amirhossein saeedi dehaghani

Research Subject:

 In recent years, smart water flooding has gained attention regarding enhanced oil recovery, and one of its driving mechanisms is wettability alteration. However, the effect of acid presence on smart water performance needs to be clarified. Thus, the main question is whether the presence of acid and potential determining ions can lead to further wettability alteration and interfacial tension (IFT) reduction. Additionally, in this study, trivalent cations were added to smart water for the first time, and the results were compared with those of divalent cations. 

Research approach: 

In this study, seawater (SW), 4-times diluted SW, and 8-times diluted SW were prepared in distilled water, 0.001 normal HCl and 0.01 normal HCl, and the contact angle and IFT experiments were carried out. In addition, concentrations of Ca2+, Mg2+, and Fe3+ were adjusted in 8-times diluted SW prepared in 0.01 normal HCl, and the IFT and contact angle tests were conducted.

The results showed that the presence of acid in distilled water could decrease the IFT values; however, it did have a marginal effect on contact angle reduction. Also, because of synergistic effects between acid and potential determining ions, IFT significantly declined. While adding acid to brines with different salinities resulted in contact angle reduction, the glass surface remained oil-wet. Regarding divalent and trivalent cations, the results revealed that increasing Fe3+ concentration in smart water made the glass surface water-wet. However, adjusting Ca2+ and Mg2+ concentrations changed the wettability from oil-wet to neutral-wet. Moreover, divalent and trivalent cations showed similar behavior in IFT reduction, and a four-times increase in the concentration of each mentioned ion reduced IFT by about 2 mN/m.

In this research, the influence and comparison of ultrasonic and microwaves on the wettability of carbonate rock have been investigated. Wettability is one of the most fundamental parameters of the oil reservoir, according to which the fluid movement in the porous medium can be examined. The aged thin sections were placed in a microwave oven and an ultrasonic bath and they were exposed to radiation for 2-10 minutes. Using the contact angle analysis, it was observed that the angle between the rock and oil drop of microwaved and ultrasonicated samples changed by 57 and 71 degrees, respectively. Contact angle and temperature changes started faster for the ultrasonicated samples. The surface charge of the rocks was determined by zeta potential analysis, and it was found that in both samples, in the first minutes of radiation, negatively charged colloids were liberated from the samples by absorbing the waves, which reduced the surface negative charges, and with the continued radiation, positively charged colloids were decreased due to the evaporation of light oil compounds. The reduction of zeta potential occurred faster for the ultrasonicated sample, but the rate of decrease was lower. By examining Fourier-transform infrared spectroscopy (FTIR) results, it was concluded that the heavy compounds on the surface of the samples were cracked and turned into lighter hydrocarbons, and the changes for both samples were almost equal. Also, the polar compounds, sulfur, and nitrogen in samples increased, decreased, and decreased respectively for both samples, and these changes were more for the ultrasonicated samples.

In this study, the effect of silica nanoparticles on the stability of foams that are stabilized with sodium dodecyl sulfate anionic surfactant was investigated. This surfactant can significantly increase the stability of the foam by reducing the surface tension. For experiments, first, the stability of the foam obtained from this surfactant in the presence of deionized water and then in the presence of NaCl solution and seawater were investigated. Then, by changing the salinity of NaCl solution and seawater, a change in the stability of the resulting foams was investigated, and the results were reported. The effect of the simultaneous presence of different concentrations of silica nanoparticles in the above solutions was investigated, and stability results were reported. According to the experimental results, the amount of foaming and the half-life of foam in the presence of deionized water is equal to 201 minutes, but the addition of brine reduces this amount. The presence of nanoparticles increases stability. In the presence of deionized water and surfactant, it reaches more than 280 minutes. Finally, the surface tension changes in the optimal concentration of the surfactant in exchange for the change in the concentration of nanoparticles were investigated. In the optimal concentration of surfactant and NaCl solution, the surface tension decreased to 21 mN/m.

