Savonius Wind turbines are special class of Vertical Axis Wind Turbines (VAWT). These are low cost drag driven turbines and are known to be inefficient.The performance of the new design is extensively studied on OpenFOAM-v1812 , a popular open source CFD library. The flow equations coupled with equations of rotation of the turbine are solved on an overset mesh framework. This study also serves as a validation of recently released over-set support in OpenFOAM. The turbulence is incorporated by coupling Reynolds Averaged Navier Stokes (RANS) with Shear Stress Transport (SST) κ-ω eddy viscosity turbulence model. The turbulence parameters are set to produce a flow with Reynolds number, Re=4.8 × 105. To have better confidence in the simulations, this study also presents a comparison of numerical flow over conventional savonius turbine designs with published data. It is observed that a majority of CFD analysis on wind turbine designs are performed for fixed tip speed ratio on a traditional static mesh structure. But, in this CFD study, a wind driven rotation of savonius turbine is simulated on an overset dynamics approach. The results of the study are compared and discussed based on the predicted moment and power coefficients, pressure variatioon the blades, velocity flow field and wake analysis. The study indicated that the bladed design presented here has a potential to increase the power efficiency of a savonius wind turbine by 10% to 28%

This research is a continuation of efforts aimed at establishing the modified affinity laws for viscosity to predict the pump performance directly from a plot in terms of dimensionless numbers, i.e., flow coefficient, Reynolds number, head coefficient, and efficiency. The group has earlier proposed modified head coefficient affinity law. This work proposes and validates a similar efficiency plot that completes the set of modified affinity laws that include all the input and output parameters for a specific pump design and type. A wide range of viscosities and flow rates are considered for CFD analysis to have a comprehensive set of data that includes enough data points to comment on both the laminar and turbulent flow cases categorized based on the hydraulic Reynolds number (2300). Initial analysis shows some inconsistency based on laminar versus turbulent simulation model selection which is addressed in the latter part of this work. In general, two curves can be constructed for laminar and turbulent flow cases. These curves have different axes parameters (exponents of the dimensionless numbers) depending on the plot being for a laminar or a turbulent flow case. Validation with established experimental data shows good agreement in terms of the variation of axes parameters (their exponents) depending on the pump type for a single suction impeller and a double suction impeller pump. The distinction between laminar and turbulent flow cases is found to be applicable to established experimental data as well.

Chelating agent solutions have been proposed as effective fluids for enhancing oil production. Different recovery mechanisms are reported for increasing the oil recovery during chelating agent flooding. The aims of this work are to identify the possible recovery mechanisms during chelating agent flooding in carbonate reservoirs and to investigate the in situ CO 2 generation as a potential recovery mechanism during the injection of chelating agent solutions into carbonate reservoirs. The contribution of CO 2 on enhancing the oil recovery was determined using experimental measurements and analytical calculations. Several measurements were conducted to study the contribution of each mechanism on enhancing the oil recovery. Coreflooding tests, zeta potential measurements, CO 2 generation, and interfacial tension (IFT) experiments were carried out. Also, analytical models were utilized to determine the impact of the injected chemicals on reducing the capillary pressure and improving the flow conditions. In flooding tests, two chemicals (EDTA and GLDA) were injected in a sequential mode and the chemical concentration was increased gradually. In addition, a comparative study was performed to evaluate the effectiveness of EDTA and GLDA solutions to enhance oil recovery. Several parameters were investigated in this paper including incremental oil recovery, in situ CO 2 generation, hydrocarbon swelling, IFT, wettability alteration, permeability enhancement, productivity index, and chemical cost. The obtained results show that GLDA chelating agent has better performance than EDTA solutions for enhancing the oil recovery when the same concentrations are used. Also, the in situ generation of CO 2 shows a significant impact on improving the oil recovery from carbonate reservoirs during chelating agent flooding. In the literature, the reported recovery mechanisms of using chelating agents are the IFT reduction, wettability alteration, and rock dissolution. Based on this work, injecting chelating agent solutions at low pH can lead to involve additional recovery mechanisms due to the CO 2 generation, the additional mechanisms are hydrocarbon swelling, viscosity and density reduction, and oil vaporization.

