International Journal of Oil, Gas and Coal Technology (48 papers in press)
CO2 Sequestration Potential in The Near-Future Depleted CO2 Reservoir: Dodan CO2 Field, Turkey
by Sukru Merey
Abstract: Dodan field is a natural CO2 reservoir located in Siirt, Turkey. Since 1986, CO2 produced from Dodan field have been injected into Bat? Raman Heavy Oil Field of Turkey in Batman to make heavy oil mobile in porous media. CO2 sequestration into aquifers and depleted reservoirs is widely investigated to decrease CO2 emission and to slow down global warning. In this study, it is aimed to investigate whether it is possible to inject CO2 into Dodan field after depletion. The source of CO2 to be injected might be supplied from cement factories near this field. CO2 injection into Dodan field was simulated by using TOUGH + RealGasBrine. According to the output results of these simulations, CO2 injection is much more difficult and slow processes compared to CO2 production. Due to water influx into the reservoirs in Dodan field during CO2 production, approximately 61.2 % of initial CO2 in-place (6.74 MMMSCM) might be injected into Dodan field in a long-term period.
Keywords: CO2 sequestration; CO2 flow; porous media; greenhouse emission; Dodan field.
Gas permeability evolution characteristics of limestone under different stress conditions
by Qiangxing Zhang, Jianfeng Liu, Zhide Wu, Lu Wang
Abstract: The increasing demand on energy storage has drawn worldwide attention on the construction of underground gas storage (UGS) project. As gas permeability is a key parameter in evaluating the sealing capacity of caprock in underground gas storage facilities, a comprehensive test on limestone concerning gas permeability and triaxial compression under different stress conditions was conducted using hydro-mechanical (HM) coupling testing platform in the laboratory. Also, the rock damage evolution of limestone during triaxial compression was monitored with an acoustic emission (AE) machine. Initial permeability of intact limestone ranges between 10?18 m2 and 10?16 m2 under different confining pressures, while permeability of fractured limestone is below 10?14 m2. Relationships between porosity vs. confining pressure and initial permeability vs. confining pressure are negative exponential, and both porosity and initial permeability decrease with increasing confining pressure. The permeability - axial strain curves of limestone show two different evolution laws under different confining pressures, which is highly related to the crack volume deformation characteristics. Spatial localization of AE events can accurately reflect the growth of internal cracks and explain the basic rules of permeability evolution.
Keywords: Limestone; Gas permeability; Acoustic emission; Caprock; UGS facilities.
Recent Advances of Cementing Technologies for Ultra-HTHP Formations
by Wenjun Cai, Jingen Deng, Ming Luo, Yongcun Feng, Jing Li, Qiang Liu
Abstract: Ultra-high-temperature-high-pressure (ultra-HTHP) formations are usually those formations having a temperature over 200
Keywords: ultra-HTHP; cementing; fluid loss; displacement efficiency; complex downhole conditions.
Injection of Gel Systems for CO2 Leakage Remediation in a Fractured Reservoir
by Peixi Zhu, Shayan Tavassoli, Jenny Ryu, Michael Pyrcz, Matthew Balhoff
Abstract: We perform a reservoir simulation study to investigate injection of gel systems, including crosslinked polymer gels and silica gels, as a treatment method for fracture sealing and leakage remediation in CO2 storage reservoirs. An adsorption and permeability reduction approach were adopted to model the fracture sealing by the gel. The results show that for both gel systems a successful treatment can reduce CO2 leakage by 103 times over 25 years of post-treatment CO2 injection. The effects of operating conditions, reservoir heterogeneity, and associated uncertainty on the treatment results were investigated by changing the injection time, injection rate, crosslinked polymer or silica concentration, reaction frequency factor, average reservoir permeability, and spatial correlation length. The simulation results show that selecting the appropriate operating conditions for specific reservoir properties are important to the success of CO2 leakage remediation.
Keywords: Gel treatment; CO2 sequestration; CO2 storage; leakage remediation; silica gel; crosslinked polymer gel; heterogeneity; Dykstra-Parsons coefficient; spatial uncertainty; reservoir simulation.
A novel model for predicting tight sandstone reservoir permeability
by Lili Sun, Xining Hao, Hong En Dou, Caspar Daniel Adenutsi, Wenli Liu
Abstract: In order to solve the problem of low accuracy of permeability prediction in tight sandstone reservoirs, two new parameters namely effective movable fluid saturation and capillary-bound fluid saturation were proposed, to quantitatively evaluate the flow capacity of reservoir fluids based on the analysis of the state of fluid occurrence in pore space. Nuclear Magnetic Resonance (NMR) and high-pressure mercury injection experiments were used to establish the relationships between permeability and the new parameters and a new permeability prediction model was proposed in tight sandstone reservoirs. The method was verified by comparing permeability computed using existing models and measured data from the field. The results showed that the proposed model in this paper gave R2 and root mean square error values of 0.839 and 0.0428, respectively, which were better than that given by the SDR and the Coates models. Thus, the proposed model in this research significantly improved the accuracy of permeability prediction in tight sandstone reservoirs. This provides a new method for permeability prediction and field development in tight sandstone reservoirs.
Keywords: effective movable fluid saturation; capillary-bound fluid saturation; permeability; tight sandstone reservoir; nuclear magnetic resonance; T2 cutoff.
Experimental investigation on enhanced oil recovery by multi-thermal fluid in mid-deep heavy oil reservoirs
by Cheng Wang, Liguo Zhong
Abstract: Multi-thermal fluid mainly consists of steam, N2 and CO2 and is a new heat-carrier introduced into the petroleum reservoir development in recent years. Multi-thermal fluid is more suitable for the development of mid-deep heavy oil reservoirs. In this paper, the PVT tests under different conditions were carried out to research the properties of heavy oil-CO2/N2 system. Then, a series of 3D simulation experiments were conducted, including steam flooding simulation experiment, multi-thermal fluid flooding simulation experiments and steam flooding to multi thermal fluid flooding simulation experiments, to analyze the production characteristics of multi-thermal fluid flooding and optimize the gas-water ratio of multi-thermal fluid flooding. Finally, the best way to develop mid-deep heavy oil reservoirs was investigate, according to the production characteristics of steam flooding and multi-thermal fluid flooding. This study provided a feasible way to development mid-deep heavy oil reservoirs with multi-thermal fluid.
Keywords: Multi-thermal fluid; Mid-deep heavy oil reservoir; Experimental investigation; Parameter optimization; PVT test.
