Research Paper
Petroleum Engineering
Amir Gharavi; Mohamed Hassan; Hesam Zarehparvar Ghoochaninejad; John Fianu; Michael Kenomore; Amjad Shah; James Buick
Abstract
Since the development bloom in unconventional reservoirs in North America, total organic carbon (TOC) has become a more essential parameter, as the indicator of the efficiency of these reservoirs. In this paper, by using conventional well logs and NMR log data, the TOC content of an unconventional reservoir ...
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Since the development bloom in unconventional reservoirs in North America, total organic carbon (TOC) has become a more essential parameter, as the indicator of the efficiency of these reservoirs. In this paper, by using conventional well logs and NMR log data, the TOC content of an unconventional reservoir in West Africa is estimated. Passy’s, Issler’s, and Schmoker’s methods were used as indirect wireline methods to estimate TOC content, along the well paths. Afterward, NMR log data, as a direct method, was used to provide more precise calculations of TOC. Both methods showed almost similar trends, with the NMR method indicating lower values for the TOC. Then, an adjusted Schmoker equation was proposed, which showed the best fit between NMR and conventional well logs results. By using the equation, the TOC content was calculated in three other wells, where NMR data were unavailable. The results were then used to prepare a 3D model of the TOC distribution, within the reservoir.
Research Paper
Petroleum Engineering
Mehdi Qassamipour; Elnaz Khodapanah; Seyyed Alireza Tabatabaei-Nezhad
Abstract
Net pay thickness is defined as that portion of a reservoir which contains economically producible hydrocarbons with today’s technology, prices, and costs. This thickness is a key parameter of the volumetric calculation of in-place hydrocarbons, well test interpretation, and reservoir characterization. ...
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Net pay thickness is defined as that portion of a reservoir which contains economically producible hydrocarbons with today’s technology, prices, and costs. This thickness is a key parameter of the volumetric calculation of in-place hydrocarbons, well test interpretation, and reservoir characterization. A reservoir interval is considered as net pay when it contains hydrocarbons that can flow at an economic rate. Therefore, to define net pay, cutoffs of hydrocarbon storage properties besides flow properties of reservoir rock are necessary. Frequently, petrophysical log-derived rock storage properties like porosity and water saturation are linked to core measured properties like permeability to find a relation between them. Then, by use of a fixed limiting value for permeability, log-derived properties cutoffs are determined. The basic problem of these methods is related to permeability cutoff, since in most cases there is no knowledge about it, and the permeability cutoff can differ from field to field or even well to well. A new methodology has been developed to find a logical permeability cutoff for gas reservoirs which can differ for different wells and/or fields. This technique is based on gas flow through porous media in tight rocks. Accordingly, a relationship between porosity and permeability is derived as a cutoff value at reservoir pressure and temperature, which is considered as a discriminator plot. Then, the core data of the specified reservoir are added to this plot and the data points reflecting net pay zone are identified. This technique has been applied to four real gas reservoirs in Iran and indicated acceptable results confirmed by the drill stem test (DST) and production data. The results show that the proposed procedure is less dependent on experts’ experiences and acts as a straightforward and powerful tool for the refinement of net pays. In addition, the cutoff values calculated from this method contain a scientific base supporting the main procedure.
Research Paper
Electrical Engineering – Control
Mahdi Imanian; Mahdi Karbasian; Aazam Ghassemi
Abstract
Control of wellbore pressure during drilling operations has always been important in the oil industry as this can prevent the possibility of well blowout. The present research employs a combination of automatic process control and statistical process control for the first time for the identification, ...
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Control of wellbore pressure during drilling operations has always been important in the oil industry as this can prevent the possibility of well blowout. The present research employs a combination of automatic process control and statistical process control for the first time for the identification, monitoring, and control of both random and special causes in drilling operations. To this end, by using automatic process control, control charts are applied to the output of the controlled process; subsequently, the points which are outside the predefined control limits are identified. This method is capable of using controllable input variables not used in automatic process control, such as changes in the mud weight, to fully control the process. Due to the dynamic nature of the process, adaptive model-based controllers have replaced feedback methods in automatic process control. Control charts have also been used to compare the performance of different automatic process control approaches. Based on this new criterion, the fuzzy adaptive approach is shown to have good performance in automatic process control. The results indicate that this approach can improve the limits of the automatic process control method by using statistical process control for controlling the bit pressure in an acceptable range.
Research Paper
Petroleum Engineering
Amin Daryasafar; Mohammad FathiNasab; Giovanni Da Prat; Riyaz Kharrat
Abstract
In this paper, decline curve analysis is used for estimating different parameters of bounded naturally fractured reservoirs. This analysis technique is based on rate transient technique, and it is shown that if production rate is plotted against time on a semi-log graph, straight lines are obtained that ...
