PETROLEUM RESEARCH
Year:2018 | Volume:28 | Issue:98 |Papers Count:15

In order to produce and develop hydrocarbon fields، understanding of the exact nature of the reservoirs is necessary. Various criteria have been taken into consideration in the zonation of reservoirs and reservoir intervals to separating net and non-pay intervals. Separating the reservoir based on rock type concept can fix the geological disadvantages of conventional zonation methods based on lithology or sedimentological facies. In this study، five rock types have been achieved in carbonate-evaporates of Kangan and Dalan formations from the standard Winland method with Winland’ s coefficients. Modified coefficients have been resulted in the determination of four rock types. Results have been showed that determining the rock types based on standard Winland method produces a huge error so that the pore sizes will be three times larger than the real values. Therefore، rock typing with new presented coefficients increases the precision of the calculations and better understanding of the reservoir nature. Integrating these data with thin section studies shows that dolomitization and dissolution are two important diagenetic processes that change reservoir properties in these determined rock types.

In this article، at first ZSM-5 zeolite using metakaolin as a source of alumina was synthesized by using a microwave oven. In this regard، ZSM-5 zeolites with high purity and in relatively short time (25 min with microwave irradiation) were successfully prepared. Then nano particle Fe-Cr/ZSM-5 zeolite composite catalysts were prepared via Solid State Dispersion (SSD) and encapsulation methods. Samples were prepared by mixing different weight ratios of Fe2O3، Cr2O3، and K2CO3 powders with ZSM-5 zeolites at the first method، and for the second one، the metal complexes were encapsulated within the ZSM-5 zeolite pores. Prepared catalysts then characterized via EDX، SEM، XRD and FT-IR techniques. The catalytic performance of the synthesized catalysts was evaluated in ethylbenzene dehydrogenation to styrene in the presence of steam at 610 ° C under atmospheric pressure. The results demonstrate that ZSM-5 oxide loaded catalysts have better performance than bare zeolite. And also samples with Fe2O3 nano particles act more effectively than Cr2O3 loaded zeolites. It was shown that styrene yield was significantly been influenced by loading Fe2O3، Cr2O3 and K2CO3 materials. The comparison between performance of SSD and encapsulation method was shown that the second one with smaller particle size and high Fe-Cr oxide dispersion has higher yield and conversion toward styrene production.

This study has been focused on the relationship between cementation and dissolution processes with depositional facies and unconformity surfaces of upper part of the Sarvak Formation (Cenomanian-Turonian and mid-Turonian unconformity surfaces)، using core and thin section data from a key well. Based on petrographic studies، six facies related to lagoon، slope and open marine sub-environments were identified. The results of this study indicate that the dissolution and cementation processes have been occurred in several diagenetic stages. Dissolution of unstable skeletal grains under the effect of eogenetic diagenesis created extensive vuggy porosity. In addition، during the telogenetic diagenesis and in relation to unconformity surfaces، vuggy pore types within the grains and rock matrix have been developed. The distribution of calcite cement within the reservoir shows a close relationship with initial mineralogy of the skeletal grains، size of dissolution vugs as well as density and the width of the factures. Calcite cement occurs as drusy and blocky forms and with meteoric and burial source within the dissolution vugs and microfractues. Within the Turonian interval that has been situated below the mid-Turonian unconformity، due to the mud-dominated nature of lagoon and open marine facies، dissolution and cementation have insignificant distribution، and calcite cement is mostly observed in relation to fractures. In contrast، in the interval below the Cenomanian-Turonian boundary، these processes have more distribution due to the frequency of grain-dominated facies. The results of this study show that the nature of depositional facies has significant role on distribution of cementation and dissolution processes within the Sarvak Formation.

Hydrodynamic and mass transfer simulations of toluene rising drops have been investigated. The VOF-PLIC method with surface tension model of CSS was applied. Drops have been simulated in the three regimes of spherical، circulating، and oscillating regimes. Simulation results agreed well with existing experimental data with the average relative error of 3. 63 percent. The current hydrodynamic model predicted the oscillating regime for the drop diameter of 4. 4 mm and 3. 5 mm drops were identified as the drops with maximum velocity. These findings agreed well with existing experimental data. In the next step of simulations، mass transfer equation was supplemented into the simulations investigating mass transfer effect on the velocity of 2 mm toluene drops. All of the properties of drops were assumed constant except surface tension coefficient. Simulation results showed that، with the assumption of concentration dependent surface tension coefficient، terminal velocity relative error was about 2 percent، while without considering of that، relative error increased to 83 percent. Streamlines، drop shapes، axial velocity، and terminal velocity were also reported.