CO2 Capture Analysis in Different Combustion Methods for CO2 Utilization and Storage
by Weijia Huang
Abstract: The high energy consumption of CO2 capture is the main issue of the application of CO2 capture, utilization and storage, new CO2 capture methods based on oxy-fuel combustion and chemical looping combustion are receiving considerable attention. However, the energy consumption performance of these methods is rarely compared when they are used as the CO2 source for CO2 utilization and storage. This work analyzed both the new developing and traditional methods of CO2 capture process to obtain their energy consumption performances. The CO2 capture processes of the oxy-fuel combustion and chemical looping combustion were respectively built and simulated under pressure varied from 0.1 MPa to 8.0 MPa. The captured CO2 product of each process was set to the same level of parameters for transportation, and a calculation method was developed to convert all types of energy consumption to equivalent power consumption. The results show that both the new CO2 capture methods have notable potential of low energy consumption, especially under higher combustion pressures. If the air separation process is considered, the oxy-fuel combustion CO2 capture requires further technical development to defeat the post-combustion CO2 capture, although it has the advantage of high CO2 concentration. The impacts of pressures of inlet gas and process sequence are analyzed to be the key reasons for energy performance.
Keywords: pressurized oxy-fuel combustion; chemical looping combustion; process simulation; energy consumption; CO2 capture.
Experimental study on risk analysis of gas explosion in a steeply inclined longwall gob: A case study of Dongxia Colliery
by Hetao Su, Yunzhuo Li, Yingke Liu, Xiaolin Song, Jiang Lv
Abstract: An explosive concentration can occur during mining due to the irregularity of methane emission and ventilation processes in the working face, making the explosion risk uncontrollable. This paper aimed at characterizing the gas explosion risk in a steeply inclined longwall gob (52
Keywords: airflow direction; ventilation velocity; oxygen concentration; methane migration; explosion risk.
Research on the Preparation of Coal Water Slurry with High Chloride and Concentrated Brine
by Chang-Ji Wang, Han-Xu Li
Abstract: In this paper, we focused on the simulation of high-salinity waste water to determine the effects of Cl- on the performance of coal water slurry.We found a feasible method for brine pulping and acquired an effective way to use the acquired brine. In this paper, NaCl and anhydrous CaCl2 were mixed with deionized water and used to configure the brine. The effects of the simulated brine with a different concentration on the slurry properties of the sample were investigated. The feasibility of the preparation of the coal water slurry for coal gasification with high-concentration brine was demonstrated by comparing the data with the actual high concentration brine. The experiment showed that highly concentrated salt water was used to replace the pulping water; the slurry concentration, the viscosity, the melting characteristic, and the stability, and the industrial pulping requirements were achieved. This technology had an increasing application and popularization.
Keywords: high-salinity waste water; slurrying.
Evaluation of tight sandstone reservoir in Es4 member of Yi176, Bonan Oilfield, China
by Meiling Jiang, Yunfeng Zhang, Yang Liu
Abstract: The Yi-176 block is located in the Yi-176 Boshen-4 fault step zone of the Bonan oilfield in the south of the Bonan sag. The Es4 member is considered as the target interval for this study. This interval was subjected to strong late diagenetic transformation, leading to irregular development of reservoir pore throats, hence, a strong reservoir heterogeneity. Therefore, a systematic study of reservoir microscopic characteristics is carried out, through core observation, casting thin slices, scanning electron microscope and high-pressure mercury intrusion in order to study the structure and type of conventional pores and nano-micrometer pores in the member and to determine the petrological and structural characteristics of the reservoir in the study area. Specifically, the characteristics and configuration relationship of reservoir pore throat are studied to determine the pore types, throat types, and fracture types. Consequently, sedimentation and diagenesis are identified as the main controlling factors of the reservoir quality. Moreover, using mercury intrusion test parameters, the reservoir types in the study area are divided into four categories through cluster analysis, followed by prediction of the planar distribution of different types of reservoirs. The results show that the development of Type I reservoirs is relatively mature, while, is Type II and Type III reservoirs are considered as the main exploration and development direction in the future.
Keywords: reservoir heterogeneity; reservoir microstructure; main controlling factors; reservoir types; the planar distribution.
Comprehensive evaluation of water utilization during shale gas exploration and exploitation in China
by Cong Dong, Xiucheng Dong, Congyu Zhao, Qingzhe Jiang
Abstract: This study comprehensively evaluates the impact of shale gas exploration and exploitation on water utilization from the perspective of geological heterogeneity in China. With the application of a process-based life cycle inventory (LCI) model, we quantitatively analyze the water environment in three major shale gas regions in China and calculate the specific and detailed consumption of local water resources during shale gas extraction in the Changning-Weiyuan, Fuling and Yanchang areas. The results show that the water consumption amount during shale gas extraction in the Changning-Weiyuan area is 21594.26 m3, which is smaller than the amount of 28105.94 m3 in the Fuling area, and the water consumption amount during shale gas extraction in the Yanchang area is estimated to be between the consumption amounts in the above two areas, at approximately 25000 m3. The water shortage in these three regions under the impact of shale gas extraction is then further measured by the water supply and demand index. Comparison reveals that the Changning-Weiyuan region contains the most abundant water resources, and Yanchang is confronted with water scarcity during shale gas development. Considering that the water demand during shale gas extraction is high, these conclusions provide a reference for the sustainable development of shale gas projects in China.
Keywords: shale gas; water utilization; geological heterogeneity; LCI; China.
Theoretical and experimental study on identification of the soft interlayer in coal mine roadway roof
by Guangdong Yu, Guoying Meng, Xuewen Feng, Binglin Song, Shuaishuai Shang, Yuhang He
Abstract: To identify the weak interlayer in roofs during the coal mine roadways support process and prevent roof-related accidents, this study proposes a soft interlayer roof detection system for mine roadways while drilling, whose drilling parameters can be detected using a pneumatic bolt machine, sensor and controller. The torque and speed of the pneumatic motor and the pressure and speed of the leg cylinder were used to detect the soft interlayer in the roadway roof. The calculation formula of the drilling parameters of the roof rock was derived and the effectiveness of the system is verified by finite element simulation. A test system for the roof rock formation identification system was developed and the identification test data were
compared with the rock uniaxial compressive strength test data. The proposed system has three advantages: the roof rock layer interface (weak interlayer) can be identified; owing to the installation of the pneumatic electric proportional valve and controller, unmanned operations can be performed by the functions present in the computer control system; and by testing the drilling parameters of the pneumatic bolt rig system, the strength and position of each rock layer of the roof can be calculated.
Keywords: roof rock stratum; pneumatic; MSE of rock fragmentation; weak interlayer.