This research aims to investigate the effect of microwaves on the physical and chemical properties of heavy crude oil in the presence of different minerals. In this regard, the physical and chemical changes of the oil and rock powder (sand and carbonate) mixture are investigated by microwave radiation. Viscosity and temperature changes of two samples are measured. IP143 and elemental analysis (carbon, hydrogen, nitrogen, and sulfur) are used to extract and identify the composition changes of asphaltene. The viscosity and temperature changes show that for both samples at the beginning of microwave radiation, there is a decrease in viscosity due to heavy hydrocarbon particle cracking, such as asphaltene, and converting them into lighter ones. Light compounds evaporate by continuing the radiation and temperature increase; finally, the viscosity increases. The evaporation process in the carbonate powder sample starts earlier than in the sand powder. From elemental analysis, it is concluded that the sulfur and nitrogen in asphaltene decrease almost the same for both samples, and this decrease is more evident for sulfur; thus, the rock powder combined with oil does not have a significant effect on the reduction of these elements. The increase in IFT is also observed due to the evaporation of light oil compounds, and IFT increases further due to the higher temperature of the sample containing carbonate rock powder.

The purpose of this study is to calculate Total Organic Carbon (TOC) values of the Iranian field using a combination of sonic and resistivity logs (Passay method) and neural networks method in the conditions, where the core analysis or well-log measurement does not exist. We compared the resultant TOC with the ones obtained from the geochemical analysis. To correlate between the total organic carbon data and petrophysical log, which are available after logging, Multilayer Perceptron Artificial Neural Network is used. After analyzing 100 cutting samples by using rock -Eval pyrolysis, geochemical parameters have achieved.By using the multi-layer perceptron with Levenberg–Marquardt training algorithm, the TOC with correlation coefficient 0.88 and MSE 1.443 have been provided in the intervals without analyzed samples. Finally, the TOC was estimated by using separation of resistivity and the sonic log, although, with the favorable results in some other fields, the estimation had a correlation coefficient of 51% in this field. Comparing the performance of the multi-layer perceptron with Levenberg–Marquardt training algorithm (with an accuracy of 88%) and results of the Passay method (with an accuracy of 51%) indicated that the neural network is more accurate and has better consistency compared with the empirical formula.

Using a sulfonated polyacrylamide (SPAM) and Cr3+, a new colloidal dispersion gel (CDG) was prepared. The viscosity of the CDG samples in different crosslinker concentrations and brine compositions was measured. The results showed that CDGs approach a Newtonian-like behavior in high crosslinker concentrations and salinities, signifying that they possess more rigid, less flexible particles that can be used to block some of the pore throats of the high-permeability layers. Therefore, three core flood tests were performed and the retention of the polymers and the final RRF values (residual resistance factor) were determined. Although CDGs showed a lower tendency to be adsorbed onto the rocks, they caused drastically higher RRF values (caused higher permeability reductions). Thus, it can be concluded that CDGs are superior compared to normal polymer solutions in modifying the permeability. Moreover, changing the post-flood fluid from brine to distilled water caused the RRF to decrease, hence a weaker effect on the permeability.

It is well known that asphaltene molecules play a significant role in stabilizing the emulsion of water and oil. Molecular dynamics simulation was employed to investigate the aggregation and orientation behaviors of asphaltene molecules in a vacuum, toluene, and water interface. It was found that the simulation results have a good agreement with available data. In order to investigate the effect of asphaltene structures on the self-assembled behavior of them, six different types of asphaltene structures are selected which are different in the terms of molecular weight, carbon-chain size, and heteroatoms in the asphaltene structure. At first, the behavior of asphaltene molecules was studied purely and it was found that the hydrogen bond plays a significant role in asphaltene molecule aggregation. In addition, the interfacial tension results show that the presence of OH and NH groups, as well as hetero atoms in the asphaltene molecules, cause they have hydrogen bonding with water molecules, so the interfacial tension compare to the pure toluene reduces. But on the other hand, if the asphaltene molecules do not have any O and N atoms, they have little tendency to be present at the water surface and they were dispersed inside the toluene solvent.

