PETROLEUM RESEARCH
Year:2018 | Volume:28 | Issue:101 |Papers Count:16

Measurement of temporal-spatial distribution of surface subsidence as a result of production from hydrocarbon reservoirs is a relatively common practice worldwide; however، it is set aside in Iran، although it seems that prediction of subsidence trend at the beginning of the reservoir life can be beneficial in future production estimates. In this paper، the accuracy of the numerical modeling for calculating subsidence process is evaluated by comparison with the in-situ measurements recordings، as well as those designated from analytical solutions for two hydrocarbon reservoirs in the USA، and the Netherlands. It was observed that the numerical simulations can well trace the subsidence trend in spite of elastic behavior assumption، and other simplifications considered. Although، the real mechanism of subsidence is inelastic، and parameters variations are possible. Afterwards، the distribution of temporal-spatial surface subsidence in a specified zone of Kupal oil field، Iran، was predicted. Moreover، unlike the verification examples، in which pressure changes in the whole reservoir had been considered to determine settlements، the “ production history” of some wells was used in the simulations. It was concluded that production from the selected area in the Kupal oil field has resulted in surface subsidence in the range of 26 to 32 cm in the period between years of 1372-1396.

In this research، HZSM-5 zeolite was made in medium containing fluoride ions، and its performance in the process of methanol to propylene conversion was investigated. Potassium fluoride was used as the supplying material for this ion. Physical-chemical properties of catalysts were determined by using XRD، FESEM، N2 adsorption/desorption and NH3-TPD analysis. The XRD pattern confirmed the formation of crystalline structure associated with zeolite HZSM-5 in potassium fluoride-synthesized zeolite (F-HZSM-5 specimen). FESEM images of F-HZSM-5 zeolite showed a change in morphology and an increase in particles size compared to the reference sample HZSM-5. Results of the NH3-TPD analysis showed a reduction in the concentration of total acid sites in the F-HZSM-5 zeolite. The activity of the samples in a fixed-bed reactor and in the same operating conditions was investigated. The F-HZSM-5 catalyst showed less lifetime in comparison with the reference sample. However، this catalyst over a period of 10 days had an average selectivity of propylene and a propylene/ethylene ratio of 41. 8 and 10. 9، respectively.

Nowadays، a wide-range of EOR methods are used to enhance oil recovery from carbonate reservoirs. They arethe most scattered reservoirs all over the world. Smart water injection is one of the popular and newest methods in EOR. It controls the wettability of rocks. In this study، wettability alteration and the rate of wettability modification are investigated by zeta potential and contact angle experiments. Smart water is a kind of water with controllable salinity and ion concentration. In this regard، five different samples of smart water were synthesized by different concentrations of SO42-، Ca2+، Mg2+ ions، based on Persian Gulf seawater TDS. Then، the results were compared to those obtained from formation water and seawater، as the blank samples. The ability of the smart waters in controlling rock wettability was examined by pursuing of zeta potentials in the presence of different water samples at ambient condition. According to the results، the zeta potential of carbonate sands in the presence of water samples SW#4SO4، SW#2SO4، SW، and formation water was-9. 61،-7. 13،-1. 25 and15. 8، respectively. The data suggested that the samples SW#4SO4 and SW#2SO4 are the two most effective smart water samples in wettability alteration. After that، the most capable smart water samples with the most negative zeta potential was selected to be used for the contact angle experiment. The results showed that، in the presence of SW#4SO4، SW#2SO4، SW and formation water، the final contact angle decreased from their initial values (144. 23° ، 149. 68° ، 136. 63° ، and 139. 89° ) to 87. 10° ، 105. 17° ، 135. 66° ، and 143. 13° ، respectively، which is in a good agreement with the results of zeta potential. These data showed that the amount of sulfate ions in the smart water can control the wettability of rock from oil to water-wet state.

Injection of nanofluids in oil reservoirs is one of the new methods for increasing oil recovery. The stability of these fluids in reservoir conditions and negligible formation damage، along with the significant increase in oil recovery are the factors which influence the selection of suitable nanofluids for increasing oil recovery in harsh reservoir condition. In this study، the efficiency of three nanostructures: nano-gamma-alumina، iron(III) oxide and silica with concentrations of 200، 500 and 600 ppm and with two different mixture ratios of formation water and reservoir injected water in a brine with a salinity of 106000 ppm to 234000 ppm، and a temperature of 90° C in oil extraction from oil-wet، media has been studied. In this part of the study، by conducting two-dimensional flow experiments in a glass micromodel at ambient temperature and atmospheric pressure، the displacement of oil by injecting fluid was studied، and the mechanisms of the performance of nanofluids were investigated for enhancing oil recovery. Zeta potential of the fluids was measured for the reservoir pressure and temperature (T= 90° C، p=2700 psi) to insure stability of the fluids. The results of these experiments showed that injection of all three nanofluids can enhance oil recovery up to 20% in comparison to that for the injection of brine. The highest amount of recovery was recorded for alumina nanostructure and then for iron oxide and silica respectively. Due to the slight change in the viscosity of nanofluids compared to water injected، and also the negligible change in the interfacial tension of the aqueous-oil phase for alumina and silica nanofluids، and the results of static tests for determining the contact angle، the mechanism change of wettability to water wet condition seems to be the dominant mechanism for alumina and silica nanofluids for this increase in oil recovery. Considering the slight change of iron (III) oxide nanofluid and results of pendant drop test for interfacial tension measurement of the nanofluid، the reduction of interfacial tension of water-oil phase for iron (III) oxide nanofluid may be reported as the dominant mechanism of enhanced recovery. The formation process of emulsion with iron (III) oxide nanofluid and oil is a confirmation of this mechanism for iron (III) oxide nanofluid.

