International Journal of Oil, Gas and Coal Technology (28 papers in press)
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.
Machine learning and data mining assisted petroleum reservoir engineering: a comprehensive review
by Rupali Purbey, Harshwardhan Parijat, Divya Agarwal, Devarati Mitra, Rakhi Agarwal, Rakesh Kumar Pandey, Anil Kumar Dahiya
Abstract: The oil and gas industry faces several challenges associated with managing massive datasets and extracting relevant information. The machine learning tools have proven to be significantly valuable for analysing complex, heterogeneous data and produce quicker and more reliable outcomes even on large-scales. Machine learning and data mining tools have been applied in several aspects of the upstream oil and gas industry, such as exploration, drilling, reservoir engineering, and production forecasting. This review has been explicitly focused on machine learning and data mining implementations in reservoir engineering, including reservoir characterisation and performance prediction, well test analysis, well logging and formation evaluation, and enhanced oil recovery operations. The commonly used statistical measures for classification and regression models have been discussed as well. The observations from the review have led to suitable suggestions that shall enrich the research in this area. [Received: 29 July 2021; Accepted: 30 October 2021]
Keywords: machine learning; data mining; prediction model; neural network; statistical measure; petroleum; reservoir engineering; performance prediction; well test; enhanced oil recovery.
Optimum directional well path design considering collapse and fracture pressures
by Oveis Farzay, Ali Shakouri, Raoof Gholami, Adel M. Al-Ajmi
Abstract: Well path optimisation is often done based on the wellbore stability where the production related concerns are ignored. In fact, many of the studies carried out in the past have not included hydraulic fractures into their calculations. In fact, an optimum path for wellbore should not only provide the maximum stability during drilling but also offer a relatively low pressure to fracture the formation in the production stage. In this study, attempts are made to provide a methodology to determine an optimum well path for drilling, hydraulic fracturing and production stage using wellbore stability analysis in different stress regimes. An analytical model was proposed and used to determine the collapse pressure and fracture gradient during drilling and hydraulic fracturing at various azimuths and inclinations. The results obtained revealed that the well path does not changes in a normal faulting regime during production. However, the azimuth and inclination of wells may need to be changed in the strike-slip and reverse fault regimes for a better drilling and fracturing. It was also found that deviated wells can be a better option in normal and strike-slip stress regimes, but further studies might be needed to confirm these findings. [Received: March 15, 2021; Accepted: October 10, 2021]
Keywords: Wellbore stability; well path; hydraulic fracturing; stress regime; Mogi-Coulomb.
Experimental study on flow and entrainment characteristics of an ejector in petrochemical flare system
by Jiamin Ma, Jinting Zhang, Jiedong Zhang, Meili Liu, Changyan Kong
Abstract: Flare systems can promote rapid and efficient combustion, using a pre-mixing device with nozzles and mixers, but there is a research gap in exploring gas flow characteristics. This study designs an ejector to improve petrochemical flare system performance, based on analyses of gas flow and entrainment characteristics. A hot wire anemometer is used to measure the gas flow behaviour in the ejector mixer. The results show that an increase of the number of nozzle orifices is conducive to premixing, and the distance between nozzle outlet and mixer inlet has limited influence on entrainment. The frequency spectrum shows the mixer is filled with high oscillatory random turbulence, which causes a high degree of noise. The results improve our understanding of the internal flow characteristics of an ejector which can be used to optimise ejector design and reduce noise. [Received: March 9, 2021; Accepted: October 29, 2021]
Keywords: petrochemical flare system; ejection coefficient; entrainment; ejector; noise; combustion.
Zeta potential measurements for adsorption capacity calculation: case study for a system of natural coal and surfactants
by Roman Maršálek
Abstract: The work deals with the parallel monitoring of adsorption and changes in zeta potential. A sample of natural subbituminous coal was selected as the adsorption material. The changes in the zeta potential values were then used to calculate the amount adsorbed. To calculate the adsorbed amount, we used a modified Langmuir equation, in which we replaced the adsorbed amount with zeta potential values. The results of the adsorbed amount calculated on the basis of the analytical determination of the equilibrium surfactant concentration were compared with the results calculated on the basis of the changes in the zeta potential. The difference between the theoretical and experimental value of the adsorbed amount was about 10% in the case of the highest initial surfactant concentration. The measurement of the zeta potential can be used to assess the quantity of the adsorption process. This approach is possible especially in the case of monolayer coating. [Received: August 28, 2021; Accepted: December 20, 2021]
Keywords: surfactants; adsorption; subbituminous coal; zeta potential.