Prediction of gas reservoir performance in some industrial cases requires costly and time-consuming simulation runs and a strong CPU must be involved in the simulation procedure. Many reservoir parameters conform to a strong aquifer behavior on gas reservoir performance. Effects of parameters, including reservoir permeability, aquifer permeability, initial reservoir pressure, brine water salinity, gas zone thickness, water zone thickness, temperature, tubing diameter, reservoir inclination, the effective intruding angle of the aquifer, and porosity were investigated using Tornado chart, and seven parameters were filtered. Response functions of aquifer productivity index, gas recovery factor, initial maximum gas production, water sweep efficiency, gas production rate, water breakthrough time, and water production were defined statistically, using Eclipse E100 and Box-Behnken design (BBD). According to the formulae generated by the BBD based on simulation runs, reservoir permeability, aquifer permeability, well-head pressure, and gas zone thickness are the most influencing parameters on the gas reservoir performance supported by the strong aquifer. The aquifer was found to be important especially due to its productivity index and sweep water efficiency. Validation of results given by the BBD through simulation runs showed response functions of aquifer productivity index, sweep water efficiency, maximum gas production, and recovery factor are of deviation percentages in the ranges of 10.61%, 6.302%, 3.958%, and 2.04%, respectively.

Acid fracturing is one of the most widely used methods in the reservoir stimulation process for higher oil production. This method in carbonate reservoirs has a crucial role in enhanced oil recovery. Acid fracturing in fractured carbonate reservoirs changes fracture opening due to the reaction between the injected acid and minerals at the surface of fracture walls. In addition, fracture opening changes affect oil movement and the amount of oil production. In this type of reservoir, parameters such as reservoir temperature, acid injection flow rate, and injection acid type are parameters that directly affect the reaction rate between acid and carbonate rock. In this study, acetic acid was injected into two types of carbonate rock, and the effect of the rock type and acid injection rate on the final fracture opening was investigated. The results showed that dolomite rocks due to their specific nature of minerals in their structure had little reactivity with acid, thus fracture opening had lower value in comparison with the calcite rock sample. Finally, by decreasing the acid injection rate, the final fracture opening was increased after the acid injection because of more reaction between acid and fracture surfaces.

The application of membranes in various industries is one of the most urgent needs to reduce energy consumption and environmental pollutants as well as low investment costs in the process of separation. In this investigation, the optimization of effective parameters for separation of gas mixture of CH4, CO2, O2 and N2 is studied by modified poly(4-methyl-1-pentane) (PMP) membrane including nanoparticles (TiO2, ZnO, Al2O3). Design expert software was used and prevailing data on membrane modeling were categorized according to the process variables such as permeability, selectivity, composition and percentage of nanoparticle, and gas pressure difference. In order to validate the model, the results predicted by the model were compared with the experimental data. Good agreement was observed between the predicted and experimental data, and it was found that nanoparticles have a considerable effect on the results. In the case of gas permeability, the best results were obtained for the nanoparticles of alumina (15 wt%) at the pressure of 3 bar. However, titanium dioxide nanoparticle (10 wt%) at the pressure of 9 bar showed the best results for gas selectivity. The optimum point for both permeability and selectivity was obtained for the membrane containing 10 wt% titanium dioxide at 5 bar.

Water injection especially low-salinity water injection has provided a low-cost EOR method for more oil recovery. In recent years, most of the studies on low-salinity waterflooding have been focused on the investigation of the effect of water injection on rock/oil/water interaction. The purpose of this study is to investigate the fluid/fluid interaction which has received less attention in comparison with the rock/fluids interaction. In this experimental work, a series of bottle tests have been performed with 20 percent of crude oil and 80 percent of saline water (for five different common salts in the seawater) with different salinities from 6,000 to 40,000 ppm. By sampling the emulsified portion at the oil/water interface, the size distribution of the water droplets in oil has been obtained. Moreover, the size of water droplets have varied from 0.02 to 1.65 mm, and relative frequency of categories was 0.73 at its maximum. The size of water droplets decreases with a decease in the salinity. Among the salts, calcium chloride is more effective in comparison with others as the water droplet size is the lowest among three other salts, and consequently it could attract more natural surface active materials from oil to water-oil interface. The sorting of salts from highest to lowest stable emulsion is calcium chloride, magnesium chloride, sodium sulfate and sodium chloride. Ultimately, this is due to the interactions of ions in saline water with oil, charge density of ions and their surface activity.