T-junctions have been applied in water-control structures. A comprehensive understanding of shunt characteristics can contribute to the optimal design of T-junctions. In this work, we seek to understand the shunt ratio of fluids with different viscosities in a T-junction and to achieve a greater shunt ratio. The computational fluid dynamics (CFD) approach is applied to study the influence of the properties, such as the fluid viscosity, the branch angle, the channel shape, and the flow rate, on the shunt ratio in a T-junction. The viscosity of oil can be divided into three intervals, and the optimal angles of the T-junction are different in each interval. For the fluid viscosity in the 1–20 cP range, the optimal branch angle is in the 45–60 deg range. For the fluid viscosity in the 20–65 cP range, the branch angle should be designed to be 45 deg. For the viscosity greater than 65 cP, the branch angle should be designed to be 75 deg. The appearance of the eddy and secondary flow will reduce the flow. The secondary flow and eddy intensity on the branch increase with increasing angle. The secondary flow intensity of the main channel decreases gradually with the increase in the angle. This study provides an important guidance for the design of automatic water control valve tools.

This study was aimed to understand the rheological properties and stability characteristics of biochar-algae-water (BAW) slurry fuels prepared by wet milling. A pine sawdust biochar and a chlorella vulgaris algae were used in preparing the slurry fuels. The BAW slurries were formulated by mixing the biochar, algae, de-ionized water, lignosulfonic acid sodium salt, and then the mixture was ball-milled for various times. The BAW slurries with a constant solid loading of 45 wt % were prepared with varied algae proportion in algae/biochar mixture. The apparent viscosity and stability of BAW slurries were measured. It was found that D 50 of the particles of the solid in the slurries decreased with increasing milling time. The viscosity of the slurries decreased first and then increased as milling time increased, reaching a minimal value when D 50 of the solid was between 3 and 7 μ m. The lowest viscosity of BAW slurries achieved at a given solid loading increased with increasing the algae proportion in the solid. The BAW slurries showed better stability at higher algae proportions due to enhanced flocculation.

A new drilling method called coiled-tubing partial underbalanced drilling (CT-PUBD) was proposed in this paper. The method is not only able to enhance rate of penetration (ROP) just like the conventional underbalanced drilling technology but can also maintain borehole stability in the upper formation. In the new method, the wellbore pressure system is divided into two parts by a packer: (1) normal pressure system in the upper formation used to balance formation pressure and maintain borehole stability and (2) an underbalanced pressure system in the annulus near the bit used to enhance ROP. Because the pressure system and the circulation system are different, the cuttings transportation process of the method is different from the conventional way. Therefore, it is essential to study how to carry cuttings away efficiently. The flow field and cuttings distribution in the annulus near the bit were analyzed by computational fluid dynamic (CFD) methods. Cuttings transportation trajectory, velocity distribution, and cuttings concentration distribution were obtained under different holes’ parameters of the backflow device (including holes number, diameter, distance, and angle) and different drilling fluid viscosities. The results show that these parameters all have influence on cuttings carrying efficiency, and the most influential parameters are viscosity, angle, and diameter. According to the result of an orthogonal test, a suitable combination of the holes’ parameters was obtained. In the combination, the value of holes number, diameter, distance, and angle is 4, 50 mm, 300 mm, and 120 deg, respectively. This paper provides a theoretical basis for an optimization design of the new method.

The paper presents physicochemical properties of pyrolysis oil (PO) blends obtained from pyrolysis of rubber and spent tires mixed with selected heavy fuel oil (HFO) and the effect of PO properties on physicochemical properties of the final heavy heating oil. On the basis of physicochemical properties determinations, one sample of PO was selected, which was characterized by the best properties from the point of view of technological application. In the next step, physicochemical properties for the selected sample of heavy heating fuel oil consisting of 25% PO and 75% HFO were determined. It was found that the most important property of tire-derived PO is the content of gasoline, i.e., light hydrocarbons with a boiling point below 180 °C, which determine the ignition temperature of the obtained fuel blends. This property determines also the amount of PO that can be added to HFO, on the order of 30 wt % and more. The lower content of light hydrocarbons, the greater the amount of PO can be used to compose HFO. A positive aspect of the use of tire derive PO for the composing of heavy heating fuel is about a threefold decrease in kinematic viscosity, lowering the flow temperature and a significant reduction in ash content. Other properties of the modified HFO remained virtually unchanged and the fuel obtained as a result of blending meets the requirements of the relevant standard.