Technical research and Engineering demonstration of "Coal to Electricity" in villages and towns in China
by Qian Miao, Dong Qing You
Abstract: The environmental pollution has become increasingly serious, since energy consumption, especially coal and other fossil energy increase dramatically in China. It is an urgent task for our country to deepen air pollution control, and construct an overall economic, safe and clean energy supply system. The electricity heating, compared with traditional coal-fired heating, has benefits, including high thermal efficiency, high degree of automation, safety and reliability, and flexible operation modes. Furthermore, electricity heating is zero emission, which doesnt produce dust, waste residue, exhaust gas or any other pollutant, as a significant means to solve the haze. China is strongly advocating and promoting the electricity heating (transform heating from coal to electricity) project in order to give full play to electric energys convenient, safe, clean, efficient and other advantages. Provided that an electricity heating project is combined with the utilization of wind curtailment and other resources during off peak hours at night, it can improve the absorptive proportion of clean energy, reduce effectively the load difference between peak and valley of power grid, increase the utilization efficiency of power generating equipment, and cut the cost, etc. The paper introduces State Grids first centralized demonstration project of coalto-electricity, and expounds in detail the project implementation program, operation effect, necessary supporting policy mechanism for future projects. The paper aims to guide the whole society to raise awareness of environmental protection, change consumption concept of energy, and provide a reference for air pollutions prevention and control in our country based on the successful experience of demonstration project.
Keywords: electricity heating; absorption of wind curtailment; electric boiler; energy storage technology; large consumer’s direct trading.
Application of stability analysis in surrounding rock control and support model of deep roadway
by Jianfeng Cui, Weijun Wang, Chao Yuan
Abstract: At present, there are more than 30 state-owned key coal mines with a mining depth of 1,000 m, and the maximum mining depth is close to 1,500 m, which is increasing at the rate of 812 m depth extension every year. In order to realise the sustainable development of the coal industry, the deep mining has become an important issue that the coal industry must solve. Before the exploitation of underground coal resources, the coal and rock mass are in the original stress state. After the mining activities, the original stress balance state of the coal and rock mass is destroyed, resulting in stress concentration, stress transfer and other stress changes, forming mining stress field around the mining space. It is the change of stress in the coal and rock mass that causes the deformation of surrounding rock, the movement of rock strata and the instability of structure, which leads to the occurrence of various disasters. [Received: 7 July 2020; Accepted: 5 February 2021]
Keywords: deep roadway; original rock stress; stress concentration; stress transfer; stability.
Mapping urban form and land use with deep learning techniques: a case study of Dongguan City, China
by Feihao Chen, Jin Yeu Tsou
Abstract: Precise urban form and land use data are crucial for various modeling simulations. Approaches using spectral features of remote sensing (RS) images have been widely adopted to capture land surface patterns. However, challenges arise concerning the accurate classification of built areas due to high levels of heterogeneity. An effective way to address this issue is to incorporate spatial contextual information. Deep learning techniques have recently been applied to RS image classification, and impressive results have been reported. This research undertook a case study of Dongguan City, which is a core Chinese city characterised by high density and heterogeneity. A culturally neutral classification scheme called local climate zone was adopted for land surface classification. The default random forest classification was used as a benchmark, and the moving window approach and several pretrained convolutional neural network (CNN) models were also applied for comparison. The moving window approach achieved the highest mapping accuracy with a window size of 5 x 5. Although the CNN models failed to achieve state-of-the-art results, they still exhibited an excellent performance considering the small number of input features and small input patch size. They can also reduce the salt-and-pepper phenomenon effectively. [Received: October 23, 2020; Accepted: January 24, 2021]
Keywords: deep learning; convolutional neural network; CNN; land use/land cover; classification; local climate zone; LCZ; China.
Prediction of Vapor-Liquid Equilibrium Ratios for the CH4-CO2-H2S Systems Using Artificial Neural Networks
by Alireza Shams
Abstract: Acid gas removal is an important part of natural gas processing which is designed based on the type and concentration of impurities and the final specifications for the outlet gas. The typical process for removing acid gases involves their absorption from natural gas into a regenerative solvent. The efficiency of this process is affected by the mass transfer process between gas and liquid phases; so, it is necessary to study the phase equilibrium encountered in acid gas mixtures at different pressure and temperatures. In this work, an artificial neural network (ANN) has been developed to predict the vapor-liquid equilibrium ratio (KLV) for the CH4-CO2-H2S binary and ternary systems. Results show that a neural-network-based method provides an accurate estimation (93-98%) of KLV while considering all affecting parameters, compared to limited reported correlations. This work can be considered as an introduction to using ANNs for predicting the physical properties of mixtures.
Keywords: Natural gas processing; Equilibrium; Artificial Neural Network; Prediction.
Obtaining biodiesel from seeds of Ricinus communis: methodological proposal.
by Manuel Flota-Bañuelos, Carlos Victoria-Graniel, Liliana San-Pedro, Emanuel Hernández-Núñez, Luis Díaz-Ballote, Laura Paniagua-Solar, Carlos Victoria-Pérez, Nallely Téllez-Méndez
Abstract: In the present research it was studied the obtaining of biodiesel by transesterification of vegetable oil contained in the wild seeds of Ricinus communis, using methanol in the presence of sodium hydroxide as a catalyst, varying the oil/methanol ratios in the reactor of transesterification. To determine the possibility of using biodiesel as a fuel in internal combustion engines, the final product was characterized according to the criteria specified by the American Society for Testing and Materials (ASTM) and the European Organization Standardization (EN), in ASTM D6751 and EN 14214, respectively. The results indicate that the 1:9 molar ratio is the most efficient, the biodiesel obtained meets most of the parameters established by the ASTM and the EN. Thus, the methodology proposed to produce biodiesel from ricino seeds is feasible, since the final biodiesel presents favorable characteristics for its use as an alternative biofuel.
Keywords: biodiesel; methoxid; Ricinus communis; transesterification; methodology; biofuel; oil; seeds; catalysis; cold extrusion.
Influence of Coal Mechanical Properties and Water Content on Generation Characteristics of Coal Particles
by Yingchun Wei, Maolin Cui, Zheng Yao, Anmin Wang, Baolei Cui, Zhejun Pan
Abstract: Coal particles have a great importance in the production of coalbed methane. To reveal the relationship between the coal mechanical properties and the coal particles characteristics generated by the coal samples with different coal rank, coal failure experiments in the natural state and water-saturated state under triaxial compression are performed. The characteristics of coal particles from these different experiments are then analyzed. The effects of coal rank, coal mechanical properties and water content on the characteristics of coal particles generated are investigated. The results show that the water-saturated sample has a lower compressive strength than the corresponding natural sample. As coal rank increases, the compressive strength increases first and then decreases. The bituminous A (meager coal) has the highest compressive strength. Coal with different rank shows various fracturing modes after failure. Compared with the natural sample, the water-saturated sample generates more amount of coal particles. As coal rank increases, the amount of coal particles shows a U shape trend, while there is a negative exponential correlation between the amount of coal particles and the compressive strength of coal. The vitrinite content of the coal particles generated by the water-saturated sample is less than that generated by the natural sample, but more than the vitrinite content in the original coal sample.
Keywords: Coalbed methane; Coal particles; Mechanical properties; Water Content.