This study is an attempt to investigate the mechanical behavior of proppant packs deforming under compression loading. A generalized confined compression test (CCT) was simulated in the present study to investigate the deformation of walnut/ceramic proppants against compression. In this way, the CCT was simulated using ABAQUS explicit code. Unlike ordinary CCT, we obtained permeability of compressed packs through image processing of deformed packs. It was observed that a pack with small particles could markedly withstand deformation, however, at the expense of having lower permeability. Also, selecting a proper proppant pack strongly depends on the prevailing stress regime, where at low stress (<30 MPa) uniform walnut pack has the same permeability as a medley of walnut/ceramic pack. But, at greater stresses (> 40 Mpa), the pack with more ceramic is the best choice. Mixtures of walnut and ceramic proppants showed greatly strength improvement compared to similar cases with pure walnut granules. As a result, making use of such packing is highly recommended due to significant mechanical stability and also being of lower price compared to packs of pure ceramic granules.

It is essential to understand gas condensate reservoir behaviour correctly. A special way of meeting this requirement is taking the advantage of well testing analysis. The simultaneous presence of condensate and gas in a reservoir alters the gas relative permeability around a production well, which influences the well test responses. Moreover, another parameter which alters this behavior more is non-Darcy flow of fluid around the well. Furthermore, some factors like the rate of production and type of gas condensate reservoirs play a crucial role in condensate formation. These factors have important impacts on the formation of condensate. In other words, they add an additional skin factor caused by the formation of condensation around wells. The aim of this study is to consider the correlation between production rate and skin factor. Moreover, the method is using data obtained from a compositional reservoir model to investigate the transient behavior around the producing well and reinterpreting the results of the reservoir model during well test analysis. Finally, in this way, by creating different scenarios of production and build-up tests, the effects of downward and upward trends of the production rate on the condensate formation and its effect on the well-test data have been examined by us. Some weight functions for representing the production rate changes versus skin factor are developed as well.

Rotational drilling was a revolution in drilling technology. It made the drilling process more efficient and faster and more depth of well could be achieved through rotation method. Besides all of its advantages, the rotation approach induced some problems like pipe sticking and downhole cleaning to the drilling procedure. Hole cleaning and reduction of torque and drag seems to be vital in inclined and horizontal ones due to its complexity and inclination. In this manuscript, hydraulic, torque and drag analysis were surveyed to investigate whether the path proposed for a well in the south of Iran is adequate or not. The required information was provided from associated drilling company and the proposed well trajectory used with hydraulic and drag data to run simulations via drilling office software. Effective axial load, Interaction of well and drill string, Comparison of stresses and von Mises graph were reported. Mentioned graphs showed the consistency of drilling project. The sensitivity of pressure drop to the pump flow rate and critical required rate to clean up annulus also reported pressure drop through the drilling system and required flow rate to clean up the bottom hole. In another word, obtained results of drag and hydraulic showed the consistency of trajectory.

A considerable quantity of the world’s oil reserve is located in naturally fractured carbonate reservoirs, with very low oil recovery efficiency, due to their wettability abd tightness of matrix. Recovery efficiency can be improved considerably, if the reservoir rock wettability is changed from mostly oil-wet to water-wet, thus enhancing water imbibition into the oil saturated rock. Smart water is able to alter the carbonate rock wetability from oil-wet to intermediate to water-wet, and therefor, water imbibition into the rock matrix is facilitated. In this study, the effect of ions and different surfactants concentration in the smart water on the wettability state of carbonate rocks was investigated by contact angle measurements and spontaneous imbibition experiments. Imbibition experiments were performed at three temperature level(50, 70 and 90 C). The effect of ions, temperature, and surfactant concentration on the wettability alteration of carbonate rocks during spontaneous imbibition process were invistegated. The results showed that the presence of SO42- ions, the strongly affects the wetting state of carbonate rocks, and increasing SO42- concentration from 0.033 mol/l to 0.1 mol/l increased the oil recovery from 19% to 58%. Moreover, by increasing Mg2 concentration the oil recovery increases (from 19% to 23%). Also the presense of cationic surfactant C12TAB, strongly changed the wetting state of carbonate rocks, and also increased the oil recovery from 19% to 78%.