Production optimization is one of the most complex activities from the operational point of view due to the effect of the uncertainty of physical rock and fluid properties، errors، and the lack of measurement tools. Production optimization is defined based on a set of activities that measure and collect data to make optimized management decisions. The purpose of this study is to optimize the production of a mature hydrocarbon field located in the south of Iran with consideration operational nonlinear constrains، and by defining four different scenarios. Cumulative oil production and net present value were used to select the best production scenario from this oil field. The results of simulation and optimization showed that in the current situation of the field، gas injection is prioritized with respect to artificial gas lift with gas due to the reduction of cost and time، as well as an increase in current net present value. Although، using an artificial gas lift method، the amount of cumulative oil production is higher than the gas injection method، but due to increased costs، it will have less net present value.

One of the most important sections in fulfilled study (FFS) and master development plan is history matching which plays an important role in production scenarios and future production plan of reservoir. It would be a challenge for reservoir engineering due to lots of parameters and uncertainties during reservoir study which need lots of simulation runs to reach good match for responses in conventional mechanism of history matching. However، for accelerating history matching part، new methods which called as assisted or automated history matching (AHM) have been established. In this paper، an approach for automated history matching (AHM) was applied in a real brown field with 14 wells with multiple responses located in south of Iran. The main important features of the proposed algorithm were defining a proxy model which was a response surface method in which 21 model parameters were incorporated based on cubic centered face method. Response surface method (RSM) has been employed to create the proxy model. The optimization algorithms utilized in this research were genetic algorithm (GA) and particle swarm optimization (PSO). Proxy model was successfully constructed using 256 samples leading into R2 of 0. 9 on dataset with good results on GA.

The current study employs an efficient approach in construction of 3D reservoir geomechanical models based on the concept of GMUs. Rock strength estimation using indirect methods plays an important role in reservoir characterization. Indirect methods are more cost-effective and efficient than direct methods. The elastic-dynamic moduli can be used to obtain rock strength data. In this study، the amount of data was reduced through using multiresolution graph-based clustering and geomechanical units (GMUs) were established based on MRGC-derived clusters. Construction of a 3D geomechanical model using these GMU’ s is a reliable approximation of reservoir characteristics from the rock strength point of view. The elastic-dynamic moduli such as Young’ s modulus، bulk modulus، shear modulus، Poisson’ s ratio and UCS of the formation were calculated using compressive and shear wave velocities which are provided by DSI logging tools in eight wells. In some of the wells، shear wave velocities are predicted through multivariable regressions. Results show that the correlation coefficient between measured and estimated shear velocity is approximately 90 percent. Afterward، the calculated dynamic moduli were calibrated to static values using empirical equations extracted from a neighboring field. All calculated static moduli were clustered by using multiresolution graph-based clustering (MRGC) method for all eight wells. Finally، a 3D geomechanical model of the reservoir was generated based on these geomechanical units and the reservoir acoustic impedance model as a secondary parameter of co-krigging. The reservoir acoustic impedance model was built by using a genetic algorithm and model based inversion. After establishing the GMUs by MRGC، the GMUs evaluated through correlating with the caliper، gamma ray and NPHI logs. There is a good correlation between the clusters and the log-derived properties in all wells. GMUs can be compared with lithology logs and core data as an alternative verification method. Results of this study show that mechanical properties of GMUs are strongly affected by the clay content and porosity of rocks. Also، the 3D geomechanical model has been generated from GMUs، and the reservoir acoustic impedance model shows a good degree of correlation confirming further confidence on the results of this study.

Determining the reservoir facies and areas with high-quality reservoirs play a pivotal role in reservoir modeling as well as future drilling in developing oilfields. As an index which varies in line with changes in the reservoir characteristics، Flow Zone Indicator (FZI) could be an influential factor in dividing the facies. The present study attempts to propose an advanced، optimized model through integrating the intelligent systems to estimate the FZI in the whole oilfield. This Committee Machine (CM) integrates the predicted results obtained from the intelligent neural، fuzzy logic، and Nero-Fuzzy systems with defined weights. Optimized weights for each method are determined using the Ant Colony Optimization Routing (ACOR) Algorithm. In this study، to apply the methods، well log and seismic data were used from one of the oilfields in South Iran. At the first stage، seismic attributes which were far more associated with the target data (FZI) were selected by stepwise regression. Subsequently، a 3D cube flow indicator in the whole field was estimated with intelligent systems. Finally، various reservoir facies were classified by the means of Fuzzy C-Mean Algorithm. The results illustrate that the committee machine which utilizes ACOR outperforms other individual systems acting alone.