Evaluation of Ionanofluid for Chemical-Enhanced Oil Recovery for Matured Crude Oil Reservoirs
by Ankit Sharma, Abhijit Kakati, Sivabalan Sakthivel, Prashant Jadhawar, Jitendra Sangwai
Abstract: Interest on smart fluids are growing rapidly in different domains of petroleum industry owing to their unique properties and environmental safety. One such smartfluid which has not yet been explored for oil industry applications is ionanofluid. The purpose of present work is to evaluate applicability of ionanofluids for enhanced oil recovery (EOR) applications. Two different ionanofluids has been prepared for this study by adding silica nanoparticles into two different ionic liquids (tripropyl ammonium sulfate and triethyl ammonium sulfate) solutions. The effect of nanoparticle and ionic liquid on the interfacial tension of crude oil-nanofluid and their enhanced oil recovery performances have been evaluated. Ionanofluids has the ability to reduce the interfacial tension to a significantly low value. Results indicates that ionanofluids has much higher enhanced oil recovery efficiencies in comparison to nanofluid and ionic liquid alone. Therefore, ionic liquids has the potential to be used as an excellent future EOR agent.
Keywords: Enhanced Oil Recovery; Interfacial Tension; Ionic liquid; Ionanofluid; Nanofluid.
Estimation of heat capacities of amine-based solvents for CO2 absorption process using ANFIS model
by Ali Jalali, Marzieh Lotfi, Amir H. Mohammadi
Abstract: In this investigation, the Adaptive Network Based Fuzzy Inference System (ANFIS) has been successfully developed as a method of predicting the heat capacity (Cp) of certain amine-based solvents, using concentration of the solvent, system temperature, and an apparent molecular weight as input parameters. To reach a modelling system, 1253 and 278 experimental data points were extracted from the studies for binary and ternary systems respectively, and were afterwards separated into training and testing subdivision. Model coefficients were predicted using the training sets, and model validation was achieved in every system through the use of the mentioned testing sets. Comparing of the model result with experimental amount was done by investigating the some statistical parameters like mean square deviation (MSD), , R squared (R2) and average relative deviation (ARD) for assessing the ability and veracity of the developed model. The developed models ARD for binary and ternary systems are -0.937% and -0.036% respectively. Model show a great validation with experimental data, especially for a ternary system. Furthermore, the effects of temperature on Cp values of conventional amines at different concentrations were investigated. Outcomes revealed that the developed ANFIS model could be applied as a practical method in simulation of CO2 removal processes by amine based solvent for both mentioned systems.
Keywords: CO2 capture; ANFIS model; Heat capacity; Amine - based solvents; Prediction.
Effect of headspace air conditions on total organic acids dissolved in transformer oil
by Kobra Pourabdollah
Abstract: The aim of this work was studying the effect of dissolved oxygen concentration, temperature and humidity level of headspace air on the acidification of insulation oil. The novelty is assessment and classification of those parameters based on the acidity level, induction time and the rate of oil acidifying. Two gas-washers containing insulation oil and deionised water were in contact with the bubbling streams of O2/N2 containing different humidity levels. The acidity of two phases was determined based on TAN number and pH values, respectively. The results revealed that O2/N2 weight ratio, insulator temperature and the level of air humidity control the acidity strength, the induction time of acid production and the rate of oil acidifying, respectively. Reduction of O2/N2 weight ratio in the headspace air decreased the level of the produced organic acids, while reduction of temperature extended the onset time of acid formation. [Received: July 31, 2020; Accepted: January 12, 2021]
Keywords: dissolved gas analysis; DGA; oxidation; organic acid; insulation oil; humidity.
Geomechanical modelling using artificial neural networks combined with geostatistics
by Pham Son Tung
Abstract: The principal minimum horizontal stress (Shmin) plays an important role in reservoir simulation. Experimental formulas were established to determine Shmin along the wellbore. These formulas must be calibrated with LOT data whose number is usually limited or even sometimes unavailable. However, the empirical formulas of one field might not be accurate for others. This study presents a new approach to solve the problem of Shmin estimation by a combination of artificial intelligence and geostatistics. The method consists of using artificial neural network to build a model of Shmin estimation from relevant parameters such as true vertical depth, pore pressure and vertical stress, then combined with Kriging interpolation to obtain the distribution in space of Shmin. Hence, this method can estimate the minimum horizontal stress with a limited amount of available data and therefore we do not need to drill new wells or to find empirical formulas for each survey area.
Keywords: artificial neural network; ANN; geostatistics; logging; minimum horizontal stress; geomechanic.
A novel semi-analytical model for oil-water two-phase flow of a fractured vertical well in triple media carbonate reservoir
by Yong Wang, Xin Ma, Wenqing Wu, Zonghong Feng
Abstract: Carbonate reservoir is one of the important reservoir in the world. Because of the characteristics of carbonate reservoir, vertical well and acid fracturing has become a key technology for efficiently developing carbonate reservoir. Establishing corresponding mathematical models and analysing transient pressure behaviours of this type of well-reservoir configuration can provide a better understanding of fluid flow patterns in formation as well as estimations of important parameters. A mathematical model for a oil-water two-phase flow fractured vertical well in triple media carbonate reservoir by conceptualising vugs as spherical shapes is presented in this article. A
semi-analytical solution is obtained in the Laplace domain by using source function theory, Laplace transformation and superposition principle. Analysis of transient pressure responses indicates that several characteristic flow periods of fractured vertical wells in triple media carbonate reservoir can be identified. Parametric analysis shows that water saturation of matrix, vug and fracture system and half-length can significantly influence the transient pressure responses of fractured vertical wells in triple media carbonate reservoir. The model presented in this article can be applied to obtain important parameters pertinent to reservoir or fracture by type curve matching, and it can also provide useful information for optimising fracture parameters. [Received: May 18, 2019; Accepted: May 6, 2021]
Keywords: acid fracture; oil-water two-phase flow; fractured vertical well; transient pressure analysis; triple media carbonate reservoir.
Free volume vacancy behaviour and dynamic viscosity of diesel fuels with additives at elevated temperature and pressure: thermo-occupancy function
by Fatma SAHIN-DINC, Carl SCHASCHKE, Ugur YAHSI
Abstract: The reported pressure-volume-temperature (PVT) data of five different diesel fuels at T=297.95-373.06 K and P=0.1-457.2 MPa were described by the Simha-Somcynsky (SS) equation of state (eos). From the equilibrium condition imposed on the eos, the hole fraction, h=h(P,T), a form of free volume measure, was computed. Furthermore, our physically-based correlation implicating the thermo-occupancy function, Yh=Yh(h,T), in terms of a function of h=h(P,T) and T has been extended in this study to estimate the dynamic viscosity, for the mixtures of commercially available fuels. The model bridges a direct relation from an equilibrium property, h, to the transport process of the system and predicts the viscosity with the range from 0.15% to 0.31%. Newly designates "viscoholibility" function defined as the derivative of logarithm of viscosity with respect to hole fraction has been discussed. It has an exponential decaying behavior with respect to h.