The application of FMEA to study the critical barriers to deploying carbon capture and storage in a Thai petroleum refinery
by Amornrat Sethi, Parames Chutima
Abstract: Carbon capture and storage (CCS) has not been considered a competitive greenhouse gas mitigation technology in Thailand causing the lack of resources and incentives to promote its development and deployment. In this research, the critical barriers preventing the deployment of CCS technology at the Thai petroleum refinery is identified. The barriers are organised using the technological-organisational-environmental (TOE) framework and the risks associated with them are assessed using failure mode and effect analysis (FMEA). The findings show the lack of capacities in the organisation and the lack of support from the government, more than the technical concerns that are preventing the deployment of the CCS technology at the Thai petroleum refinery. The outcome of this study is a roadmap with short, medium and long-term action plans, and suggestions of strategies and policies to overcome the critical barriers and improve the Thai petroleum refinerys readiness for the deployment of the CCS technology. [Received: 8 March 2021; Accepted: 11 December 2021]
Keywords: carbon capture; carbon storage; petroleum refinery; failure mode and effect analysis; FMEA.
A productivity model for vertical wells with horizontal multi-fractures
by Tianyu Luo, Songxia Liu, Shuai Liu
Abstract: Hydraulic fracturing is an important technique for reservoir stimulation. However, the productivity of vertical wells with horizontal fractures in shallow formations for quick reservoir evaluation have been under-researched. In this study, we approximate the actual flow by four regimes: 1) radial flow in far field; 2) vertical linear flow in near fracture area; 3) radial flow in near fracture area; 4) radial flow inside the fracture. Then we established an analytical productivity model for vertical wells with multiple horizontal fractures in shallow formations. For one fracture, the result deviation of our model is less than 5.3% from the classical method. For four fractures, our result is within 9% of deviation compared with CMG numerical simulation software. This model can be used to optimise parameters of horizontal fractures. [Received: 11 November 2020; Accepted: 2 January 2022]
Keywords: vertical well; horizontal fracture; productivity; analytical model; fracture optimisation.
Isothermal and non-isothermal multiphase flow steady-state simulation of offshore production systems using ALFAsim
by Juan Eliseo Prado Rojas, Franciani Godert, Antonio Marinho Barbosa Neto, Marcus Vinícius Canhoto Alves
Abstract: This paper presents ALFAsim, a new commercial software tool for the simulation of transient and steady-state multiphase flows in tubes and pipelines. The main goal of this work is to show that ALFAsim's one-dimensional multiphase flow simulator models can reproduce accurately an offshore production system with isothermal and non-isothermal study cases in steady state condition considering field data extracted from the literature. The difference when simulating a case when temperature effects are present is investigated and different parameters like hold-up, void fraction and phase velocities are analysed. A discussion about these effects linking them to observations in the open literature. The software is tested with field data from the open literature and the results obtained with ALFAsim are within +-15% deviation range. [Received: July 5, 2021; Accepted: October 9, 2021]
Keywords: multiphase flow; heat transfer; steady state simulation; oil and gas production systems.
Occurrence characteristics and relation to oil and gas distribution of bedding fractures in tight sandstone
by Yande Zhao, Weili Wang, Ruiliang Guo, Jing Zhao, Xiao Hui, Weibin Wang
Abstract: The existence of bedding fractures has a very important influence on the formation and distribution of tight sandstone oil and gas reservoirs. In this paper, the occurrence characteristics of bedding fractures and their influence on oil and gas distribution were preliminarily studied. The results show that bedding fractures are generally developed in high energy hydrodynamic environments such as river channel, sea (lake) bank and beach, in which parallel bedding is the main type. The existence of dark minerals leads to weak laminar adhesion. Beddings weak the bond force of laminae due to the existing of dark minerals. The pore development condition of bedding fractures is better than that of the upper and lower sandstone laminae. Influenced by these, bedding fractures become an important channels for hydrocarbon migration. [Received: 23 April, 2021; Accepted: 2 January, 2022]
Keywords: occurrence characteristics; oil and gas distribution; bedding fractures; tight sandstone oil and gas reservoirs.