Fracturing is a fundamental technique for enhancing oil recovery of tight sandstone reservoir. The pores in tight reservoirs generally have small radii and generate tremendous capillary force; accordingly, the imbibition effect can significantly affect retention and absorption of the fracturing fluid. In this study, the imbibition behaviors of the fracturing fluid were experimentally investigated, and the effects of interfacial tension, (IFT) permeability, oil viscosity, and the salinity of the imbibition fluid were determined. In addition, combining with nuclear magnetic resonance (NMR)-based core analysis, fluid distribution, and the related variations in imbibition and displacement processes were analyzed. Finally, some key influencing factors of imbibition of the residual fracturing fluid, the difference and correlation between imbibition and displacement, as well as the contribution of imbibition to displacement were explored so as to provide optimization suggestions for guiding the application of oil-displacing fracturing fluid in exploration. Results show that imbibition recovery increased with time, but the imbibition rate gradually dropped. There exists an optimal interfacial tension that corresponds to maximum imbibition recovery. In addition, imbibition recovery increased as permeability and salinity increases and oil viscosity decreases. Furthermore, it was found that extracted oil from the movable pore throat space was almost equal to that from the irreducible pore throat space during imbibition and their contribution in the irreducible pore throat space was greater than in the movable pore throat space in the displacement process. Hence, imbibition plays a more important role during the displacement process in the reservoirs with finer porous structure than previously thought.

The rheological properties of the drilling fluid play a key role in controlling the drilling operation. Knowledge of drilling fluid rheological properties is very crucial for drilling hydraulic calculations required for hole cleaning optimization. Measuring the rheological properties during drilling sometimes is a time-consuming process. Wrong estimation of these properties may lead to many problems, such as pipe sticking, loss of circulation, and/or well control issues. The aforementioned problems increase the non-productive time and the overall cost of the drilling operations. In this paper, the frequent drilling fluid measurements (mud density, Marsh funnel viscosity (MFV), and solid percent) are used to estimate the rheological properties of bentonite spud mud. Artificial neural network (ANN) technique was combined with the self-adaptive differential evolution algorithm (SaDe) to develop an optimum ANN model for each rheological property using 1029 data points. The SaDe helped to optimize the best combination of parameters for the ANN models. For the first time, based on the developed ANN models, empirical equations are extracted for each rheological parameter. The ANN models predicted the rheological properties from the mud density, MFV, and solid percent with high accuracy (average absolute percentage error (AAPE) less than 5% and correlation coefficient higher than 95%). The developed apparent viscosity model was compared with the available models in the literature using the unseen dataset. The SaDe-ANN model outperformed the other models which overestimated the apparent viscosity of the spud drilling fluid. The developed models will help drilling engineers to predict the rheological properties every 15–20 min. This will help to optimize hole cleaning and avoid pipe sticking and loss of circulation where bentonite spud mud is used. No additional equipment or special software is required for applying the new method.