Recently، in consequence of the decrease in easy access to crude oil reservoirs، oil and gas industry has fouced on production from heavy oil and exhausted reservoirs (low pressure reservoirs). Drilling in low pressure reservoirs is associated with many technical and economical problems that occasionally make these fields economically unprofitable. Most of the problems include uncontrollable lost in fracture and formation damage in production zone. Drilling fluid plays a significant role in achieving the appropriate drilling technology as penetration of the drilling fluid in formation results in reducing the productivity of the well especially in depleted reservoirs. Multi-layer micro-bubble fluids or aphrons have been used in recent years as a part of water base and oil base drilling fluids. Their effect on reducing the formation damage has been observed in application. It should be noted that these fluids are suitable for drilling of depleted reservoirs because of their bridging properties. In this study، in order to determine the optimal stability conditions of factors such as: type of polymer، polymer concentration، surfactant concentration، pH، salinity، mixing time and RPM using Taguchi experimental design with L36 array (two parameters in two levels and five parameters in three levels) Were optimized. Then، the effect of the concentration of polymer and surfactant on rheological properties was studied and the optimal fluid was selected for damage testing، and the return permeability of the micro-bubble fluid was compared with the base polymeric fluid. A micro-bubble fluid with a concentration of 3 pounds per barrel of XG and 1 pound per barrel of SDBS showed the most stablilty and most stable rheological properties. Micro-buble fluid also showed a better performance in evaluating pressures in formation damage test in comparison with polymer base fluid both return permability wise and shut-off wise.

In this study، equilibrium and kinetic adsorption of 4، 6-DMDBT removal from model fuel، using an acid treated activated carbon is investigated. The equilibrium adsorption capability of this adsorbent is investigated. The equilibrium adsorption data fitted by Freundlich and To `th isotherms. The kinetic adsorption is also investigated by using two kinetic models: intraparticle diffusion model، and homogeneous surface diffusion model (HSDM). The results have shown that the experimental equilibrium adsorption data were fitted very well with both Freundlich and To `th isotherms. Homogeneous surface diffusion model، very well fitted kinetic experimental data. Mathematical modeling of the process using HSDM results in values of mass transfer and diffusion coefficients as 2. 5558×10-2 m⁄ min and 3. 4056×10-6 m2⁄ min for 4، 6-DMDBT adsorption، respectively. HSDM also reveals that both boundary layer diffusion and diffusion into pores of adsorbent are present at the rate-limiting step of the adsorption process.

USY zeolite as a crucial component in FCC catalyst has been modified via post-synthesis acid treatment applying acetic acid، oxalic acid، and hydrochloric acid in order to increase mesoporosity and more pore accessibility. Acid leaching was performed under two different conditions including room temperature and reflux. Extra-framework Al atoms were removed which was confirmed through XRD، SEM، ICP-OES and N2 adsorption-desorption isotherm analyses. Elemental analysis showed increasing in SiO2 to Al2O3 ratio. Examining surface area and pore volume through BET-BJH and t-plot methods showed that total surface area، as well as mesoporous volume، were increased by acid-treating in all modified zeolites. The mesoporous surface was increased from 52. 62 in primary zeolite to 115. 09 m2/g in the sample which was acid leached through oxalic acid at room temperature. Moreover، the total surface area of the zeolite was increased from 684 to 743 m2/g. All modified zeolites were applied in the preparation of FCC catalyst. Catalytic cracking of VGO indicated a considerable increase in gasoline yield upon modified catalysts. Gasoline yield was increased from 18 wt. % over FCC to 40 wt. % in acetic acid-modified zeolite at room temperature.