Keywords: additives; diesel fuels; dynamic viscosity; free volume; Simha Somcynsky; thermo-occupancy function.
NiW/USY-?-Al2O3 modified by P, Zr and Mn for hydrogenation of coal tar to clean fuel
by Zegang Qiu, Shaobo Ma, Zenghui Zhang, Zhiqin Li, Liang Ding, Liangfu Zhao
Abstract: NiW/USY-?-Al2O3 catalysts modified by P, Zr and Mn were prepared by incipient wetness co-impregnation method. The addition of P significantly elevated the acid strength and the content of medium-strong acids, while the addition of Zr decreased the content of the medium-strong acids. The addition of Mn almost did not change the acidity of the catalyst. All catalysts were evaluated by using the diesel fraction from the hydrotreated coal tar and the naphthalene as feedstock. P, Mn and Zr modification all improved the overall hydrocracking activity of catalysts. The catalytic activity of P-NiW/USY-?-Al2O3 and Mn-NiW/USY-?-Al2O3 for hydrocracking of polycyclic aromatic hydrocarbons was higher than that of NiW/USY-?-Al2O3 and Zr-NiW/USY-?-Al2O3. Disparate hydrogenation or cracking activity of modified catalysts was observed. [Received: 04 August 2020; Accepted: 6 January 2021]
Keywords: coal tar; catalyst; hydrocracking; hydrogenation; alumina; clean fuel; nickel; tungsten; Y-zeolite; modification.
Numerical study on the influence of coal-roof interface on vertical propagation of hydraulic fracture
by Haozhe Li, Qun Zhang, Zaibing Jiang, Yaobo Xu, Jia Liu
Abstract: To extract coalbed methane (CBM) from tectonically deformed coal seams, a horizontal well was drilled in the roof of coal seam. Staged hydraulic fracturing was then conducted to connect the horizontal wellbore and underlying coal seam. A finite element model that coupled seepage, stress, and damage theories was built to investigate the influence of coal-roof interface on vertical propagation of hydraulic fracture. Results showed that the coefficient of friction and crossing stress ratio were the two primary factors controlling the fracture penetration. A higher interfacial shear strength is beneficial to fracture penetration. The crossing stress ratio required for fracture penetration decreases as the interface friction coefficient increases. The numerical simulation results agree well with the field pilot test and can provide theoretical support for effective CBM development in similar coal seams. [Received: October 28, 2020; Accepted: March 10, 2021]
Keywords: coalbed methane; CBM; numerical simulation; cohesive zone method; CZM; fracture propagation; coal-roof interface.
An experimental study of the hydrate formation and blockage in the partially dispersed system
by Shuyu Song, Guozheng Zhao, Zhiming Liu, Liyan Shang, Zhenbo Lv
Abstract: Hydrates in partially dispersed system can easily form in pipelines and cause blockages. Therefore, the formation and blockage characteristics of hydrates under different pressures and temperatures were studied through a high-pressure circulation pipeline. The results showed that the induction time and plugging time decrease as the initial pressure increases. An increase in the flow rate will prolong the induction period and plugging time. A free water layer appears at the bottom of pipeline before hydrate formation, and water films are formed on the inner wall of pipeline. When hydrate formation conditions are reached, the water films will transform into hydrate films, and hydrate particles will also generate inside the fluid. The initially formed hydrate will cause the free water layer to disappear. With the aggregation of hydrate particles and the thickening of the hydrate film, the circulation area of the pipeline decrease, which eventually cause plugging. [Received: October 14 2020; Accepted: March 14 2021]
Keywords: hydrate; initial pressure; flow rate; induction time; flow loop.
The influence of atmospheric pressure on methane drainage from mines in the Upper Silesian Coal Basin
by Pavel Zapletal, Grzegorz Pach, Maciej Kosowski
Abstract: This article presents the impact of various factors on the parameters of gas drainage using a methane drainage station. This problem has been poorly researched so far; the widest presentation was offered in the article by Myszor (1972). We decided to investigate the mutual correlations of gas drainage factors and parameters. Having measured the atmospheric pressure and the composition of mine gas at two mines, Pniowek in Poland and Paskov in the Czech Republic, correlations were found between individual parameters. The measurements were obtained using an automatic chromatograph NGC8200 and the INMAT 66 system. Based on the research results, we found that the atmospheric pressure on the surface of the mine had the greatest impact on drainage gas, which allows us to conclude that it is possible to create a computer model enabling the prediction of methane drainage station operating parameters. Thus, it will be possible to predict the quality and quantity of mine gas, based on which the entire energy system and cooperation of individual
sources will be effectively managed. [Received: 13 August 2020; Accepted: 22
Keywords: hard coal; methane; methane concentration; atmospheric pressure; methane drainage.
Productivity improvement with use of beam gas compressor: pilot test in Southeastern Europe mature field
by Bojan Martinovic, Dusan Danilovic, Branko Grubac, Robert Fadiga
Abstract: Most of the wells in the oilfield Turija are operating with sucker rod pumps, where casing pressure at around 15 bar, and with marginal production rates. The high value of casing pressure indicates high pressure on the face of the formation and depends directly on well productivity. In addition, with increasing value of the casing pressure gas column in the annulus is moving dynamic fluid level near pump intake and more gas is entering the pump, which results in decreasing pump efficiency. Reduced pump efficiency has a big impact on pump failure resulting in increased lifting costs. The beam gas compressor sucks the gas from the casing and boosts it into the flowline. Backpressure is relieved and allows more hydrocarbons to flow into the well. Based on study, industry known technology is once more proven as a reliable technology for solving casing gas problem and increasing productivity of the oil field. [Received: March 26, 2021; Accepted: May 12, 2021]
Keywords: beam gas compressor; BGC; increase productivity; sucker rod pump; SRP; mature field; artificial lift; production optimisation.
Integrated optimisation of multiple reservoirs in shared production systems
by João Carlos Von Hohendorff Filho, Denis José Schiozer
Abstract: The main objective of this study is to present efficient methodologies of integrated optimisation to achieve an optimised water injection scheme for the sandstone and carbonate reservoirs, both sharing the same platform. In the A methodology, the integration takes place in an intermediate stage of the assisted optimisation process. In the B methodology, the integration takes place in all stages of the optimisation. The two assisted methodologies proposed to optimise the production system were efficient in reaching the final production strategy and achieved an optimised production strategy in relation to the number and positioning of wells, at different total times. We found significant difference in production forecasting but similar results in the production strategy and the NPV of the optimised project, which
highlights the importance of its incorporation into the optimisation processes. However, we have also shown that the integration can be efficiently included in an intermediate stage of the optimisation. [Received: March 3, 2021; Accepted: April 27, 2021]
Keywords: reservoir; production system; multiple reservoirs; integration; simulation; project development; management; sandstone; carbonate; waterflooding.
