary needle should be adjusted from below so that the droplet will rise; if not, it should be the other way around. As the motor is torqued, the internal resistance to the material flow can be measured. Base solutions have a low viscosity; thus, the measuring tool for the MCR-302 was changed to a cylindrical one, requiring 50 ml of solution for each run.
50 ml of stock solution was placed in the measuring cylinder, and the viscosity was measured at different temperatures between 25℃ and 65℃ with increments of 10℃ for each concentration. The concentrations used in this experiment are 0.5, 2 and 5 wt% of the surfactant solution with DIW.
Core Flooding
Chapter Four Results and Discussion
- Natural Material Characterization
- Fourier Transform Infrared Spectroscopy
- Surfactant Properties 1. Interfacial Tension
- Rheology
- Core Flooding
- Core Characterization
- Absolute Permeability
- Coreflooding
- Summary
Thus, the presence of saponin in the extracted surfactant was confirmed as a result of the identification of its terpenoid signature. For example, FTIR analysis of surfactant extracted from Baphia nitida seed oil has identified the presence of C-H stretching and C=C-H vibrations (Adewuyi, 2019). As these relationships were shown by the spectra of the extracted surfactant sample, the presence of saponin within the surfactant could be ascertained based on comparative analysis within the published literature.
The micelle formation results in either the head or tail group of the surfactant pointing inwards. In the current study, the IFT measurement is used as identification of the inflation point. The CMC values of the surfactant solutions with both DIW and at 35000 ppm salinity (seawater salinity) were identified as a result of the IFT measurement.
Regarding brine, an increase in salt concentration leads to the formation of micelles more easily, which reduces the CMC value (Zhang, Li, & Zhao, 2022). It allowed the stretching of the surfactant between the interfaces, which reduced the CMC and resulted in less IFT compared to the DIW case in Fig. Surfactants can also promote emulsification; these factors change the molecular structure of the solution (Nakama, 2017).
Consequently, the apparent viscosity of the solution varies with the surfactant concentration. The results are presented as a plot of cumulative oil recovery for DIW and brine in Figure 1.
Chapter Five
Conclusion and Recommendations
Future research should focus deeply on the effects of salinity and temperature on the performance of the surfactant. Wider range of the salinity and temperature values should be studied for the better sensitivity analysis. Since only the synthetic oil was used in the study, the crude oil should be used in the further experiment to test the application of the natural surfactant.
In addition, it is necessary to simulate the actual conditions in the reservoir for a more accurate analysis of the performance and effectiveness of surfactants in the Kazakh fields.
The effect of surfactant concentration, salinity, temperature and pH on adsorption of surfactants for chemical enhanced oil recovery: a review. Salinity Effect in Cloud Point Phenomena by Nonionic Surfactants Used in Enhanced Oil Recovery Tests. Experimental investigation on the effect of Vitagnus plant extract on enhanced oil recovery process using interfacial tension (IFT) reduction and wettability change.
Experimental investigation of Seidlitzia rosmarinus effect on oil-water interfacial tension: useful for chemical enhanced oil recovery. Characteristic Curve Determination of Some Natural Surfactants for Chemical Enhanced Oil Recovery Applications in Nigeria. Polymer flooding and its effect on enhanced oil recovery with special reference to Upper Assam Basin.
Introductory investigation of a polymeric surfactant from a new natural source in chemically enhanced oil recovery (CEOR). Chuback's natural surfactant solution with added xanthan gum: a green and clean technique for improved oil recovery. Influence of Fluid Rheology and Sandstone Permeability on Enhanced Oil Recovery in a Sandstone Microfluidic Device.
Integrating Surfactant, Alkali, and Nano-Fluid Flooding for Enhanced Oil Recovery: A Mechanistic Experimental Investigation of New. Experimental study of Matricaria chamomilla extract effect on oil-water interfacial tension: Application to chemically enhanced oil recovery.
Appendix A Gantt Chart
Appendix B
Permeability values of core #2 with DIW: a) absolute, b) effective and core #1 with brine: c) absolute, d) effective