The most important mechanism of microbially enhanced oil recovery processes is changes in interfacial properties of fluid/fluid/rock affected by bacterial cells and their metabolites. In this study، two bacteria B. licheniformis and P. putida and three different sources of carbon were used. Results showed that due to the effect of carbon source on bacterial growth and also type and value of produced metabolites، changes in interfacial properties of fluid/fluid/rock is affected by used carbon source. The better growth of both bacteria occurred in a culture medium containing glucose. Pendant drop tensiometry، electrophoretic mobility measurement، interfacial dilational rheology and contact angle test were used to investigate the effect of cell structure and culture medium composition on interfacial tension reduction، emulsion stability، and wettability alteration mechanisms. The results of this section showed more potential of P. putida bacteria in surfactant production. Also، results showed that glucose is a better culture medium for B. licheniformis bacteria. Produced biosurfactants and bacterial culture of B. licheniformis bacteria in medium with glucose carbon source reduced surface tension and interfacial tension by 29. 07% and 43. 87%، respectively. Submerging thin section in glucose culture medium of B. licheniformis bacteria reduced the contact angle of water drop from 109. 081 to 44. 898° . In the case of P. putida bacteria، the oily and glucose culture media are respectively the effective media for influencing the fluid-fluid and fluid-rock interface. The produced biosurfactants and bacterial culture of P. putida bacteria in medium with olive oil carbon source reduced surface tension and interfacial tension by 36. 4% and 27. 1%، respectively. The contact angle of drop water was reduced from 109. 081 to 54. 050° in glucose culture medium of P. putida bacteria

The addition of Zinc to the synthesis of ZSM-5 catalysts (Si/Al=21) was studied in xylene isomerization reactions. Physicochemical characteristics of the prepared catalysts were evaluated by XRD، BET، SEM، FTIR، NH3-TPD and TG analyses. Zn incorporation strongly increased the strong acid (Brø nsted) sites and reduced the weak acidity (Lewis). Higher strong acidity led to higher PX yield and Lower weak acidity led to lower coke formation and more catalytic stability. (0. 5 wt. %)Zn-ZSM-5 as an efficient and stable catalyst for xylene isomerization reactions demonstrated high PX yield (18. 5 wt. %)، high EB conversion (43. 6%) and low xylene loss (3. 3 %).

The prediction of drilling rate is one of the important issue because of its role in minimizing drilling costs to optimize the drilling process. Field data analysis is a key element in reducing costs and improving drilling operations. Furthermore، developing field information analysis tools and providing prediction modelsare two alternatives to improve drilling operations. When a drilling system is deployed، there are only a few limited parameters which can be controlled and changed. In general، the main purpose of this research is to apply intelligent techniques and provide graphical tools for predicting drilling performance. For this purpose، a database of field data such as well depth، drill weight، drill speed، drill chuck، weight on the hook and the torque was established from one of the southern fields of Iran. In this research، two different types of graphical tools were proposed to predict the drilling rate of penetration as well as to calculate the cost per foot، using a fuzzy neural network and Neuro-fuzzy approaches. The goals of the economic evaluation are the drill performance and the cost-per-foot calculation. The results showed that a good correlation coefficient (R2=0. 94) was obtained to predict the penetration rate using the neural network. In order to improve the findings، the fuzzy neural network method was applied. The results demonstrated that a very good relationship with high precision having a coefficient of determination (R2=0. 99) was obtained and thereby it depicted a significant improvement in the accuracy of the prediction models.

Single-criterion techniques in which just a single objective is considered cannot offer the perfect solution because they cannot take into account the trade-off between conflicting technical and economic conditions. In this study، a multi-criteria algorithm was developed based on experimental design methods، particle swarm optimization، and fuzzy logic. It was able to solve the optimization problem via considering different objectives simultaneously، finding the optimum values of effective factors. To evaluate the efficiency of the workflow، a case study was done in which influential parameters (water flooding duration، polymer concentration، duration of polymer injection، and polymer adsorption) for the design of an enhanced oil recovery operation of polymer flooding in a sandstone reservoir were optimized considering technical (cumulative oil production) and economic (net present value) objectives. The results were compared to the results of the base-case scenario as well as a single objective algorithm (particle swarm optimization). Compared to the base-case scenario، cumulative oil production increased more than 58% and net present value rised from $ 6. 9 to 13. 1 MM as well. Although the optimum scenario proposed by single-criterion optimization algorithm based on technical objective produced more oil compared to the best solution of the multi-purpose algorithm، a severe reduction was observed in the economic objective simultaneously. Finally، the results of this study demonstrate that multi-objective algorithms are more applicable to precise and realistic decision-making.

To reduce corrosion، choosing proper coating for the outer surface of oil and gas transportation pipelines is considered the most important part in developing a protection system. The issue of cathodic disbondment is one of the problems of pipeline coatings which is caused by impressed cathodic current and generation of alkali environment at the coating-metal interface and result in coating disbondment. In this research، three coating types including، 3-layer polyethylene، polyurethane، and dual fusion bond epoxy powder are investigated and their physical، chemical، and mechanical properties are studied. The results of cathodic disbondment with simulating long-term working conditions provide an appropriate view on coatings behavior at long-term service exposure. Coating advantage in different properties such as surface adhesion to sublayer and impact resistance are investigated using mechanical tests results. Hardness test results showed that sample hardness with dual fusion bond epoxy powder coating compared to samples with polyurethane and 3-layer polyethylene coatings is 14% and 40% higher، respectively. Impact and holiday test on three coating also showed an acceptable level of resistance to external factors. Performing cathodic disbondment test at ambient and high temperature showed that increasing temperature has a direct influence on increasing coatings disbondment radius. 4. 49 mm lowest disbondment radius was observed on 3-layer polyethylene coating due to its intrinsic nature and high thickness.