Applicability of cogeneration system in gas turbines used in natural gas storage facilities
by Samet Türkoğlu, Ali Yurddaş, Abdulkadir Bektaş
Abstract: Underground natural gas storage facilities are of critical importance on energy supply security. Storage activity in facilities performing underground storage is mostly carried out in spent natural reservoirs. In this study, the applicability of cogeneration system was investigated in order to generate electricity from flue gas at an average temperature of 500 C and 144.4 t/h flow rate obtained from three gas turbines in storage facilities and to recover the waste heat we lost. This designed system would have three HRSGs and one steam turbine, 16.23 MW energy would be generated from each HRSG in this system. After a total of 48.70 MW energy, obtained from two HGRSs, enters into the steam turbine operating in 24% efficiency, 12.20 MW mechanic energy and 11.84 MW electric energy is generated. Therefore, a total of
97.05 MW energy entering into combined cycle power plant was transformed into a total of 42.25 MW useful energy, including 30.41 MW mechanical and 11.84 MW electricity, and the efficiency of system was calculated as 43.5%. It was aimed that the electric energy to be generated from this cogeneration system would contribute to the related facility and the electricity supply of the public against its price. [Received: 17 October 2020; Accepted: 03 May 2021]
Keywords: cogeneration; heat recovery steam generator; HRSG; gas turbine; steam turbine; energy efficiency; natural gas storage facilities.
Machine learning based estimated ultimate recovery prediction and sweet spot evaluation of shale oil
by Lufeng Zhan, Junwen Hu, Shaoyong Wang, Kun Wang, Bincheng Guo, Xuan Yang
Abstract: In this paper, we propose a machine learning-based, multi-discipline integrated evaluation workflow to evaluate sweet spots. We predict the estimated ultimate recovery (EUR) map and evaluate sweet spots at different oil price scenarios in the study area. The results show that the correlation coefficient between well EUR and predicted EUR is 0.9247. At the oil price of $40, $50, and $60/bbl, the sweet spot areas are 3.31 km2 , 27.75 km2, and 51.61 km2, and the total economically recoverable reserves are estimated to be 2.46 x 10 5 t, 14.02 x 10 5 t, 26.91 x 10 5 t respectively. It is concluded that machine learning model is an excellent way to auto learn the relationship between complex shale reservoir variables with EUR. It is innovative to show the distribution of sweet spots according to oil price. This workflow can be wildly used in the shale oil exploration and development to evaluate investments and optimise well placement. [Received: August 26, 2020; Accepted: April 19, 2021]
Keywords: shale oil; sweet spot; machine learning; discounted cash flow; DCF; estimated ultimate recovery; estimated ultimate recovery; EUR; prediction; visualisation.
Evaluation of crude slate and processing of recycle effects on H-Oil performance
by Dicho Stratiev, Ivelina Shishkova, Rosen Dinkov, Vassia Atanassova, Simeon Ribagin, Danail D. Stratiev, Krassimir Atanassov
Abstract: The LUKOIL Neftohim Burgas (LNB) H-Oil hydrocracker performance at different operating conditions, and different crude oils, and processing of recycle of partially blended fuel oil (PBFO) was assessed. The lower throughput, a result from the Covid 19 pandemic, allowed the LNB H-Oil hydrocracker to operate at a capacity lower than 50% of the design and to process recycle of PBFO achieving a vacuum residue conversion of 93%. The impact of crude oil slate, and processing of recycle of PBFO on conversion and on the unconverted hydrocracked vacuum residue quality was discussed. Intercriteria analysis was employed to evaluate the statistically meaningful relations of the operating conditions to the H-Oil conversion and yields. Regression equations were developed and discussed. [Received: April 16, 2021; Accepted: 28, 2021]
Keywords: ebullated bed vacuum residue hydrocracking; conversion; yields; asphaltenes; intercriteria analysis; correlations.
Classification of domestic and imported coal in Turkey by machine learning methods
by Mehmet Kayakuş
Abstract: Coal is an energy source with high economic value. Although Turkey has its own coal reserves, it remains inadequate due to the increasing energy demand. Hence, it imports a significant amount of coal from other countries. There are significant differences in the tonnage prices of imported and domestic coal in Turkey. Imported coal is approximately four times more expensive than domestic coal due to the quality. It is important to classify coals as imported and domestic due to their pecuniary value. In this study, considering the calorie, sulphur, volatility and ash values of 1,665 coal samples, coal was classified into two categories as imported and domestic. Support vector machines from machine learning methods, decision trees and Bayes theorem are used for classification processes. As a result of the classification made with decision trees, the accuracy is 99.7%; 99.099% with support vector classification and 96.997% according to Bayes theory. [Received: 25 January 2021; Accepted: 26 July 2021]
Keywords: imported coal; domestic coal; machine learning; classification; Turkey.
Application of neural networks in synthetic log generation
by Pham Son Tung, Nguyen Ninh Giang, Nguyen Dac Nhat, Ta Quoc Dung
Abstract: This paper aimed to study the application of artificial neural network in solving the problem of missing logs, a problem frequently encountered in petroleum industry. Firstly, fully connected neural network (feed-forward neural network) and long-short-term memory network (recurrent neural network) were used to generate synthetic logs in order to determine the most suitable approach to the missing log issue. Secondly, various methods of data pre-processing, such as normalisation, outlier, and principal component analysis, were also analysed so that their effect on the application of neural network in solving incomplete log problem can be evaluated. Finally, the influence of number of stratigraphy layers on the accuracy of using neural networks to solve missing logs problem was equally considered in this research. The results showed that the most accurate way to generate synthetic logs is to use feed-forward neural network for one stratigraphy layer while the data pre-processing method should be normalisation. [Received: August 17, 2020; Accepted: June 21, 2021]
Keywords: synthetic logs; neural networks; data pre-processing.
Impact of temperature increases on the formation of carbon monoxide during lignite storage
by Petr Buryan
Abstract: This article presents our research on the formation of carbon monoxide (CO) through low temperature oxidation of lignite coal during its long-term storage in the coal bunkers of fluidised bed boilers. Our work shows that CO concentration in the vicinity of coal storage facilities poses real danger to the operating staff, especially in cases when the temperature of coal or the facility may suddenly rise. The experiments with lignite samples revealed CO can be released at temperatures higher than ambient (ca 50-180°C) in concentrations of up to 2,500 ppm. The cause is the oxidation of stored coal matter by air. We showed that any step increase in the temperature of the coal always leads to immediate short-term peak increase in CO formation. In all cases, these peak CO concentrations reached levels higher than both the maximum permissible exposure limit and the maximum permissible concentration in the working environment air. [Received: September 27, 2019; Accepted: August 7, 2020]
Keywords: storage; lignite; carbon monoxide; coal bunker.