Reservoir characteristic and its relationship with estimated ultimate recovery of Jurrasic tight shelly limestone reservoir in the central Sichuan Basin, Southwest China
by Shaoyong Wang, Yuan Wang, Denghua Li
Abstract: A combination of reservoir geological factors and a decline curve approach were applied in a play wide analysis, to reveal the relationship between the reservoir characteristics and estimated ultimate recovery (EUR) of the tight shelly limestone reservoir of Daanzhai Formation. As a result, all the oil bearing matrix pores and fractures in the reservoir correspond to the exponential decline, logarithmic decline and power law exponential decline with diminishing EURs of 86.1 MSTB, 39.3 MSTB and 5.9 MSTB (Mille Standard Tank Barrel) (P50) respectively. The proportions of megapores, macropores, mesopores, micropores, and nanopores in the reservoir were 1.6%, 3.7%, 18.1%, 27.8% 27.8%, and 48.8% respectively, and the corresponding EUR ranges tended to be above 294 MSTB, 110 MSTB to 294 MSTB, 37 MSTB to 110 MSTB, 4 MSTB to 37 MSTB, and below 4 MSTB. Thicknesses of fracture segments and thickness ratios of dissolved cave segments to the reservoir were positively linearly related to the EUR. [Received: April 13, 2021; Accepted: November 26, 2021]
Keywords: reservoir space; EUR; tight shelly limestone; Daanzhai formation; Sichuan Basin.
Systematic investigation of the conversion of asphaltenes during hydrothermal upgrading process of heavy crude oil in the presence of supercritical water
by Djimasbe Richard, Ameen Ahmed Al-Muntaser, Michael Kwofie, Rustam R. Davletshin, Mikhail A. Varfolomeev, Boudkhil Affane, Dmitry Aleksandrovich Feoktistov
Abstract: This study is devoted to investigating the transformation of asphaltenes of heavy oil in the supercritical water (SCW) with (water/oil of 1:2, 1:1 and 2:1) at 400 C. The results indicated that increasing the ratio of water/oil, the amount of maltenes increases from (78.39%-85.27%) to (82%-94.2%) and the asphaltenes decreases from 6.33% to 2.58% and 6.33% to 1.14%, respectively. FTIR spectroscopy and GC/MS shown that the maltenes yields increase because of a mechanism reactions of dealkylation of aromatic structures which took place, resulting an increase of aromaticity asphaltenes and alkyls structure (-CH3 and -CH2-) in maltenes fractions. Therefore, the optimal condition of upgrading are of (water/oil of 2:1), the time between 30-60 min with a significant decrease of asphaltenes. This average size of asphaltenes ranging from 79.48 nm to 72.97 nm can decreases the early deposition velocity on the equipment during the production and transporting process. [Received: 21 July 2021; Accepted 26 August 2021]
Keywords: heavy oil; hydrocarbon; supercritical water; SCW; conversion; upgrading; asphaltenes; cracking; dehydrogenation; GC-chromatography; FTIR spectroscopy.
Analysis of pilot scale packed absorption towers for hydrogen sulphide removal from syngas by model simulations and experimental data
by Ersin Üresin, Mahmut Ateş, Fehmi Akgün
Abstract: A 1 MWth pilot plant was operated for syngas and liquid fuels production from low calorific value (2,000-2,500 kcal/kg) lignites. The coal feedstock utilised had relatively high sulphur content (approx. 2.5 %) that was mainly converted to hydrogen sulphide (H2S) by gasification process. Structured packed absorption columns were designed and utilised with main performance target of H2S outlet concentration (less than 1 ppmv) with minimum caustic utilisation. H2S removal targets were reached as 0.2-0.5 ppmv range at the outlet of the second column. Recent rate-based modelling approach was preferred for columns since it was evaluated as more representative than traditional equilibrium-stage modelling method. Gas phase, liquid phase, overall mass transfer coefficients and enhancement factors were analysed for different pilot plant operation parameters. It was found that simulation results by 'Hanleys model' for mass transfer calculations suited better to our experimental data when other empirical models were considered. [Received: 19 May, 2021; Accepted: 25 December, 2021]
Keywords: absorption column simulation; absorption column validation; gasification; hydrogen sulphide (H2S) absorption; hydrogen sulphide (H2S) removal.