During the drilling operations, optimizing the rate of penetration (ROP) is very crucial, because it can significantly reduce the overall cost of the drilling process. ROP is defined as the speed at which the drill bit breaks the rock to deepen the hole, and it is measured in units of feet per hour or meters per hour. ROP prediction is very challenging before drilling, because it depends on many parameters that should be optimized. Several models have been developed in the literature to predict ROP. Most of the developed models used drilling parameters such as weight on bit (WOB), pumping rate (Q), and string revolutions per minute (RPM). Few researchers considered the effect of mud properties on ROP by including a small number of actual field measurements. This paper introduces a new robust model to predict the ROP using both drilling parameters (WOB, Q, ROP, torque (T), standpipe pressure (SPP), uniaxial compressive strength (UCS), and mud properties (density and viscosity) using 7000 real-time data measurements. In addition, the relative importance of drilling fluid properties, rock strength, and drilling parameters to ROP is determined. The obtained results showed that the ROP is highly affected by WOB, RPM, T, and horsepower (HP), where the coefficient of determination (T 2 ) was 0.71, 0.87, 0.70, and 0.92 for WOB, RPM, T, and HP, respectively. ROP also showed a strong function of mud fluid properties, where R 2 was 0.70 and 0.70 for plastic viscosity (PV) and mud density, respectively. No clear relationship was observed between ROP and yield point (YP) for more than 500 field data points. The new model predicts the ROP with average absolute percentage error (AAPE) of 5% and correlation coefficient (R) of 0.93. In addition, the new model outperformed three existing ROP models. The novelty in this paper is the application of the clustering technique in which the formations are clustered based on their compressive strength range to predict the ROP. Clustering yielded accurate ROP prediction compared to the field ROP.

The rheological properties of bentonite suspensions depend on the chemical composition and the contained dominant element, such as calcium (Ca), potassium (K), and sodium (Na). Na-bentonite type is the one used in drilling fluids, because it has good dispersion stability, high swelling capacity, and outstanding rheological properties. Ca-bentonite generally has bad rheological performance; however, it can be activated by sodium to be used in drilling fluids, since there are huge unutilized Ca-bentonite resources. Many previous attempts of activation of Ca-bentonite were not feasible, upgrading required addition of many extra additives or sometimes mixed with commercial Na-bentonite to improve its properties. In this paper, a process of integrated beneficiation method is designed to efficiently remove the nonclay impurities and produce pure Ca-bentonite. An upgraded Ca-bentonite was produced using a combined thermochemical treatment in a wet process by adding 4 wt % of soda ash (Na 2 CO 3 ) while heating and stirring. The new thermal treatment optimized and described in this study greatly improved the sodium activation and ions exchange process and improved bentonite properties. The thermochemically upgraded Ca-bentonite outperformed the rheological properties of the commercial bentonite. And when tested in a typical drilling fluid formulation at high temperature, the investigations showed an identical behavior of the commercial drilling grade bentonite. Moreover, the results obtained showed that the thermochemically upgraded Ca-bentonite has higher yield point/plastic viscosity (YP/PV) ratio than commercial Na-bentonite when mixed with the drilling fluid additives. Higher YP/PV ratio is expected to enhance the hole cleaning and prevent most of the drilling problems.

Diffusion coefficient of carbon dioxide (CO 2 ), a significant parameter describing the mass transfer process, exerts a profound influence on the safety of CO 2 storage in depleted reservoirs, saline aquifers, and marine ecosystems. However, experimental determination of diffusion coefficient in CO 2 -brine system is time-consuming and complex because the procedure requires sophisticated laboratory equipment and reasonable interpretation methods. To facilitate the acquisition of more accurate values, an intelligent model, termed MKSVM-GA, is developed using a hybrid technique of support vector machine (SVM), mixed kernels (MK), and genetic algorithm (GA). Confirmed by the statistical evaluation indicators, our proposed model exhibits excellent performance with high accuracy and strong robustness in a wide range of temperatures (273–473.15 K), pressures (0.1–49.3 MPa), and viscosities (0.139–1.950 mPa·s). Our results show that the proposed model is more applicable than the artificial neural network (ANN) model at this sample size, which is superior to four commonly used traditional empirical correlations. The technique presented in this study can provide a fast and precise prediction of CO 2 diffusivity in brine at reservoir conditions for the engineering design and the technical risk assessment during the process of CO 2 injection.

