PETROLEUM RESEARCH
Year:2019 | Volume:27 | Issue:103 |Papers Count:12

Fluid is more mobile in high permeable media than low permeable one; therefore، the acid movement is faster in the first one. This is important because low permeable media often need acidizing treatment. At this stage، a diverter agent such as nanoparticle is felt to move the acid to the low permeable areas. Performing tests for specific conditions in the laboratory requires time and cost. Probably sometimes، a test can also be repeated several times to improve the results. Also، the effect of specific parameters on each other and the results of the test are also unknown. So for these reasons، modeling work is needed and should be done. The simulation of conventional acid injection was performed to determine the breakthrough volume of the acid without diversion. Next، the properties associated with nanoparticles such as the movement of nanoparticle in the medium based on the Random Walking Particle Tracking theory are studied. In addition، a model for investigating attachment and detachment of particles from surfaces is employed. The gel generates resistance against the high perm zone which causing acid diverts to low perm media. The amount of gelling creation depends on aggregation term. The change in the viscosity of the fluid is measured by using Krieger viscosity model. In addition، finally، acid will be converted into diverting acid. One important finding of this study is that usage of gelling acid leads to less Breakthrough volume، Thus the usage of gelling acid is found to be more efficient than using conventional acid. Moreover، the addition of nanoparticles decreases the average breakthrough volume up to 50%.

In this research، the performance، efficiency، and properties of anti-fouling and flux of poly vinylidene fluoride (PVDF) nano-composite membranes with concentration of 15wt. % and 18 wt. %، mixed with different functional carbon nanotubes (-OH،-COOH،-NH2)، were made and studied using phase inversion and normal methylpyrrolidone (NMP) solvent; moreover، the nano-composite membranes tested for flux، fouling، contact angle، porosity and protein rejection rate. Also، by using empirical test results، (1) flux and (2) fouling parameters were modeled based on the input variables including nanoparticle percentage، polymer percentage، porosity، contact angle and protein rejection rate. In this model، four intelligent systems including multiple layer percepton، radial basis function، least squares support vector machine and adaptive neuro-fuzzy inference system and three optimization algorithms including generic algorithm، simulated annealing and particle swarm optimization have been used. The results showed that for both flux and fouling parameters، the best models are GA-RBF and Conjugate-ANFIS with high correlation coefficient. In the next section، modeling was used to obtain optimal values of the best models made for both outputs (minimum fouling and maximum flux) and then the combined algorithm of the genetic algorithm and particle swarm optimization values were obtained. Afterward، by using optimization results for each type of polymer (15wt% and 18wt%)، the membranes were made in the laboratory، and then flux، fouling، contact angle and porosity tests were performed، and the results were compared with the results of the model. Finally، the results showed that 0. 07 wt. % single-walled carbon nanotube-PVDF nanocomposite membrane functionalized with hydroxyl group and 0. 17 wt. % single-walled carbon nanotube-PVDF nanocomposite membrane functionalized with hydroxyl group had the best performance with the polymers of 15 wt. % and 18 wt. % of PVDF respectively.

In this research، the image log techniques along with full set logs and geophysical data have been used to investigate reservoir quality of the Sarvak Formation reservoir in an oilfields of Persian Gulf. Image log analysis on 4 selected wells (A، B، C، and D) of studied oilfield show that the structural dip of the Sarvak Formation Reservoir base on 129 readings are 11 degree toward N69W with strike of N27E and S27W. Moreover، two main fractures type are recognized in the studied reservoir. The first has been seen in wells named A، B and، C that have the dip of 81 degree toward N38E with Strike of N25S/S52E base on 489 readings. The second one is related to well name D and has the dip of 64 degree toward N58W with Strike of S32W/N32E base on 110 readings. Also، geophysical data in studied oilfield show 2 main faults with North-South trends and 11 local faults with Northwest-Southeast trends. The correlation of fracture trends identified in image logs with faults’ trends of oilfield indicate that the trend of theses fractures correlate well with the trend of local faults. Models of porosity، permeability، fractured density with openness of fractures of the Sarvak Reservoirs indicate that the effects of local faults in fractures of oilfields are important and caused the increase in quality of reservoirs in wells B، C، and D. Based on image log data، the maximum and minimum of in-situ horizontal stress in oil reservoir have been estimated from N32W and S55W respectively.

