Research Paper
Chemical Engineering
behrouz Bayati; mohsen mansouri; Hossein Hejazi
Abstract
In this study, effect of ethylene vinyl acetate (EVA) as an inhibitor on wax appearance temperature (WAT) of crude oil in the Iranian oil field has been investigated using differential scanning calorimetry (DSC) method. The effect of EVA on the morphology of crude oil wax crystals has been investigated ...
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In this study, effect of ethylene vinyl acetate (EVA) as an inhibitor on wax appearance temperature (WAT) of crude oil in the Iranian oil field has been investigated using differential scanning calorimetry (DSC) method. The effect of EVA on the morphology of crude oil wax crystals has been investigated using a system designed to be equipped with an ocular microscope. The EVA inhibitor has a very good performance in reducing the Wax appearance temperature of crude oil and by adsorbing on the growing wax crystals, it prevents the crystallization process and also their connection to each other to form a network structure. By 800 ppm of the EVA inhibitor, the largest decrease occurred in the WAT of crude oil (at the rate of 26.13 ° C) and also smaller crystals and weaker structures were formed at this concentration. Therefore, 800 ppm of EVA inhibitor was selected as an optimal value
Research Paper
Siavash Ashoori; Ehsan Safavi; Jamshid Moghaddasi; Parvin Kolahkaj
Abstract
AbstractFormation damage is being reported during the secondary and tertiary stages of reservoir lifespan. One of the unpleasant sequences of formation damage caused by fine particles is permeability reduction due to pore plugging and bridging. The fine particles might exist initially in a porous medium, ...
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AbstractFormation damage is being reported during the secondary and tertiary stages of reservoir lifespan. One of the unpleasant sequences of formation damage caused by fine particles is permeability reduction due to pore plugging and bridging. The fine particles might exist initially in a porous medium, or be introduced by the external sources. In addition, there is a variety of particle types and sizes. The current research focuses on the effects of non-swelling clay minerals motions, such as the laminar ones found in Iranian sandstone reservoirs, on permeability. For this purpose, sand packs in a variety of glass bead sizes and containing aluminium oxide as fine particles were designed to scrutinize the motion of fine particles under various pressure differences, flow rates, and fine concentrations. It was concluded that for each of the three sand packs considered as the porous media in this study and composed of fine glass beads with different sizes, there is a critical flow rate which is a function of glass bead size. For the flow rates less than critical flow rate, bridges form stably and lead to the highest formation damage. After reaching the critical flow rate, the bridges weaken and then break; thereafter, relative permeability would be independent of flow rate. All in all, it was deduced that permeability reduction and formation damage are directly proportional to particle concentration, and inversely proportional to glass bead size. The reason for using solid glass spheres in this study is their flow ability, great strength, chemical stability, low thermal expansion.Keywords: Fine migration, Permeability reduction, Formation damage, Critical flow rate
Research Paper
Petroleum Engineering – Reservoir
Mohammad Ashrafi; Seyyed Alireza Tabatabaei-Nejad; Elnaz Khodapanah
Abstract
Challenges on rock absolute permeability prediction from tiny sample when laboratory apparatus is not applicable and without pore network modelling is remarkable. This prediction using the characterization of micro-computed tomography images have been studied in this paper. Twenty series of 2D micro ...
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Challenges on rock absolute permeability prediction from tiny sample when laboratory apparatus is not applicable and without pore network modelling is remarkable. This prediction using the characterization of micro-computed tomography images have been studied in this paper. Twenty series of 2D micro computed tomography rock binary images have been collected, each of them was considered as a 3D binary image. Their geometric measures in 2D and 3D for measuring image properties have been considered using Minkowski functionals and available functions, developing a regression model, absolute permeabilities have been evaluated. Some 2D and 3D geometric properties are considered. The area, the perimeter and the 2D Euler number are 2D binary images properties. The volume, the surface area, the mean breadth also known as integral of the mean curvature, and the 3D Euler Number are 3D binary images properties. Porosity and number of objects also have been considered as parameters of a regression model.To perform linear regression, twenty-four parameters were evaluated and some of them were chosen to be used. An equation is proposed based on the extensive study conducted which can predict rock permeability. This equation has two sets of parameter coefficients, one set predicts high permeability rocks (above two Darcy) and the other for low and medium permeability (less than two Darcy) which can be used for carbonated rock. Average absolute relative error for conducted cases is 0.06.
Research Paper
Hydrocarbon Reservoirs Management
TEMPLE N CHIKWE; Mudiaga Onojake
Abstract
The concentrations of trace metals in crude oil samples obtained from eight producing fields from Niger Delta Nigeria were analyzed using a 700 model Perkin Elmer Atomic Absorption Spectrophotometer. Results showed the following ranges for the trace metals, Cu (0.01- 0.04 mg/kg); Fe (0.05 – 5.90 ...