Determination of optimal well locations plays an important role in the efficient recovery of hydrocarbon resources. However, it is a challenging and complex task. The objective of this paper is to determine the optimal well locations in a heavy oil reservoir under production using a novel recovery process in which steam is generated, in situ, using thermochemical reactions. Self-adaptive differential evolution (SaDE) and particle swarm optimization (PSO) methods are used as the global optimizer to find the optimal configuration of wells that will yield the highest net present value (NPV). This is the first known application, where SaDE and PSO methods are used to optimize well locations in a heavy oil reservoir that is recovered by injecting steam generated in situ using thermo-chemical reactions. Comparison analysis between the two proposed optimization techniques is introduced. On the other hand, laboratory experiments were performed to confirm the heavy oil production by thermochemical means. CMG STARS simulator is utilized to simulate reservoir models with different well configurations. The experimental results showed that thermochemicals, such as ammonium chloride along with sodium nitrate, can be used to generate in situ thermal energy, which efficiently reduces heavy-oil viscosity. Comparison of results is made between the NPV achieved by the well configuration proposed by the SaDE and PSO methods. The results showed that the optimization using SaDE resulted in 15% increase in the NPV compared to that of the PSO after 10 years of production under in situ steam injection process using thermochemical reactions.

The oil production from any well passes through three stages. The first stage is the natural extraction of oil under the well pressure, the second stage starts when the well pressure decreases. This second stage includes flooding the well with water via pumping sea or brackish water to increase the well pressure and push the oil up enhancing the oil recovery. After the first and secondary stages of oil production from the well, 20–30% of the well reserve is extracted. The well is said to be depleted while more than 70% of the oil are left over. At this stage, the third stage starts and it is called the enhanced oil recovery (EOR) or tertiary recovery. Enhanced oil recovery is a technology deployed to recover most of our finite crude oil deposit. With constant increase in energy demands, EOR will go a long way in extracting crude oil reserve while achieving huge economic benefits. EOR involves thermal and/or nonthermal means of changing the properties of crude oil in reservoirs, such as density and viscosity that ensures improved oil displacement in the reservoir and consequently better recovery. Thermal EOR, which is the focus of this paper, is considered the dominant technique among all different methods of EOR. In this paper, we present a brief overview of EOR classification in terms of thermal and nonthermal methods. Furthermore, a comprehensive review of different thermal EOR methods is presented and discussed.

In this experimental study, spray and combustion characteristics of a single cylinder optical engine were evaluated by varying the fuel injection pressure (FIP) (40, 80, and 120 MPa). Karanja, Jatropha, and waste cooking oil (WCO) biodiesels were the test fuels and their results were compared with baseline mineral diesel. There was no significant difference observed in the spray tip penetration amongst all test fuels, however the spray cone angles of biodiesels were slightly higher than baseline mineral diesel. Mineral diesel showed relatively shorter injection delay compared to biodiesels at 40 and 80 MPa FIP. Jatropha and Karanja biodiesels showed higher flame luminosity at all FIPs, while WCO biodiesel showed lower flame luminosity, especially at higher FIPs of 80 and 120 MPa, primarily due to lower viscosity of WCO biodiesel. Flame spatial fluctuation (FSF) and flame nonhomogeneity (FNH) were also found to be higher for biodiesels at lower FIP of 40 MPa. Karanja and Jatropha biodiesels showed higher FSF and FNH at higher FIPs compared to WCO biodiesel.

The purpose of this research is to investigate the flow behavior inside a mixed flow type pump operating with fluids of different viscosities using computational fluid dynamics (CFD) with the goal to establish additional terms for the pump affinity laws to scale pump performance including the effects of viscosity. Several sets of fluids of different viscosities and densities are simulated under various operating conditions. The effect of viscosity on the performance of the impeller and diffuser is discussed. Changes in the pump performance due to fluid viscosity are characterized using the dimensionless flow coefficient, head coefficient, and rotational Reynolds number. The result, which can be regarded as the modified pump affinity laws for viscosity flows, was obtained based on the relationships between dimensionless coefficients. The modified affinity laws agreed well with the CFD results. Further study was conducted to validate the relationships using previously published test data for a semi axial pump design (specific speed, N s : 3869) tested with fluid viscosity ranging from 1 cp to 1020 cp and in-house testing of a split vane impeller pump ( N s : 3027) and a helicoaxial pump ( N s : 5281) using 1 cp and 5 cp viscosity fluid. The modified affinity laws accurately models the performance dependence upon viscosity. As with the standard affinity laws, a pump's functional relationship varies with each pump design. Yet the modified affinity laws produce a single common curve for all operating conditions and viscosities for a specific pump.

