Papers by Shahab Ayatollahi
Applied Energy, Jun 1, 2020
Condensation process plays a critical role in the efficiency of solar stills. • Wettability of co... more Condensation process plays a critical role in the efficiency of solar stills. • Wettability of condensation surface affected the condensation mechanism. • Titanium dioxide and silicon nanoparticles were coated on the condensation surface. • Nano-coating of condensation surface changed the surface wettability. • Wettability alteration of condensing surface increased the productivity by 10-35%.
Fuel, Apr 1, 2018
Enhanced Oil Recovery (EOR) through various methodologies has been an active research for many ye... more Enhanced Oil Recovery (EOR) through various methodologies has been an active research for many years seeking efficient methods to increase the crude oil recovery efficiency from oil reservoirs. Among different gas injection scenarios, carbon dioxide (CO 2), natural gas (mainly methane (CH 4)) and nitrogen (N 2) injection are considered as promising EOR agents. Asphaltene precipitation and deposition during EOR methods cause severe problems, which affect the recovery efficiency and increase the cost of the incremental oil production. This study is aimed to investigate the effects of CH 4 and N 2 injection compared with CO 2 injection on asphaltene precipitation and deposition. The different mole percent of the mentioned gases were introduced into the highpressure cell, then the amount of precipitated asphaltene was measured at the reservoir condition. The evolution of asphaltene deposition was monitored through a high-resolution microscope. Moreover, Image processing software was utilized to check the amount of deposited asphaltene and its size distribution under different conditions. The most apparent finding to emerge from this study is that both CO 2 and natural gas increase the amount of precipitated asphaltene whereas the nitrogen as an inert gas has no considerable effect on the amount of precipitated asphaltene. According to the results, the increment of precipitated asphaltene by CO 2 is much higher than natural gas. Further, the thermodynamic solid model used in this study reasonably predicted the trend of asphaltene precipitation process for the mentioned EOR scenarios.
Fuel, 2019
Asphaltene deposition during enhanced oil recovery (EOR) processes is one of the most problematic... more Asphaltene deposition during enhanced oil recovery (EOR) processes is one of the most problematic challenges in the petroleum industry, potentially resulting in flow blockage. Our understanding of the deposition mechanism with emphasis on the rate of the asphaltene deposition is still in its infancy and must be developed through a range of experiments and modelling studies. This study aims to investigate the rate of asphaltene deposition through a visual study under different gas injection scenarios. To visualise the asphaltene deposition, a high-pressure setup was designed and constructed, which enables us to record high-quality images of the deposition process over time. Present research compares the effects of nitrogen (N2), carbon dioxide (CO2) and methane (CH4) on the rate of asphaltene deposition at different pressures. The experimental results in the absence of gas injection revealed that the rate of asphaltene deposition increases at higher pressures. The results showed that the rate of asphaltene deposition in the case of CO2 injection is 1.2 times faster than CH4 injection at 100 bar pressure. However, N2 injection has less effect on the deposition rate. Finally, it has been concluded that the injection of CO2 leads to more asphaltene deposition in comparison with CH4 and N2. Moreover, the experimental results confirmed that gas injection affects the mechanism of asphaltene flocculation and leads to the formation of bigger 2 flocculated asphaltene particles. The findings of this study can help for a better understanding of the mechanism of the asphaltene deposition during different gas-EOR processes.
SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition, 2017
Carbon dioxide miscible flooding is known as a very efficient and challenging enhanced oil recove... more Carbon dioxide miscible flooding is known as a very efficient and challenging enhanced oil recovery (EOR) method. Besides the high oil recovery efficiency, the asphaltene precipitation and deposition is believed to be triggered by a perturbation of the thermodynamic equilibrium present in the reservoir. Asphaltene deposition results in wettability alteration and plugging in the reservoir as well as affecting the production facilities. The complicated mechanism of phase separation in asphaltene-containing systems makes it crucial to study the effects of different parameters on the aggregation of asphaltene particles. In this study, a novel high-pressure visual cell equipped with a high-resolution microscope along with the image processing software was prepared to investigate the growth of asphaltene particles on a sample reservoir rock. The quantity of asphaltene deposition was determined at several pressure depletion steps and different temperatures with and without CO2 injection. T...
Special Topics & Reviews in Porous Media - An International Journal, 2011
ABSTRACT The steam-assisted gravity drainage (SAGD) process has been studied experimentally in he... more ABSTRACT The steam-assisted gravity drainage (SAGD) process has been studied experimentally in heavy oil sand-packed models using different scenarios of steam injection. In this study, cyclic and continuous steam injection were used separately and in ...
Special Topics & Reviews in Porous Media: An International Journal, 2015
The grain-size distribution (GSD) of porous rocks is important in order to better understand thei... more The grain-size distribution (GSD) of porous rocks is important in order to better understand their hydrodynamic behavior. Clear and precise GSD data can be used to computationally reconstruct rock structure for further analysis. In this study, three main algorithms for image analysis have been examined to estimate the GSD of clastic rocks. The main challenge in GSD determination from images is in detecting overlapping grains and measuring their size separately. In this study, three previously developed image processing algorithms are implemented on two-dimensional (2D) binary images of rocks in order to compare the obtained GSD from each of the methods, i.e., the mean intercept length method, erosion and dilation method, and watershed segmentation method. Grains can be visually overlapped for several geological reasons, such as severe compaction, diagenesis, or cementation. When the overlapping degree of grains is severely increased, the image processing algorithms fail to detect the true grain size. A sensitivity analysis has been done on several synthetic random packed rock samples to evaluate the field of applicability and the accuracy of the aforementioned methods via different grain overlapping degrees. Finally, a comparison between the discussed methods is presented, which helps researchers choose the appropriate algorithm that fits their rock samples.