Production and characterisation of biodiesel extracted from Indian bamboos
by Renjith Krishnan, Lalhmingsanga Hauchhum, Rajat Gupta, Gokul Gopan
Abstract: Here, bamboo types found in India such as Dendrocalamus asper, Pseudosasa japonica, Dendrocalamus giganteus, Sinarundinaria falcata, and Bambusa vulgaris are considered for the thermochemical conversion process. Primarily, these bamboos are converted to bio-oil by the pyrolysis process and found that Bambusa vulgaris yields more bio-oil than all other bamboos. Later, the bio-oils generated from bamboos are converted to biodiesels through the transesterification process. The properties such as relative density, acid number, kinematic viscosity, cetane number, flash point, cloud point, pour point, ash content, carbon residues, and higher heating value of all biodiesels are done. It is found that biodiesel generated from Bambusa vulgaris has the property values neared to standard biodiesel, so the properties of different blends of Bambusa vulgaris biodiesel with petro-diesel are also found. Here, the result shows that the blend BV15 is suitable for CI engines as it keeps all the property values of good biodiesel. [Received: 21 November 2021; Accepted: 13 January 2022]
Keywords: bamboo; bio-oil; biodiesel; pyrolysis; transesterification.
Influence of relative permeability, capillary pressure, and well orientation in the geological carbon sequestration in a saline aquifer
by Abhishek Gupta, Akshoy Ranjan Paul
Abstract: In carbon capture and sequestration (CCS), geological sequestration of carbon dioxide (CO2) in deep saline aquifers with porous and permeable rocks is one of the most feasible among various solutions to sequester CO2. Here, the TOUGH2 numerical simulator was validated with the analytical model developed predicting the CO2 behaviour in confined saline aquifers. The sensitivity of the numerical model was examined by changing the model of fluid relative permeability (RP) and capillary pressure (CP) functions. Coreys RP functions and Van Genuchtens CP function is most effective to capture the gas saturation (SG) well. The effect of CO2 injection, well orientation, and its length in a simplified saline aquifer model are also demonstrated. This study reveals that the horizontal well configuration is most acceptable. For the same injection well length (at 100 m), 22% drop in the pressure rise is computed in horizontal well as compared to its vertical counterpart. [Received: October 9, 2021; Accepted: February 7, 2022]
Keywords: carbon capture and sequestration; CCS; CO2 geological sequestration; saline aquifers; relative permeability; capillary pressure; well orientation.
Improvement of roller cone drill bit design by using finite element method and experimental study
by Hassan Mohammadi Majd, Behrooz Hassani
Abstract: An approach for increasing the rate of penetration (ROP) of roller cone bits is presented. The proposed approach is based on 3D finite element method (FEM) simulation as well as field test results that were carried out on the Aghajari formation located in the southwest of Iran. In order to reduce the operation time by improving roller cone bit design, the FEM simulation of the complex nature of the contact between the roller cone bit and the formation was performed and the obtained results were compared with the field test data. Results were employed to improve the geometry of the bit profile. Based on the improved design, a roller cone bit was manufactured and employed in the field experiment to assess the performance and to verify the numerical simulation. The results show a positive effect of the improvements on the ROP which leads to a considerable reduction in drilling costs. [Received: September 15, 2021; Accepted: February 26, 2022]
Keywords: roller cone bit; finite element method; FEM; profile design; Drucker-Prager; rate of penetration; ROP.
Optimisation research on a thin coal seam isolated island coal face mining back channel layout and its support parameters
by Bo Xue, Yong Zhang, Chen Wang, Yong Liu, Yu Fei Tian, Yuyang Wang
Abstract: The large deformation and serious failure of the anchor bolt (cable) of a thin coal seam island coal face retrieval mining roadway is a very difficult technical problem to solve. This article is based on the background of the Jizhong Energy Company Handan Mining Group Guo Erzhuang mine 22204 face mining. Through research, theoretical analysis, numerical simulation and experimental methods that revealed the characteristics of the perimeter rock of the roadway and the destruction mechanism, the composite support scheme of 'anchor + anchor cable + lining' was designed to calculate the reliability of the ultimate bearing capacity of the scheme. The simulation analysis of the design with numerical simulation software was used to verify the rationality of the support scheme. Finally, the composite support was successfully applied in the Guo Erzhuang mine. The onsite monitoring results showed a 64% reduction in the roof subsidence and a 70% reduction in the deformation of two gangway. The support scheme effectively controlled the convergent deformation of the retrieval roadway and achieved good industrial testing expectations. The results of the research could provide a reference for the control technology of a thin coal seam island coal face retrieval roadway under similar geological conditions. [Received: October 30, 2020; Accepted: February 03, 2022]
Keywords: thin coal seam; island coal; surrounding rock control; support optimisation.
