فهرست مطالب

Petroleum Science and Technology - Volume:8 Issue: 3, Summer 2018

Journal of Petroleum Science and Technology
Volume:8 Issue: 3, Summer 2018

  • 88 صفحه،
  • تاریخ انتشار: 1397/03/12
  • تعداد عناوین: 6
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  • Abolfazl Moradi*, Behzad Tokhmechi, Vamegh Rasolui, Mohammad Fatehi Marji Pages 3-13
    The combination of horizontal drilling along with hydraulic fracturing has significantly improved the production of hydrocarbon reservoirs and made it possible to extract the relatively impermeable and uneconomical reservoirs. The production rate of oil and gas wells increases proportional to hydraulic fracture aperture or crack opening displacement (COD). This is an important parameter in fracture mechanics literature and hydraulic fracturing of hydrocarbon reservoirs. Despite the significance of COD there are a few analytical solutions for the estimation of COD under certain conditions. In this paper the effect of various parameters on COD is investigated semi-analytically. A higher order displacement discontinuity method is used to consider the effects of different parameters (Young’s modulus, Poisson’s ratio, internal pressure, maximum and minimum horizontal stresses, crack half-length and its inclination with maximum horizontal stress) on the COD in a hydraulic fracturing process under arbitrarily conditions. The coefficient of determination and standard error of the estimate were 94.35% and 4.37×10-4
    Keywords: Crack opening displacement, hydraulic fracturing, higher order displacement discontinuity method, crack propagation
  • Sayed Mohsen Hosseini*, Hengameh Alibakhshi, Ali Reza Khodabakhshi, Mahsa Nemati Pages 14-29
    Polyvinylchloride (PVC) based heterogeneous cation exchange membranes were prepared by the solution casting technique. The effect of super activated carbon nanoparticles concentration as filler additive in membrane matrix on ionic transfer behaviors of the membrane was studied. SOM images showed uniform particles distribution and relatively uniform surfaces for the membranes. The membrane water content was improved initially by using of super activated carbon nanoparticles up to 0.5 %wt in the casting solution and then began to decrease by more increase of nanoparticles content ratios from 0.5 to 4 %wt. Utilizing of activated carbon nanoparticles in the casting solution also led to increase of water contact angle, membrane ion exchange capacity, fixed ionic concentration, membrane potential, transport number and membrane selectivity obviously.An Opposite trend was observed for the membrane electrical resistance. The sodium flux/permeability was also enhanced initially by increase of nanoparticles concentration up to 0.5 %wt and then decreased slightly by more increase of nanoparticles loading ratios from 0.5 to 1 %wt. The sodium flux was sharply enhanced again by more increase of nanoparticles concentration form 1 to 4 %wt. The membrane transport number and selectivity were increased initially by increase of electrolyte concentration and then showed decreasing trend. The membranes showed higher transport number and selectivity at neutral pH compared to other pH values. The ED results showed that dialytic rate of lead ions was increased by utilizing of super activated carbon nanoparticles in the membrane matrix.
    Keywords: Cation exchange membrane, Super activated carbon nanoparticles, Mixed matrix, Ionic transport property, Electrodialysis
  • Ahmed Zoeir*, Jafar Qajar Pages 30-41
    Despite advancements in specifying 3D internal microstructure of reservoir rocks, identifying some sensitive phenomenons are still problematic particularly due to image resolution limitation. Discretization study on such CT-scan data always has encountered with such conflicts that the original data do not fully describe the real porous media. As an alternative attractive approach, one can reconstruct porous media to generate pore space representations. The reconstructed structures are then used for simulations using some sort of discretization. In this paper, It is examined the effect of discretization on porosity and saturation calculations in porous media models. Some 3D Boolean models of random overlapping spheres of fixed and variable diameters in three dimensions are used. The generated models are then discretized over 3D grids with different number of voxels. The porosity can be calculated and saturation of the discretized models are then compared with the analytical solutions. The results show that when meshgrid sizes are 8% of smallest grains, porosity is calculated with 95% precision. In addition to that, meshgrid sizes of 5% and 3% of average grain diameter are adequate to calculate non-wetting and wetting phase saturations with at least 95% precision. This helps in choosing the optimum voxel size required in imaging for efficiently use of available computational facility