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In this paper, decline curve analysis is used for estimating different parameters of bounded naturally fractured reservoirs. This analysis technique is based on rate transient technique, and it is shown that if production rate is plotted against time on a semi-log graph, straight lines are obtained that can be used to determine important parameters of the closed fractured reservoirs. The equations are based on Warren and Root model. The comparison between the results of this technique and those of the conventional methods confirms its high proficiency in transient well testing. It should be noted that in conventional decline curve methods, parameters such as interporosity flow parameter and storage capacity ratio must be first obtained by previous methods like the build-up analysis, but in the proposed method all the main reservoir parameters can be calculated directly, which is one of the advantages of this method. This paper focuses on the interpretation of rate tests, and the starting points and slopes of straight lines are utilized with proper equations to solve directly for various properties. The main important aspect of the presented method is its accuracy since analytical solutions are used for calculating reservoir parameters.
Research Paper
Petroleum Engineering
Mohsen Seidmohammadi; Eghbal Sahraei; Behrouz Bayati
Abstract
Currently available polymers as a component of in-situ gels are unsuitable for treating high-temperature/high-salinity reservoirs due to their chemical and thermal degradation. In this study, a new copolymer-based gel system including high molecular weight nanostructured polymers (NSPs) was developed ...
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Currently available polymers as a component of in-situ gels are unsuitable for treating high-temperature/high-salinity reservoirs due to their chemical and thermal degradation. In this study, a new copolymer-based gel system including high molecular weight nanostructured polymers (NSPs) was developed to address the excessive water production problem in reservoirs under harsh conditions. The stability of conventional polymer systems and NSPs was investigated under conditions of 40 days aging at 87000 ppm salinity and 90 °C. Then, gelation time optimization of gel systems composed of NSPs and chromium (III) acetate was performed with regards to the effect of copolymer concentration and copolymer/cross-linker ratio and their interactions during the gelation time. The central composite approach was used to design experiments and build a mathematical model. The analysis of variance (ANOVA) was used to estimate the deviation of the model predictions from the data. The results of stability analysis demonstrated the advantages of NSPs over conventional polymers by a viscosity reduction of 69, 36, and 18% for Flopaam3310, AN105, and NSPs respectively. The model developed for the prediction of gelation time of NSPs gel was significant at a confidence level of 98.6% against the test data. Moreover, it was found that gelation time became longer with a decrease in copolymer concentrations and/or increase in copolymer/cross-linker ratio.
Research Paper
Chemical Engineering
Mohammadreza Khosravi-Nikou; Ahmad Shariati; Mohammad Mohammadian; Ali Barati; Adel Najafi-Marghmaleki
Abstract
This study presents a robust and rigorous method based on intelligent models, namely radial basis function networks optimized by particle swarm optimization (PSO-RBF), multilayer perceptron neural networks (MLP-NNs), and adaptive neuro-fuzzy inference system optimized by particle swarm optimization methods ...
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This study presents a robust and rigorous method based on intelligent models, namely radial basis function networks optimized by particle swarm optimization (PSO-RBF), multilayer perceptron neural networks (MLP-NNs), and adaptive neuro-fuzzy inference system optimized by particle swarm optimization methods (PSO-ANFIS), for predicting the equilibrium and kinetics of the adsorption of sulfur and nitrogen containing compounds from a liquid hydrocarbon model fuel on mesoporous materials. All the models were evaluated by the statistical and graphical methods. The predictions of the models were also compared with different kinetics and equilibrium models. The results showed that although all the models lead to accurate results, the PSO-ANFIS model represented the most reliable and dependable predictions with the correlation coefficient (R2) of 0.99992 and average absolute relative deviation (AARD) of 0.039%. The developed models are also able to predict the experimental data with better precision and reliability compared to literature models.
Research Paper
Technical Inspection Engineering
Zeinab Nassaj; Fatemeh Ravari; Iman Danaee
Abstract
In this paper, graphene oxide decorated with cerium oxide (CeO2) nanoparticles was prepared and used as anticorrosive pigments in epoxy nanocomposite coatings. The synthesized nanoparticle was characterized by FTIR, XRD, SEM, and EDX analyses. Graphene oxide decorated with CeO2 nanoparticles was dispersed ...
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In this paper, graphene oxide decorated with cerium oxide (CeO2) nanoparticles was prepared and used as anticorrosive pigments in epoxy nanocomposite coatings. The synthesized nanoparticle was characterized by FTIR, XRD, SEM, and EDX analyses. Graphene oxide decorated with CeO2 nanoparticles was dispersed in epoxy resin by sonication. The optimum nanoparticle content of the epoxy resin was studied by differential scanning calorimetry. The anticorrosive properties of these coatings were investigated using electrochemical impedance spectroscopy method and polarization in corrosive solution. Impedance parameters showed a decrease in the coating resistance over immersion time. The results indicated that the epoxy coatings containing nanoparticles could significantly increase the corrosion resistance of composite coatings compared to those of pure epoxy, and the highest value was obtained for 1% nanocomposite coatings after 270 days of immersion. Pull-off adhesion test showed that the highest value of adhesion was related to the coating containing 1% nanoparticles.