Polymeric flocculants: agglomerate investigation of fines and sand particles at multiphase flow
by Noor 'Aliaa Amira M. Fauzi, Tarek Ganat, Khaled Abdalla Elraies, Suzalina Zainal, Najeebullah Lashari, Wasan Saphanuchart, Tushar Sharma
Abstract: For oil engineers, sand production control is one of the most important issues due to the present global oil price situation. Solids are prevented from being transported by capturing fines and sand within the separator. Particle size was determined by evaluating polymers in terms of performance, rheology, and compatibility. In this work, the main objective is to reduce fines and sand transfers that cause significant surface equipment issues. To evaluate the agglomeration effectiveness of two types of sand, sand samples A and B. Adsorption effectiveness determines the newest chemical formulation. Experiments on sand, fluid, polymer, and agglomeration performance (bottle tests and dynamic flow tests). A combo-polymeric system (high aggregation at 1% KCl and 100 mg/L combo-polymer mixture) shows rapid agglomeration. [Received: August 10, 2021; Accepted: February 05, 2022]
Keywords: agglomeration; chemical; hydrocarbon; polymer; sand; viscosity.
Experimental evaluation of imbibition effect in Mahu conglomerate reservoirs
by Jing Zhang, Jianhua Qin, Xibin Fan
Abstract: Since hydraulic fracturing fluid plays a significant role in the soaking process, it is interesting to present a study of the imbibition effect by slickwater, brine and guar gum. In this paper, we conducted an experimental study of the imbibition effect on recovering the tight Mahu field, which are the largest discovered conglomerate reservoirs. The recovery performance by different imbibition fluids was compared. Nuclear magnetic resonance (NMR) technique was used to understand what type of pore scale contributes mostly to the imbibition recovery process. Laboratory results indicated that the lowest interfacial tension in some sense is adverse to spontaneous imbibition. The imbibition rate with the largest interfacial tension is the highest. When the bond number falls in a value where both capillary forces and gravity drainage play a role in the recovering process, the oil recovery factor is significant in this case. The oil recovery factor by slickwater imbibition is 40.76%, which is much higher than brine and guar gum. It is observed that the slickwater displacement still recovered additional oil after the imbibition process. [Received: 17 August, 2021; Accepted: 2 January, 2022]
Keywords: imbibition; conglomerates; bond number; recovery mechanism.
Laboratory measurement of oil viscosity reduction due to CO2 injection at high-pressure, high-temperature conditions
by Yaser Alghawi, Hamid Rahnema, Edgard Parra
Abstract: This work presents the use of rolling-ball viscometer to measure viscosity reduction of two dead oil samples injected with CO2 at a temperature of 168 F and a pressure range of 1,114.7-3,514.7 psi. First, a new digital control unit was designed to replace the analogue unit. Afterwards, viscometer was calibrated with Cannon S-6 and S-60 viscosity standards. Next, validation was conducted by measuring the viscosity of n-decane at a temperature range of 77-266 F and a pressure range of 514.7-2,014.7 psi. Next step was the investigation of CO2 effect in reducing n-decane viscosity at 130-266 F temperature range and 1,014.72,014.7 psi pressure range. Results showed significantly reduced viscosities of the CO2 mixture compared to n-decane viscosities, especially at lower temperatures. Afterwards, viscosity of two distinct crude samples was measured at 168 F and 14.7-3,514.7 psi pressure interval. Next, CO2 was injected to respective oil samples and system viscosity was measured at the same temperature and at pressures between 1,114.7 psi and 3514.7 psi. [Received: 20 September 2021; Accepted: 30 January 2022]
Keywords: : viscosity; viscometer; rolling-ball; carbon dioxide; CO2; crude oil; enhanced oil recovery; EOR.
Study on gas migration law and influencing factors of gas drainage
by Yi Wang, Chenguang Zhao, Bing Wu
Abstract: Gas drainage is the main measure of coal mine gas prevent and control. The analysis of gas drainage influencing factors and the optimal design of drill holes are very important to the drainage effect. In this study, a fluid structure coupling model of coal seam gas based on stress equation and transfusion equation is established. The influencing factors of gas drainage are extraction time, occurrence depth, extraction pressure and dill hole diameter. COMSOL software is used to simulate the influence of different factors on gas drainage effect. And the distribution law of the gas pressure is obtained. Finally, the field monitoring of gas extraction in Yuwu mine was carried out, which comparing with the simulation, the results show that the trend of model simulation data is consistent with that of field data, which prove the accuracy of the model. The model can be used to further study the law of gas migration in the process of drainage. And provides a basis for the optimal design of gas drainage. [Received: August 25, 2021; Accepted: March 14, 2022]
Keywords: gas extraction; gas migration law; numerical simulation; fluid structure coupling model; porosity; permeability; drilling optimisation design.