The Asmari Formation، in the Aghajari Oilfield (located in the Dezful Embayment) with about 400-meter thickness، was deposited in a homoclinal carbonate ramp and affected by various diagenetic processes. Core studies، microscopic thin sections and Scanning Electron Microscope images (SEM) from the 5 wells indicate that dolomitization is one of the most effective diagenetic processes of the reservoir quality of the Asmari Formation، and dolomitization mainly affects the upper parts of this Formation. In addition، five types of dolomites including (1) Dolomicrite (62 micron)، (4) floated dolomites in the fine grain matrix، and (5) dolomite cements are recognizable. Each type of these dolomites have different effects on the trend of mercury injection curves (Pc)، and therefore on the reservoir quality of the Asmari. Moreover، dolomicrospars are the most common type and have high porosity and permeability (average 16% and 35 mD respectively) due to the presence of intercrystaline porosities. Therefore، they can be saturated by mercury under low entry pressures (about 5 psi)، and then show high-steep capillary pressure curves. Dolomicrites due to fine-grain nature have initially high porosity and relatively low permeability (11. 5% and 4 mD respectively). But in along with dissolution، they show reservoir characteristics similar to Dolomicrospars، and their Pc curves shift to the left. Floated dolomites in matrix have no considerable role in the reservoir quality. Moreover، dolospars due to over-dolomitization and locking dolomite crystals، and dolomite cements due to disconnecting pore spaces led to decreasing in porosity and permeability. It seems zones 1 to 3 of the Asmari Formation in the Aghajari Oilfield have more potential for drilling and well-completion in the future because of more concentration of dolomicrospars and vuggy dolomicrites.

In this research، blending nanofiltration membranes based on polyethersulfone (PES)/poly vinylidene fluoride (PVDF) were prepared by using phase inversion method. PVDF has high piezoelectricity property in comparison with other polymers، so its blending with other polymers produces new structure membranes with appropriate fouling resistant. Moreover، the effect of different PVDF concentrations in the casting solution on membrane performance was studied. The flux، salt rejection and water content measurements and also scanning electron microscope (SEM) and FTIR analysis were carried out for the membrane characterization. Obtained results showed that water content and porosity were initially increased and then decreased. Also، the results demonstrated that the permeability flux and the pure water flux of PES/PVDF blend membranes were higher than pristine PES membrane. The salt rejection has improved up to 20%، when the concentration of PVDF is 0. 5 wt. %.

One of the enhanced oil recovery methods that has been recently received more attention is low salinity water injection (LSW). Among the proposed mechanisms to describe LSW، geochemical reactions seem to mainly affect rock wettability alteration and thus incremental oil recovery. The goal of this paper is to investigate the effect of geochemical reactions of calcite dissolution and ion exchange on the performance of LSW in a sandstone reservoir by using the concept of threshold salinity. Fluid flow equations according to Buckley-Leverett theory were numerically coupled with the PHREEQC software. Results showed that as LSW was injected، initial equilibrium between reservoir rock surface and aqueous phase was disturbed leading to calcite dissolution and also cation exchange between aqueous phase and rock surface. Analysis of geochemical reaction near the injection well showed that cation exchange may cause to separation of organic compound from rock surface leading to wettability alteration to more water-wet. Also، pH profile through the reservoir showed that rate of calcite dissolution was very high near injection well، but only partial dissolution of calcite induced by cation exchange occurs at farther distance. Fractional flow analyses in line with total salinity profile showed that two distinct saturation shock fronts were established during LSW injection: first one represents high salinity condition with a water saturation of 0. 43، and the second one represents low salinity condition with a water saturation as much as 0. 58. Under the conditions of this study and selection of a salinity threshold of 3000 ppm، such increase of water saturation reveals EOR potential of LSW by which an incremental oil recovery of 10% of the oil initially in place was obtained as compared to high salinity water injection.

Phenol and its derivatives are considered as one of the major environmental pollutants especially in aquatic ecosystems due to its toxicity، carcinogenic effect، and low biological degradation. The aim of the present work is to compare three carbon nanoadsorbent in phenol removal from water and to investigate adsorption kinetics. In this regard، Graphene، CMK-3، and multi-wall carbon nanotube (MWCNT) were selected while several techniques such as X-ray diffraction (XRD)، Brunauer– Emmett– Teller (BET)، Barrett-Joyner-Halenda (BJH) and scanning electron microscope (SEM) were used to characterize the adsorbents. In the next step، the effective factors on the adsorption process، i. e. adsorbent dose، pH، and contact time were studied. Moreover، the kinetics of the phenol sorption process were tested using the Pseudo-first-order، Pseudo-second-order، and Elovich models. The results have shown that increasing the amount of adsorbent loading leads to increase the adsorption efficiency and decrease in adsorption capacity، both variations indicating nonlinear behavior. Furthermore، the highest removal for graphene، MWCNT and CMK-3 was observed at pH 8. It has also been found that the optimum time to saturate adsorption active sites is about 40 minutes، and more contact time does not change the process efficiency. In addition، kinetic study has indicated that for all adsorbents، pseudo second order model has fitted better the experimental data than Pseudo first order and Elovich models. The adsorption mechanism was discussed based on experimental results. The results have indicated that for all adsorbents، the p-p interactions is an important parameter whereas in the case of MWCNT، strong force between phenol and copper impurities; moreover، in the case of CMK-3، strong hydrogen bond between phenol and hydroxyl/carboxyl groups are important parameters in in the adsorption process. Finally، among the adsorbents، CMK-3 has been selected as the optimum adsorbent for phenol removal due to its higher yield and efficiency.