    Keywords: Boolean Model, Discretization, Model Porous Media, Porosity, Saturation
  • Effat Behboudi*, Nasser Keshavarz, Asghar Naderi Pages 42-52
    The presence of gas hydrate and associated gas in the Makran Accretionary Prism, offshore Iran, has been confirmed by various seismic indicators, including the bottom-simulating reflector (BSR), amplitude blanking, and bright spot. The pre-stack analysis and the study of amplitude-variation-with-offset (AVO) attributes are the most reliable tools for semi-quantitative study of gas hydrate and free gas resources. Due to the lack of well data in the most regions of gas hydrate accumulations in deep oceans, the study of AVO attributes and application of seismic inversion techniques are solutions to evaluate both gas hydrate and the free gas trapped beneath it. Conventional seismic stacked data increases the signal-to-noise ratio; however, amplitude stretching in far offsets resulted in normal move-out (NMO), and Poisson’s error in velocity analysis decreases the frequency content of stack section. Moreover a stacked seismic data do not present a real zero-offset seismic data. In this study, the AVO intercept section was used to remove far offset effects and produce a more realistic zero-offset section with a high frequency content. Consequently, the acoustic impedance produced from the inverted intercept section shows acoustic property of the sediment in a better accuracy. According to the inverted section from AVO intercept data, free gas zone, and double bottom-simulating reflector, which identified about 50 ms below the first BSR, were observed with high vertical resolution.
    Keywords: Amplitude, variation, with, offset (AVO), Intercept Attribute, Gas Hydrate, Free Gas, Double Bottom, simulating Reflector (DBSR)
  • Seyed Saied Bahrainian, Amin Nabati*, Ebrahim Haji Davalloo Pages 53-71
    In this study, predictive capabilities of apparent viscosity of oil-based drilling fluids which is used in National Iranian South Oilfields Company (NISOC) were evaluated using Newtonian and non-Newtonian models to drive a new suitable equation. The non-Newtonian models include Bingham plastic, Power law, Herschel-Bulkley, Casson, and Robertson-Stiff. To validate the results, the calculated viscosity from rheology models was compared to the fann 35 data of viscometer. The results showed that Robertson-Stiff model has the best prediction of shear stress and viscosity with an absolute average percent error of 3.58. This was followed by Herschel-Bulkley, Casson, Power law, Bingham plastic, and Newtonian with the absolute average percent error of 3.68, 3.77, 9.04, 20.09, and 44.02 respectively. Therefore, the new equation was proposed to predict the shear stress for oil-based drilling fluids which is used in Southwestern Iranian Oilfields. In comparison to the results of the experimental data of this study, it was revealed that the proposed equation has a good agreement with the real shear stress and apparent viscosities.
    Keywords: Oil, Based Drilling Fluids, Rheological Models, Fann 35 Viscometer, Shear Stress
  • Vanessa Cristina Santanna, Tereza Neuma Castro Dantas, Allan Martins Neves, Juliana Rocha Dantas Lima, Camila N., Oacute, Brega Pessoa Pages 72-80
    The performance of petroleum recovery methods is dependent on the characteristics of the reservoir rock, oil quality, and formation water. One fundamental feature for considering petroleum recovery methods is the wettability of the rock reservoir. Also, this feature impacts the displacement of fluids in the rock reservior. In the case of the limestone, which normally features oil wettability, enhanced recovery methods are responsible for altering surface wettability. In this study, the effect of concentration of a cationic surfactant in the oil recovery from limestone is shown. In these tests, finite-bath technique was used to investigate adsorption by varying the amount of adsorbent and contact time. By carrying out contact angle assays, the wettability of the limestone was assessed. In addition, the oil recovery was effected by spontaneous imbibition. In this study, the limestone samples with solutions of CTAB in the concentrations of 0.8596 g/L and 1.2280 g/L, using a 2% KCl solution are treated. The results showed enhanced adsorption of CTAB at the CMC. The nature of this phenomenon did not induce changes in the wettability of the rock, which was confirmed by the contact angle measurements. In the spontaneous imbibition, more oil could be recovered when using a CTAB below the CMC, possibly due to less intense adsorption by the limestone.
    Keywords: Imbibition, Surfactant, Oil Recovery, Adsorption, Limestone