Laboratory simulation of influence of chromatographic effect and microbial oxidation on hydrocarbon microseepage
by Guo-Jian Wang, Yu Zou, Ronald W. Klusman, Jun-Hong Tang, Li Lu
Abstract: An experimental apparatus has been constructed with various experimental conditions to simulate the influence factors of the hydrocarbon gases microseeping from the deep reservoir to the surface. Both the chromatographic effect and the microbial oxidation effect are considered in the experiment. The results show that the vertical hydrocarbon microseepage has the characteristics of a 'jump-over migration effect'; the coupling of a chromatographic process and microbial oxidation has less effect on the composition ratios of microseepage hydrocarbons, whereas the microbial oxidation has a large effect on the isotope values of methane; and the normal alkane and iso-alkane content of vertical microseepage show obvious differences due to the influence of chromatographic process and microbial oxidation. These experimental results may help to identify the genetic origins of the vertically migrating hydrocarbons, and thus promote the successful application of the surface hydrocarbon geochemical exploration technology.[Received: July 1, 2021; Accepted: February 23, 2022]
Keywords: microseepage hydrocarbon; chromatographic effect; microbial oxidation; simulation experiment; geochemical anomaly identification.
Revelation of depositional features in the Paleocene and Eocene in the Mannar basin using amplitude analysis of a 3D dataset
by Asaithamby Dushyendra, Upul Premarathne, Dhamsith Asiri Weerasinghe
Abstract: The Mannar Basin is located between the western coasts of Sri Lanka and the southern coast of India. The Sri Lankan portion of the basin extends over 45,000 km2. It is a deep-water frontier with only two natural gas discoveries. Studies show that the Paleogene and the Late Cretaceous sections have potential hydrocarbon reservoirs. However, their depositional features are little known. The objective of this study was to understand the depositional features in the Paleocene and Eocene sediments in the M2 exploration block in the Mannar basin using a three-dimensional seismic volume. IHS Kingdom software was used for seismic data interpretation. The root mean square amplitude was used to characterise sediment facies in seven time windows having 50-millisecond intervals. The results show the occurrence of an interpreted turbidite fan system in the Paleocene and Eocene sections. A NE-SW trending deep-water canyon channel system occurs in the early Eocene section. [Received: September 11, 2020; Accepted: September 24, 2021]
Keywords: Mannar Basin; Sri Lanka; Seismic data; hydrocarbon; Paleocene; Eocene.
Convective heat transfer in centrifugal pumps lifted wells: the case of South-Eastern Europe waxy wells
by Bojan Martinovic, Marija Zivkovic, Branko Grubac
Abstract: Electric submersible pumps (ESP) are applied in wells where additional energy is needed to ensure discharge of the fluid to the surface through the tubing. At the discharge side of the pump the fluid has bigger velocity, thus the pump induces a forced convection between the fluid and the tubing inner surface. Understanding of convective heat transfer in wellbores and analyses of influential parameters provides a possibility to optimise value of convective heat transfer coefficient in order to avoid well operation problems. As the total fluid is speeded up in the pump, values of Reynolds number decrease after the ESP due to effect of temperature on physical properties of fluids, so flow of the fluids after the pump is determined as laminar. The highest values of convective heat transfer coefficient are expected in zones where wax deposition may occur. [Received: August 25, 2021; Accepted: October 1, 2021]
Keywords: convective heat transfer; ESP pump; fluid properties; well operation issue.