SPE Middle East Oil and Gas Show and Conference, 2009
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 20... more Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Middle East Oil & Gas Show and Conference held in the Bahrain International Exhibition Centre, Kingdom of Bahrain, 1518 March 2009. This paper was selected for ...
Journal of Porous Media, 2008
ABSTRACT
Energy Fuels, May 24, 2010
Yibal oil reservoir, a fractured carbonate formation located in the north of Oman and characteriz... more Yibal oil reservoir, a fractured carbonate formation located in the north of Oman and characterized by high salinity brine and high temperatures, is a potential candidate for enhanced oil recovery (EOR) projects. This experimental study focused on the possibility to use surfactant injection as an EOR process in the Yiabl field. On the basis of the results from our previous investigations, ethoxylated sulfonates and amphoteric surfactants were used in this study. Selected surfactants showed a great tolerance to high salinity and temperatures. All surfactant systems displayed dynamic interfacial tension (IFT) behavior, in which transient ultra-low IFTs were detected. Dilute surfactant solutions (0.1 wt %) were considered for core-flooding tests on limestone plugs. In one set of experiments, surfactant solutions were injected into a fully water-flooded core (surfactant tertiary recovery). In another set, surfactant solutions were injected without pre-water-flooding (surfactant-modified water-flooding or surfactant secondary recovery). Results of tertiary recovery were found to be between 1 and 7% of original oil in place (OOIP), which correspond to 6 and 24% of residual oil in place (percentage based on the remaining oil in place after water-flooding). Tertiary surfactant injection therefore appears to be an attractive option for pre-water-flooded zones for additional oil recovery. In the other hand, results of secondary recovery for some surfactants showed significant oil recovery compared to water-flooding, whereas for other surfactants, water-flooding was more effective. Secondary surfactant recovery resulted in faster rate recovery as compared to water-flooding. Thus, minimum pore volume (PV) injected at ultimate oil recovery for 7-58 surfactant was found to be significantly lower (2.3 PV) than the corresponding PV in water-flooding (9.1 PV).
Http Dx Doi Org 10 1080 15567036 2011 582610, Dec 17, 2014
The main objective of this study is utilizing of recurrent neural networks (RNN) to categorize pr... more The main objective of this study is utilizing of recurrent neural networks (RNN) to categorize pressure derivative plots of well testing data into various reservoir models.
Journal of Petroleum Science and Engineering, 2016
72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, 2010
Microbial Enhanced Oil Recovery Enterobacter cloacae wettability alteration relative permeability... more Microbial Enhanced Oil Recovery Enterobacter cloacae wettability alteration relative permeability micromodel interfacial tension a b s t r a c t Microbial Enhanced Oil Recovery (MEOR) as a tertiary process employs microorganisms and their metabolites to reduce the residual oil saturation of the reservoir mainly through interfacial tension (IFT) reduction and wettability alteration. In spite of its great potential and the mentioned advantages, application of MEOR has been limited because of the lack of practical convincing experimental results. In this study, the effects of MEOR process on wettability changes and the reduction of residual oil saturation have been examined by providing microscopic visualization of two phase flow in transparent glass micromodels. Biosurfactant producing bacterial strain (Enterobacter cloacae) was utilized to investigate the impacts of both the biofilm and biosurfactant on wettability of the micromodel pore walls by measuring the relative permeabilities before and after microbial treatment. Results indicated that wettability of the pores was altered towards more water wetness which was also supported by visual observation of the oil/water phase saturations in the glass micromodel. Moreover, the oil recovery was increased up to 24.5% of the original oil in place (OOIP) during the MEOR process. At last, Biofilm formation was found to be more responsible for the wettability alteration process.
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 20... more Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Middle East Oil & Gas Show and Conference held in the Bahrain International Exhibition Centre, Kingdom of Bahrain, 1518 March 2009. This paper was selected for ...
Many oil reservoirs in the world including those in Iran have been producing oil for a long time;... more Many oil reservoirs in the world including those in Iran have been producing oil for a long time; hence, they are at the end of their natural/primary production period. Enhanced oil recovery (EOR) processes are proposed for additional oil recovery after the primary and secondary oil recovery periods. Gas injection in particular CO 2 injection is a well-established method for incremental oil recovery in the oil reservoirs. This process is also considered as an environmental friendly process for CO 2 sequestration. CO 2 gas injection encounters some shortcomings such as low sweep efficiency, early breakthrough and high risk of gas leakage. Carbonated water injection (CWI) has been recently proposed as an alternative method to resolve the problems associated with gas injection.
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2014
Fines migration is the major reason for productivity decline known as formation damage in oil res... more Fines migration is the major reason for productivity decline known as formation damage in oil reservoirs. Nanofluids are good candidates for being injected into nearby wellbore regions because of their very small sizes for remediation purposes.
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Papers by Shahab Ayatollahi