In this theoretical study, a fully developed laminar convective water flow in a circular tube is “convectively overloaded” toward the microscale, by decreasing the tube diameter below 1 mm. The entropy generation rate ( S ˙ g e n ) is obtained (with and without the viscous dissipation term) for a given rate of heat removal using a fixed rate of coolant (water) flow. The uniform wall heat flux and mass flux in a tube increase toward the micro-scale, which is “thermal and flow overloading,” respectively. The variations of— S ˙ g e n due to fluid friction, fluid conduction heat transfer, and their total ( S ˙ g e n , t o t ), toward the micro-scale, are analyzed. Since S ˙ g e n , t o t remains more or less the same toward the microscale, it is worth overloading a tube for miniaturization up to the laminar-flow limit.

In this paper, experimental and numerical techniques have been utilized to quantify heavy oil properties in CO 2 huff-n-puff processes under reservoir conditions. Experimentally, fluid properties together with viscosity reduction of heavy oil and interfacial properties between CO 2 and heavy oil have been quantified, while five cycles of CO 2 huff-n-puff processes have been conducted to determine oil recovery together with component variation of produced and residual oils. Theoretically, numerical simulation has been conducted to analyze the underlying recovery mechanisms associated with the CO 2 huff-n-puff processes. CO 2 huff-n-puff processes are only effective in the first two cycles under the existing experimental conditions, while the effective sweep range is limited near the wellbore region, resulting in poor oil recovery in the subsequent cycles. As for produced oil, its viscosity, density, resin and asphaltene contents, and molecular weight of asphaltene are reduced, whereas, for the residual oil, they are increased. The asphaltene component in the residual oil shows weak stability compared to that of the produced oil, while the ultimate oil recovery after the fifth CO 2 cycle of huff-n-huff processes is measured to be 31.56%.

Foam fluids are widely used in petroleum industry such as foam-enhanced hydrocarbon recovery, underbalanced drilling, and as proppant carrying fluid in hydraulic fracturing. The most important issue to be considered in foam behavior is foam rheology and specifically, apparent viscosity. Various models have been used in order to predict foam apparent viscosity; most of these equations are originally developed for suspension systems, containing rigid spherical particles, and therefore, they are unable to predict foam apparent viscosity with acceptable accuracy. In addition, the lack of a comprehensive model with usage in all foam qualities is still tangible in the literature. In this research, a new general empirical model with application in all foam qualities is proposed and validated against experimental data available in the literature. Despite the simplicity, results have near-unity correlation of determination (R 2 ), which shows good agreement of the proposed model with experimental data. Additionally, a new definition for foam quality is presented, to be more representative of the foam texture.

Polymer-gel, as a rheological complex fluid, is vulnerable to slip at solid walls. If wall slip occurs, the accuracy of viscosity measurements that are based on the no-slip boundary condition assumption is affected. This paper presents a general numerical procedure based on Tikhonov regularization for correcting Couette viscometry data in the presence of wall slip. This procedure needs only two-measurement viscosity data from two different annular gap sizes. Using the presented procedure, we determined the viscosity and wall slip behavior of a special polymer-gel used for leakage control. The results show that, the polymer-gel ZND-2 does not always exhibit significant wall slip, until the polymer content reaches a critical level of 0.3–0.5% by mass. An empirical correlation was proposed in power law form to describe the relationship between wall slip velocity and wall shear stress. It indicates that there is a minimum wall shear stress that needs to be overcome for a given polymer-gel sample manifesting wall slip phenomenon. The critical minimum wall shear stress and the gel structure strength increase drastically when the polymer content increases beyond a certain value, which is 1.0% by mass for ZND-2. When wall slip occurs, the difference is remarkable between the slip-corrected and apparent rheological parameters for different annular gap sizes. The slip-corrected rheological properties indicate that the polymer-gel ZND-2 used for leakage control behaves as a yield plastic fluid and has good shear thinning capability.