Petroleum crude slate effect on H-Oil performance
by Dicho Stratiev, Ivelina Shishkova, Ilian Kolev, Dobromir Yordanov, Vesislava Toteva
Abstract: Sixteen petroleum crudes and an imported atmospheric residue originating from Russia, Azerbaijan, Greece, Italy, Kuwait, Iraq, Iran, Saudi Arabia, Tunisia, and the USA have been processed in the LUKOIL Neftohim Burgas (LNB) refinery, and their effect on the ebullated bed vacuum residue H-Oil hydrocracking (EBVRHC) performance has been evaluated. The vacuum residue conversion in the LNB H-Oil EBVRHC varied between 55% and 82% depending on the crude blend processed in the LNB refinery. It has been established that among all vacuum residue SARA fractions during EBVRHC, the resins have the highest conversion, followed by the naphtheno-aromatics while the saturates show the lowest conversion. Depending on the petroleum crude origin the behaviour of the most problematic VR asphaltene fraction has been found to be different suggesting distinct propensity of the asphaltenes from the different petroleum crudes to participate in radical recombination reactions leading to the formation of additional amounts of core-condensed asphaltenes. [Received: July 6, 2020; Accepted: August 19, 2020]
Keywords: petroleum crude; hydrocracking; vacuum residue; conversion; sedimentation; kinetics; saturates; aromatics; resins; asphaltenes.
Study on application timing and solution performance optimisation of composite system after polymer flooding
by Leiting Shi, Shijie Zhu, Xiaoqin Zhang, Yuchi Zhou, Zhongbin Ye
Abstract: The appropriate application timing and application system of compound flooding can maximise the recovery after polymer flooding. Taking a polymer flooding heavy oil reservoir as an example, the application timing and solution performance of the composite system are analysed and studied, respectively. The results show that the application time of composite flooding should be at the end of the effective mobility control time of polymer flooding after the disappearance of polymer action. Increasing RRF can effectively prolong the effective flow control of polymer flooding. Among the solution properties of the composite system, the contribution of solution viscosity is relatively larger, accounting for 54.88%. After considering the effect of the complete polymer flooding control process (polymer flooding + subsequent water flooding = displacement of 0.44 PV), a composite system with a viscous system as the main component (100-200 mPaⷀs) and an appropriate interfacial tension reduction is further developed. [Received: August 7, 2020; Accepted: September 11, 2020]
Keywords: polymer flooding; mobility control; combination flooding; oil displacement effect; application timing.
The spatial distribution of the strike angles derived from EIGEN 6C4 gravity model - a new possibility for oil and gas exploration?
by Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk, Václav Cílek
Abstract: We discovered a correlation between the 'combed' strike angles (one of the gravity functions derived from a gravity field model) and regions with oil, gas, shale gas deposits or ground water, paleolakes or impact craters. The spatial distribution of the combed strike angles may indicate a new cheap and accessible geophysical tool for recognition of some potential oil and gas areas. We work with the global gravity field model EIGEN 6C4 providing a ground resolution of about 10 km and a precision typically 10 mGal. First, we test the well-known oil/gas fields; this attests the success of the proposed methodology. Then, we extrapolate outside the known zones. The new method may be an inexpensive tool for frontier areas in terms of decreasing the risk of deposit exploration. An extensive supplementary material is added. [Received: March 29, 2020; Accepted: September 18, 2020]
Keywords: oil/gas exploration theory; oil/gas exploration methodology; physical geodesy; satellite gravimetry; earth's gravity field models; EIGEN 6C4 gravity field model; geoapplications; gravity aspects; gravity disturbances; Marussi tensor; virtual deformations; combed strike angles; correlation between combed strike angles and oil/gas deposits; impact craters.
An efficient design for a downhole water loop to control water production from oil wells
by Mohammadsajjad Zeynolabedini, Mehdi Assareh
Abstract: This work presents an effective design of downhole water loop (DWL) based on a case study from literature. At the beginning, a comparative study of conventional production and DWL is performed to show the relative importance of DWL based on decrease in watercut and increase in oil production rate. The net present value (NPV) of the DWL technique is 4.52E+07 [$], while the NPV of conventional production is 3.26E+07 [$]. Prior to optimisation, DWL sensitivity to the opening lengths, distance between upper and lower openings in water zone (water drainage-injection distance or D/I spacing) and water drainage rate are analysed. Two different optimisation procedures, sequential and simultaneous, are applied to find an optimised design. The NPVs are improved in this way considerably, from 4.52E+07 [$] to 7.07E+08 [$] in simultaneous mode and 6.99E+08 [$] in sequential mode. Finally, anisotropy effects are analysed for its impact on NPV decreasing. [Received: March 18, 2020; Accepted: September 21, 2020]
Keywords: production operation; downhole water loop; DWL; oil wells; stochastic optimisation; water production control.
Influences of reservoir rock and fluid properties on cyclic steam stimulation efficiency in naturally fractured reservoirs
by L. Saif Elkamel, Behnam Sedaee
Abstract: Steam injection in NFRs provides an extremely challenging problem as well as a potentially efficient EOR method. Coupling of the two distinct and contrasting matrices and fracture systems results in more complications as a result of steep changes in fluid properties due to the thermal effects of steam injection. In this research effort, attempts have been made to simulate the cyclic steam stimulation in NFRs containing heavy-oil and also analyse the influences and contribution of different reservoir parameters on oil recovery (RF), cumulative steam oil ratio (COSR) and cumulative water oil ratio (CWOR). The results obtained show the advantage of a fracture system in conducting heat into the rock matrix, because of the large surface area exposed to heating. The results obtained from the Sobol analysis show that oil viscosity, fracture horizontal permeability, matrix wettability and capillary pressure are the most effective reservoir parameter which affect the performance significantly. [Received: August 4, 2020; Accepted: October 17, 2020]
Keywords: cyclic steam stimulation; CSS; naturally fractured reservoir; NFR; heavy oil; recovery factor; RF; technical sensitivity analysis.
Definition of an oilfield production strategy through integrated simulation of manifolded production system and reservoir
by Igor Ricardo De Souza Victorino, João Carlos Von Hohendorff Filho, Marcelo Souza De Castro, Denis José Schiozer
Abstract: This study presents an integrated simulation of reservoir and manifold-based production system for oil production and the influence of such equipment in oilfield management. The production strategy analysis methodology was evaluated in five sequential separated stages: 1) allocation of all wells (producers and injectors); 2) number of wells (suitable for field production); 3) use of manifolds (number of manifolds, allocation and groups of wells connected to them); 4) sensitivity analysis involving the variation of the entire gathering system diameters; 5) platform allocation. Each stage considered the best result of the previous stage. The results identified the importance of each stage in the production strategy and presented an ideal configuration with adequate financial return to produce this field. Besides that, the analysis identified the most important stages for more complex optimisation with less discontinuities, convergence problems and computational effort. The methodology contributed to an evaluation and improvement in the production strategy. [Received: July 29, 2020; Accepted: October 6, 2020]
Keywords: simulation; integration reservoir and production system; production strategy; manifold.