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The concentrations of trace metals in crude oil samples obtained from eight producing fields from Niger Delta Nigeria were analyzed using a 700 model Perkin Elmer Atomic Absorption Spectrophotometer. Results showed the following ranges for the trace metals, Cu (0.01- 0.04 mg/kg); Fe (0.05 – 5.90 mg/kg); Ni (0.09 – 0.72 mg/kg); V (0.008 – 1.05 mg/kg). Pb and Zn were < 0.01 mg/kg. Trace metal ratios such as V/Ni; V/Fe and V/V + Ni were used to unravel the genetic correlation among the oils. Results showed that all the crude samples except sample from Nembe South-2 have a V/N ratio < 1 indicating the organic material that produced the petroleum source rock. A cross plot of V/Ni revealed two genetic families for the crude oils, derived from a terrestrial and marine origin. This was confirmed by the Ternary plot of V, Ni and Fe which discriminated the crude oils from the producing fields into two distinct groups. The V/(Ni+V) of < 0.5 shows that most of crude oil were deposited in an oxic environment. A cross-plot of V/(Ni+V) and V/Fe showed a weak correlation which suggests that it cannot be used as a substitute for the V/Ni ratio in determining the origin and depositional environment of crude oil samples. Therefore, in-depth knowledge of the concentration of trace metals especially vanadium and nickel within an environment during oil exploration is very essential in developing new oil locations.
Research Paper
Petroleum Engineering
Meisam Hemmati; Yaser Ahmadi
Abstract
The Rock-Eval pyrolysis is a thermal method that is widely used by the petroleum geologist for evaluation of source rock characteristics and obtain geochemistry parameters. However, there are misconceptions and misuse in exceptional cases which could lead to erroneous conclusions in using Rock-Eval pyrolysis ...
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The Rock-Eval pyrolysis is a thermal method that is widely used by the petroleum geologist for evaluation of source rock characteristics and obtain geochemistry parameters. However, there are misconceptions and misuse in exceptional cases which could lead to erroneous conclusions in using Rock-Eval pyrolysis to evaluate properties of the organic matter, a cross-plot of S2 (petroleum potential) versus TOC (total organic carbon) is an usable tool which can facilitate better interpretations. The graph can apply as a criterion accuracy of geochemistry parameters, and provides the correction for S2, HI (hydrogen index), kerogen type, and measuring the adsorption of hydrocarbon by the mineral matrix. In addition, this article demonstrates a manner based on the graph to detect bitumen or hydrocarbon contaminations. Based on our knowledge about the Garau Formation as a possible source rock in petroleum geology of Iran, a geochemical study using Rock-Eval VI pyrolysis and Leco Carbon Analyzer has been conducted on samples from different outcrop sections in Lurestan province, Aligudarz region, from South-West of Iran, High Zagros. Plotting the data on a cross plot of S2 versus TOC, and determining the regression equation is the best method for determining the real values of S2 and HI parameters and measuring the contamination by bitumen or hydrocarbon. Hydrocarbon contaminations makes geochemistry data unreliable, as unrealistically increase S2 and HI, lower Tmax values, and reduce the thermal maturity level of organic matters or kerogen of source rock samples in two study locations. For skipping the effect of contamination and obtaining the real geochemistry parameters, the y-intercept of the graphs must be removed. The cause of contamination in organic rich facies of the Garau Formation is the adhesion of heavy bitumen to organic facies which is due to the covalent bonds between carbon and hydrogen ions.
Research Paper
Petroleum Engineering
Meisam Hemmati; Yaser Ahmadi
Abstract
Knowing the characteristics of suitable environments for precipitation of oil prone source rocks facilitates oil explorations and leads to development of oil fields. The current study investigates the organic matter properties and sedimentary environment conditions of the Garau Formation in various outcrop ...
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Knowing the characteristics of suitable environments for precipitation of oil prone source rocks facilitates oil explorations and leads to development of oil fields. The current study investigates the organic matter properties and sedimentary environment conditions of the Garau Formation in various outcrop sections in Lurestan province from south-west of Iran (High Zagros) with using elemental analysis, visual kerogen analysis and Rock-Eval pyrolysis data. The geochemistry parameters indicate that the Garau Formation is an excellent oil prone source rock and composed of kerogen type I and II. The oxygen index (OI) is very low which reveals that organic matter deposited in an anoxic sedimentary environment and suitable for the preservation of organic matter and hydrocarbon generation. The visual analysis of isolated kerogens from source rock samples indicates the abundance of dark amorphous organic matter (AOM) with small amounts of phytoclasts and pyrite with no palynomorphs. Sedimentation seems to have occurred in deep and reduced parts of a carbonate basin during a rapid transgression. In addition, due to the effect of thermal maturation, the color of amorphous organic matter has darkened. The elemental analysis and Van-Krevelen diagram was shown that the type of organic matter and reveals the thermal maturity of the oil window. Moreover, amount of pyritic sulfur (Sp) and organic sulfur (So) contents have been calculated, and it was reveals that the high content of organic sulfur is a key element in the structure of organic matter.