Velocity analysis is an important part of seismic data processing steps. The stacking velocity can be calculated by the Normal-Incident-Point (NIP) wave and the emergence angle، which are attributes of Common-Reflection-Surface (CRS) stack method. But the NIP-wave is impressed by the Normal wave of the CRS attribute. The Common-Diffraction-Surface (CDS) stack is introduced by developing the CRS method. The model-based CDS attributes can be calculated by ray tracing on smooth velocity model with minor accuracy. As in model-based CDS method، the NIP-wave is not affected by N-wave. Hence، the calculated stacking velocity is more accurate and more reliable. Here، it is proposed by us to apply the model-based CDS on a range of constant velocity model several times. In this way، the coherence and stacking velocity sections are produced for each time. In addition، the production of coherence and stacking velocity sections allows us to select the stacking velocity with high coherence. Finally، the propose method on a synthetic model with five layers has been applied and the results of stacking velocity obtained by CRS have been compared with the results obtained from model-based CDS method. The results show a great improvement in accuracy of stacking velocity calculated with CDS attributes.

In this paper، the experimental and the numerical results of a porous media burner containing spherical alumina particles are investigated and also are compared with each other. Based on the data، the maximum production of hydrogen mole fraction and the maximum conversion rate of methane to hydrogen and carbon monoxide have been investigated. Moreover، the results show a good agreement between experimental and numerical methods. The optimum efficiency of the burner is calculated and shows that under good input conditions، the maximum hydrogen production can be achieved with a relatively optimal 75% energy efficiency. It has been shown that despite the significant effects of equivalence ratio on output characteristics parameters، which are considered by many researchers in their papers، other input parameters such as released energy، reactor size، particle diameter (porosity) and the permeability of medium are important and effective on the maximum production of hydrogen.

Sedimentary basins have always been considered as one of the prerequisites for the presence of hydrocarbon resources، and the study of the geometry of these basins has always been of great importance. In this paper، subspace method has been used for non linear inversion of gravity data for the basement modelling. That is the high stability in contrast the noise and efficiency of the method for inverse modelling of geophysical data. The subspace method is based on successive iterations، and at each iteration، a perturbation of model parameters in a p-dimensional subspace of an m-dimensional model space is sought. The primary model is updated using the perturbation values of the model parameter. So، inversion in successive iterations used the one step of obtained result in previous step which is the same as primary model. Basis vectors of P-dimensional subspace are extracted by the SVD of a second derivation of model parameters. M-dimensional model space is projected onto P-dimensional subspace using basis vectors. The practical effectiveness of this method is demonstrated by inversion of synthetic and real examples. The real gravity data is acquired over the Carlisle England Area. The results have been compared with those of geological section at the study area.

One of the methods of increasing oil production is miscible gas injection. The most important parameter in the design of miscible injection method is to determine and calculate the minimum miscibility pressure. In order to obtain the best oil production، the injection operation pressure or the range of miscibility pressure should be at above. Moreover، in this method، the calculation and prediction of the minimum miscibility pressure is a very important parameter. In this study، to simulate the process of gas injection in to the reservoir and to investigate the condition of miscibility، the available laboratory information and model of slim tube were used in Petrel (Eclipse 300) software in a single porosity model. After modeling fluid properties using Winprop Software، the appropriate outputs were made to be used with Eclipse 300 Simulator. Then by simulating the injection of fluids with different composition in the reservoir fluid، the MMP value was calculated for each of the modes. In order to do that، the gas was combined with different proportion of gas condensate، and by considering the reservoir pressure، the optimum injection composition in the reservoir oil was determined. Finally. the sensitivity analysis was made on the parameters which influence the gas injection process.

Water resources pollution with petroleum hydrocarbons is one of the most important problems in clean water supply for drinking and sanitary purposes. In this study، the simultaneous reduction of salinity and PAH (benzene and toluene) from the contaminated water has been investigated with membrane process (Forward Osmosis) coupled with photocatalysis. The amount of membrane flux، and the treatment efficiency of toluene and benzene through three various membrane including PES، CTA and CTA/TiO2 have been investigated. Based on the results from three types of membrane، the amount of toluene and benzene removal in combined method has been seen 74% and 41% respectively. Also، membrane surface modification with nano-photo catalyst particles has reduced membrane fouling; moreover، the membrane surface has increased membrane flux، and removed benzene and toluene from feed water.