Investigation on surfactant desorption isotherm to enhance oil spontaneous recovery in a low permeability core
by Ichhuy Ngo, Ronald Nguele, Yuichi Sugai, Kyuro Sasaki
Abstract: Surfactant enhanced oil recovery depends on the interfacial tension (IFT) reduction and wettability alteration in the rock/oil/brine system. An adequate amount of surfactant within the system is vital during the application. The aforementioned problem becomes more sensitive in a low permeability formation when the adsorption is much higher than the desorption. This study, therefore, investigated the surfactant desorption isotherm using sodium dodecylbenzene sulfonate (SDBS) as a surfactant and tight Berea sandstone as adsorbent. The desorption of SDBS was found to follow a Langmuir type isotherm. Owing to the Langmuir characteristics, the desorption increased up to four folds by reducing the salinity of the process water from 3 wt.% to 1 wt.%. The study was extended in a spontaneous imbibition tests for oil recovery. The desorbed SDBS enables an increase in total oil recovery by 2%. The results were subsequent to a more favourable IFT and a mitigation in the narrow-pore blockage. [Received: March 21, 2020; Accepted: October 12, 2020]
Keywords: surfactant adsorption; surfactant desorption; enhanced oil recovery; EOR; spontaneous imbibition; Langmuir isotherm; sodium dodecylbenzene sulfonate; SDBS; low permeability; Berea sandstone; surfactant precipitation; pore blockage.
Mobilisation and stabilisation flow of multiple oil slugs in a capillary model
by Alexandre Gutierry Melo De Oliveira, Liming Dai
Abstract: This research aims to investigate the mobilisation and flow of multi-oil slugs in a capillary model saturated with water, for simulating the motion of oil droplets trapped inside the porous medium of an oil reservoir. The mobilisation and stabilisation points of multi-oil slugs in the model are quantified under various experimental conditions with different numbers of oil slugs. The maximum pressure required to mobilise the oil slugs is identified. For generating a stabilised flow, the oil slugs are all found experiencing consecutively the following pressure and movement change patterns: motionless - slowly increased pressure drop - dramatically increased pressure drop - flow impending - flow stabilised. An analysis comparing the pressure drop and oil slugs travelling displacements for one, two, and three oil slugs are carried out. The research contributes to a better comprehension of the mechanism of mobilisation and the flow of multi-oil slugs subjected to capillary force and externally applied pressure. [Received: July 31, 2020; Accepted: October 26, 2020]
Keywords: oil recovery; porous media; multi-slugs; water flooding; pressure drop.
Optimisation of smart water shock flooding in carbonates: effect of soaking time
by Mahmood Fani, Peyman Pourafshary
Abstract: Smart water shock flooding (SWSF) is proposed as an alternative to the conventional method of employing low salinity water. It is confirmed that the asserted method is financially viable when compared to the conventional method. The effect of soaking time after SWSF was studied in order to mend the enactment of engineered slug shock injection. The depicted scheme provided enough time for the smart water to intensify the interaction at the surface of the formation rock; hence, it causes fluctuation in the wettability condition of the overall process. Contact angle measurements were used, in addition to pH evaluations, to detect an optimum soaking time for the flooding. Experiments showed that soaking the sample in the smart water during core flooding experiments leads to drastically higher incremental recovery, compared to the conventional injection scheme. Hence, the proposed method can inexpensively improve oil recovery by combining the effects of soaking and SWSF. [Received: July 28, 2020; Accepted: October 22, 2020]
Keywords: smart water; enhanced oil recovery; conventional oil reserves; unconventional oil reserves; low salinity water flooding; smart water shock flooding; optimisation; petrochemistry; surface chemistry.
Environmental analysis of Turkish upstream petroleum sector
by Emre Özgür
Abstract: In this manuscript, an environmental analysis of Turkish upstream petroleum sector has been performed from the methane emission point of view. Methane is emitted during the production of crude oil and natural gas. Although methane's lifetime in the atmosphere is much shorter than carbon dioxide, methane is more efficient at trapping radiation than carbon dioxide. The flared gas amount of Turkey resulting from upstream petroleum activities were estimated and compared with the satellite data, which shows consistency. It is observed that the flared gas amount of Turkey based on the upstream petroleum activities is low due to the production level and the characteristics of crude oils. The annual flared volume of associated gas is estimated as 15 million m3 and the vented methane is estimated as 3 million m3. Carbon dioxide emission of the sector were also estimated with some assumptions. [Received: July 28, 2020; Accepted: October 22, 2020]
Keywords: upstream petroleum; flaring; greenhouse gas; emission.
Methanol thiolation: a feasible process solution for H2S recovery in refineries
by Mohammad Reza Shabani, Mohammad Ali Moosavian, Sayed Javid Royaee, Yahya Zamani
Abstract: Hydrogen sulphide and methanol can react with each other in the methanol thiolation reaction to produce methanethiol. In this paper, the methanol thiolation process is investigated to remove H2S in refineries. A feasibility study to replace sulphur recovery units in refineries with a methanol thiolation unit was conducted. The methanol thiolation process is simulated, and concept of process is developed. Also, the main equipment is sized, the capital cost is estimated, the operating cost is calculated, and the financial parameters are evaluated for the methanol thiolation unit. The financial results are compared with a conventional process consisting of amine and sulphur recovery unit (SRU). The result of the economic evaluation of purposed units shows that capital cost reduction of 70%, an operating cost increase of 95%, and an internal rate of 79.7%. The above results showed that the mentioned unit is feasible due to the economical evaluation point of view. [Received: August 3, 2020; Accepted: October 26, 2020]
Keywords: methanol thiolation; sulphur recovery; off-gas; hydrogen sulphide; refinery.
Special Issue on: ICCESEN-2019 Sustainable Research on Geo-Energy and Geo-Environmental Sciences
A new algorithm to improve the energy efficiency of a coal-fired thermal power plant by determining the optimum excavation parameters in an opencast lignite mines
by Ali Can Ozdemir, Ahmet Dag
Abstract: An essential problem in the production of lignite is that the produced lignite fails to meet the working conditions of the coal-fired thermal power plant. This leads to both an increase in the unit energy cost and a decrease in energy efficiency. This study aims to eliminate these problems by determining the optimum excavation parameters, which minimised the standard deviation value of the calorific value. Therefore, a computer software was developed for the lignite mines having low calorific values and working with the bucket wheel excavator. This software was applied to Kışlaköy lignite mine and it was observed that a total of 576 alternatives were evaluated and the optimum excavation alternative was determined. Also, the variance reduction ratio calculated with the input and output variance is 0.14. These results indicated that this software is a solution to problems in the coal-fired thermal power plant and the importance of using it. [Received: September 27, 2019; Accepted: September 9, 2020]
Keywords: thermal power plant; opencast lignite mine; excavation parameter; optimisation; energy efficiency.