Research Paper
Petroleum Engineering
Nima Hamidian Shoormasti; Seyyed Alireza Tabatabaei-Nezhad; seyyedalireza Tabatabaei-Nezhad
Abstract
Prediction of transport parameters is an important issue in shale formations. A unique and novel method to address this subject is the Revil model (Revil et al. 2011) which has been updated here for multivalent salts. The updated model for water and ion transport through shale has been evaluated against ...
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Prediction of transport parameters is an important issue in shale formations. A unique and novel method to address this subject is the Revil model (Revil et al. 2011) which has been updated here for multivalent salts. The updated model for water and ion transport through shale has been evaluated against a range of experimental data sets. The updated Revil model only needs a few number of shale properties such as cation exchange capacity (CEC), porosity, and grain density which can be readily measured in laboratory. Also in the present work three parameters (f_Q,β_((+))^S,ν) have been considered as calibration parameters in the dynamic mode.
In addition to updating Revil model for multivalent salts, we derived equations to calculate water and ion uptake in shale sample, a simplified equation to estimate IS and a proof for the conjecture that IS correlates with ME.
The results show that in static mode, the model predicted the trend of data, however, the effect of semipermeable nature of shale on water uptake and alteration of ionic concentration in pore space was found negligible because of high salt concentrations (i.e. Cf>0.5M).
In dynamic mode, by adjusting calibration parameters for each of test data, a complete matching could be obtained. In case of adjusting all experiments with only three common calibration parameters the prediction was not satisfactory, however, the results of "intact-anion method" was more accurate than "Donnan method".
When multiple sets of ME data in a broader range of concentration including low concentrations were plotted along with high-concentration data, correlativity was significant (R2>0.9). The present study for the first time in petroleum engineering research, suggested and implemented the updated Revil model as an applied tool for investigating static and dynamic behavior of semipermeable shales.
Research Paper
Petroleum Engineering
Yaser Ahmadi
Abstract
Using nanoparticles for adsorbing asphaltene was known as one of efficient methods among researchers for upgrading of real oil samples in comparison to other expensive mechanical treatments or even solvents (such as n-pentane and n-heptane) and surfactants. In this study, Nickel zeolite oxide nanoparticles ...
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Using nanoparticles for adsorbing asphaltene was known as one of efficient methods among researchers for upgrading of real oil samples in comparison to other expensive mechanical treatments or even solvents (such as n-pentane and n-heptane) and surfactants. In this study, Nickel zeolite oxide nanoparticles have been used for asphaltene adsorption and solving asphaltene precipitation problems. Although Nickel zeolite oxide nanoparticle used in previous studies as an asphaltene adsorbent, observing relation between asphaltene adsorption on its surface and asphaltene precipitation in the presence of nanoparticles was not covered. Series of experiments include FTIR, CO2-oil IFT tests, Langmuir and Freundlich isotherm models, and natural depletion tests were performed in the presence of Nickel zeolite oxide nanoparticles. Adsorption data was fitted well with the Langmuir model in comparison to the Freundlich model which shows that the adsorption occurs in a homogeneous surface with monolayer coverage. Based on the CO2-oil IFT results, there are two different slope forms in IFT readings as pressure increase from 150 Psi to 1650 Psi. Second slope (900 Psi-1650 Psi) is slower than the first one (150 Psi-900 Psi) which was due to aggregation of asphaltene. Three pressures of 1350 Psi, 1500 Psi, 1650 Psi and Nickel zeolite oxide nanoparticles at concentration of 30 ppm were selected for performing natural depletion tests and the basis of selection was high efficiency of adsorption in these points. As pressure decrease from 1650 Psi to 1350 Psi, asphaltene precipitation changes from 8.25 wt % to 10.52 wt % in the base case and it was 5.17 wt % to 7.54 wt % in the presence of Nickel zeolite oxide 30 ppm. Accordingly, Nickel zeolite oxide nanoparticles adsorbed asphaltene on its surface in proper way and the amount of asphaltene precipitation was decreased in the presence of Nickel zeolite oxide nanoparticles.
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