Fracture reservoirs contain most of the oil reserves of the Middle East. Such reservoirs are poorly understood and recovery from fractured reservoirs is typically lower than those from conventional reservoirs. Many efforts have been made to enhance the recovery and production potential of these reservoirs. Fractured reservoirs with high matrix porosity and low matrix permeability need a secondary or EOR technique to achieve the maximum production. One of the effective EOR approaches is surfactant flooding, which reduces interfacial tension and alters wettability. Due to the complexity and uncertainty associated with such reservoirs, implementing a simulation and numerical analysis is primarily necessary to evaluate the effect of key engineering parameters on ultimate reservoir performance. This study assesses and provides a good insight into surfactant injection into fractured reservoirs using ECLIPSE software as a numerical simulator. The influences of fracture-matrix permeability ratio, initial water saturation, and the number of grids on reservoir performance were assessed and a sensitivity analysis was carried out. This study takes surfactant-related phenomena such as adsorption, surface tension reduction, and wettability alteration into account. The simulation results demonstrate that fracture-matrix permeability ratio is an important screening quantity for the selection of surfactant flooding as an EOR agent and that uncertainty in the initial water saturation of matrix has a great influence on the simulation outputs.

One of the most important issues in EOR is asphaltene deposition. Asphaltene is partly dissolved in oil, partly in steric-colloidal form and partly in micellar form depending on the composition of crude oil. Adding dispersing agents to oil, which are functionally similar to natural resin, prevents the aggregation of asphaltenes in crude oil. Inhibition strength is a capability of the inhibitor to delay formation of asphaltene flocculates, which depends on the interaction between the inhibitor and asphaltene particles. In this study, the onset of asphaltene precipitation was evaluated using a viscometric method in the presence of three types of inhibitors. In order to determine stabilization (dispersion) strength, the context of “effective adsorption point” of inhibitor is introduced by the use of the shear effects of asphaltene aggregates. The results showed that the inhibitor was adsorbed on asphaltene micelles and the stabilization strength increased with increasing inhibitor concentration. The comparison between colloidal instability index (CII) and the stabilization strength of the inhibitor indicated that the inhibition and stabilization strengths of the studied inhibitors were much higher than the natural resins.

The organic deposition particularly asphaltenes has many detrimental effects on the oil industries, such as plugging in pipelines, wellbore and facilities and subsequently, considerable reduction in well productivity.Asphaltenes are the most polar fractions, which they have been dispersed as colloidal clusters in crude oil. The accumulation of these clusters lead to the flocculation of colloids, and accordingly, formation of precipitation. Adding inhibitor is one of the ways to prevent clustering of asphaltene precipitation in crude oil. In this study, the effect of inhibitors to prevent asphaltene precipitation was investigated by viscometric method. At first, the different concentrations (1000 ppm, 2000 ppm, 10000 ppm and 20000 ppm) of some aromatic, anionic and nonionic inhibitors were prepared in a dead crude oil sample, and then the inhibition strength of samples was measured. The results showed that inhibition strength of inhibitors in low to moderate (1000 ppm – 10000 ppm) concentrations has a regular pattern, and it is associated with functional groups in chemical structure of inhibitors.

Quantity of resin that exists in raw oil is an effective parameter in asphalteneprecipitation in raw oil. Causes in formation of precipitation in reservoirs are pressure variation, temperature and formation of asphaltene and resin. As till now quantity of resin did not account. For the first time, we consider resin - asphaltene association in raw oil. Association equation of state is one of the most applicable models used for these studies. In association fluid theory, it is assumed that compressibility consists of physical compressibility factor and chemical compressibility factor. For physical part we used Peng - Robinson equation of state that added to chemical part derived in this study. By using the fact that asphaltene and resin do not affect on vapor phase, also considering asphaltene and resin precipitations as being liquid that they are acceptableassumptions, at first vapor - liquid equilibrium calculations then and liquid - liquid equilibriumcalculation performed. By calculation of asphaltene precipitation from modeling and compare them with experimental values, precipitation of resin precipitated with asphaltene can be used.