Scarcity of water as well as shortage of water reservoirs is a major global issue excruciating by an increase in population. Saving water in irrigation is a vital solution in protecting water reservoirs and takes high priority among other possible solutions. Superabsorbents are cross-linked hydrophilic polymers with the ability to reversibly swell in water as well as absorbing high volume of water، thus superabsorbents have attractive application in agriculture. In this research، the effect of synthesis factors such as acrylamide and acrylic acid monomers، the amount of bentonite and the ratio of cross-linker to initiator on swelling behavior and water absorbency of hydrogel were investigated and their absorbtion and desorbtion in sour solution and soil was determined. Superabsorbents were synthesized by solution polymerization and their chemical structures were characterized by FTIR، SEM، XRD، TGA، and DSC. The results showed that an increase in cross-linker would decrease the equilibrium swelling، and by using the optimum of the initiator، an increase in acrylamide and acrylic acid، the equilibrium swelling would increase. An increase in bentonite would increase equilibrium swelling، but additional bentonite will decrease it. By optimizingmentioned additives، a superabsorbent was prepared with the water absorbency of 1125 g/g. The results of absorbtion and desorbtion of optimized superabsorbent in highly sour solutions and soil have showed that the synthesized superabsorbent is highly practical in sour solutions، thus suitable in highly sour soils.

The measurement and prediction of density is required for accurate assessment of the production rate of oil. In the present study، the impact of synergetic parameters (pressure، temperature، and fluid composition) on the density of asphaltenic synthetic oils and crude oil is investigated. Furthermore، within the range of operating condition for 546 experimental data of asphaltenic synthetic oils، a correlation is proposed for synthetic oil including toluene، normal heptane and asphaltene extracted from various crude oils. The comparison between the experimental data and the predicted densities showed that the proposed model accurately predicted the experimental data with correlation coefficients (R2) of more than 0. 97. The results also confirmed that the propensity of densities by changing various parameters are as follows. At a given temperature as pressure increases، density increased for crude and synthetic oils. Furthermore، for both types of attempted oils، at different pressures، an increase in temperature caused the reduction of the density. The impact of temperature was dominant in the range of 50 to 80 ° C. In addition، for asphaltenic synthetic oils، an increase in the concentration of asphaltene in the synthetic oils، especially from 5 to 10 wt. %، resulted in a significant increase in the oil density.

In this study، magnetic nanoparticle supported by guanidine was synthesized، and its property was investigated in adsorption of methylene blue from wastewater samples. Physical and structural characteristics of the adsorbent were investigated by SEM، TEM، and FTIR techniques. The effect of pH، initial concentration of methylene blue and adsorbent، contact time، and temperature were investigated to determine equilibrium isotherms، and kinetics of adsorption process. The optimum conditions of adsorbent were: pH=6، contact time=30min، adsorbent dose of 2. 5 g/L and room temperature. The equilibrium isotherm study showed that the adsorption process was fitted by Langmuir model and the adsorption kinetic a good compliance with pseudo second-order model. The present study showed that the magnetic nanoparticle supported by guanidine has high potential for adsorption of methylene blue، in addition to features like simple and rapid separation. Therefore، it can be used for adsorption and separation of such pollutants from aqueous solutions.

Based on the extensive studies which have been done، undoubtedly، the role of the wave velocity data of rocks in hydrocarbon reservoir evaluation is absolutely vital. Within، it is important to study the wave velocities in the Dolomites، which often make up one of the best parts of hydrocarbon reservoirs in the carbonate system. Certainly، the texture of rocks، mineralogical composition، grain size، percent of quartz in rocks، and many microstructure properties affect the Engineering and Physical Behavior of rocks. According with previous studies and to better understanding this relationship، a comprehensive program of tests on the three categories of dolomite with fine، medium and coarse grained were designed. In this paper، the results related to the measurement of compressive (Vp) and shear wave velocity (Vs) for 32 samples are given. According to the results، with increasing in grain size، density of rock decreases. The compressive and shear wave velocity for fine grain and coarse grain samples were found to be %9 and %12 lower، respectively، than those for the medium grain samples. The results showed that for fine، medium and coarse grain samples; moreover، the ratio of Vp/Vs is 1. 78، 1. 81، and 1. 77 respectively. It was also observed that the dynamic Young› s modulus for the medium grain samples approximately 15% of the fine grain samples and approximately 27% of the coarse grain samples is more. In addition، it was found that a significant change does not occur in Poisson› s ratio of the studied rocks with an increase in grain size.