A new approach to maximising drill bit hydraulic horsepower
by Reza Masoomi, Farshid Torabi
Abstract: Bit hydraulic horsepower, impact force, and nozzle velocity are the main characteristics and criteria that are used to optimise drilling hydraulics. An optimised drilling hydraulics program can lead to an efficient bottom hole cleaning and improves the penetration rate. In this paper, a new mathematical model is proposed to maximise the bit hydraulic horsepower at different drilling depths. In this model, the mud circulation rate and pump operating pressure are optimised using numerical optimisation technique of constrained nonlinear multivariable function after a proper objective function is defined and the appropriate linear and nonlinear constraints are applied. The proposed model predicts the optimum value of drilling mud circulation rate with less required data and runtime than commercial hydraulic simulators. The results indicated that the predicted optimal mud circulating values are in agreement with the actual field drilling data with the coefficient of determination (R2) of 0.85 for 17 1/2" hole section. Finally, the relative error of 1.1 % is estimated by comparing the proposed model and drilling office simulator. [Received: November 15, 2020; Accepted: August 20, 2021]
Keywords: bit hydraulic horsepower; BHHP; jet impact force; JIF; constrained nonlinear multivariable function; circulation rate; pump pressure.
Oil withdrawal technological advancement for multilayer field
by Aigul Gusmanova, Raushan Bekbayeva, Aigerim Koyshieva, Abylai Koyshiev
Abstract: The authors discuss the technology for dual pumping technology of oil-producing wells and show its advantages and shortages. It is concluded that the simultaneous-separate oil production project proposed is economically attractive due to increment in oil production, high income terms and short pay-off period even in small and depleted reservoirs. Furthermore, the potential of the proposed project is evaluated in terms of the required facilities and incremental oil production. Dual pumping technology becomes of ever-more use today, since unified well-spacing pattern envisioned for multilayer fields development and operation ensures feasibility of multiple-zone production, and, as a consequence, ramp-up of reserves recovery and oil drainage amount as well. At the same time, practicability of multiple-zone production depends on a number of fraught factors and requires thereof appropriate inventory and current status analyses to be fulfilled with regard to reserves recovery operations. As influx performance study and fluid-bearing characteristic of reservoirs are often incomplete due to field situation, the authors, therefore, follows the task to carry out an efficiency analysis of multi-zone productions based on dual completion technologies. [Received: August 4, 2020; Accepted: August 21, 2021]
Keywords: dual completion wells; geologic characteristics; multilayer fields; reservoir performance.
A numerical method for potential implementation of underbalanced drilling in high pore pressure reservoirs
by Oveis Farzay, Seyedalireza Khatibi, Azadeh Aghajanpour, Ali Shakhouri, Adel M. Al-Ajmi
Abstract: Rising demand to increase productivity as well as reducing drilling damages has encouraged companies to use underbalanced drilling (UBD) technology. In this study, a numerical simulation is applied to evaluate the feasibility of UBD in high pore pressure reservoirs. To achieve this objective, the minimum possible mud weight that ensures wellbore stability is estimated by considering an elastoplastic model. Furthermore, the growth of the plastic area around the wellbore is studied and utilised as an indicator of wellbore instability. When the growing plastic volume around the wellbore equals the drilled wellbore's volume, the finite-difference model results in the optimum mad weight for the formation. Moreover, a detailed study is conducted in the zones with no safe mud windows to determine the optimum applications. The work of the paper is applied to real field data for justification, where the feasibility of UBD implementation in high pore pressure reservoirs is acknowledged. [Received: March 12, 2021; Accepted: September 27, 2021]
Keywords: underbalanced drilling; UBD; numerical simulation; high pore pressure reservoir; elastoplastic model; plastic zone.
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: January 25, 2021; Accepted: July 26, 2021]
Keywords: imported coal; domestic coal; machine learning; classification; Turkey.
Variation in organic crystallite unit for different rank Indian coals by X-ray diffraction
by Yash Jaiswal, Sunder Lal Pal, Lav Kush, Harsh Jaiswal
Abstract: To improve the utilisation of Indian coals more efficiently, chemical and physical reactions between the coal and different reactants need to be established during its use. In view of this, assessment of different structural features of low-high rank Indian coals was performed. The detailed investigation and structural difference between four different rank Indian coals were obtained using XRD. Important structural parameters of heterogeneous coal sample like aromaticity, degree of disorder index, amorphous carbon fraction moreover size of crystallite with their distribution parameters like interplanner lamellar distance, crystallite height and diameter, lamellar counts were determined. The results show that coal rank, carbon content and vitrinite mean reflectance are the main parameters which controls the structure of the organic crystallite unit in coal. The variation of structural parameters with all three controlled variables is presented in this paper. This knowledge is helpful in improvising methods for the use of coal. [Received: March 27, 2021; Accepted: September 24, 2021]
Keywords: Indian coals; organic crystalline unit; aromaticity; X-ray diffraction; XRD; vitrinite reflectance.