bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Alteration-Mineralization in Skarn Deposit System based on Time-Domain Induced Polarization Method Approach in Kasihan Area, Pacitan, East Java
Authors: Seizarsyah Taufik , Setiahadiwibowo Ajimas Pascaning , Maskuri Firdaus , Sutarto Sutarto 
Published: June 2022

This research was conducted in Kasihan, Pacitan, East Java with the aim of knowing the alteration zone and ore mineralization from mineral sediment systems based on the conductivity and resistivity of subsurface rocks in the study area. A geophysical method is needed to map area area area of the prospect of mineral deposits as well as mathematical models in the area research. One of the geophysical methods used in studies of mineral sediment cases is Time Domain Induced Polarization (TDIP). Measurement of Time Domain Induced Polarization method done with configuration dipole-dipole which is arranged relatively straight northeast-southwest as much 2 tracks, with each track having the length of 260 m with an initial space of 20 m electrodes. Targets of the TDIP Method can describe subsurface conditions as far as 48 m. The position of mineralization in skarn deposits in the Time Domain Induced Polarization method at a depth of 25 m below the surface topography shown by high resistivity values >2000 Ωm and >500 msec chargeability in dacite and limestone
Combined Effect of Contact Area, Aperture Variation, and Fracture Connectivity on Fluid Flow through Three-Dimensional Rock Fracture Networks
Authors: Huang Na , Zhang Yubao , Yin Qian , Jiang Yujing , Liu Richeng 
Published: June 2022

Abstract
In order to investigate the combined effect of contact area, aperture variation, and fracture connectivity on the fluid flow through a fractured medium, a series of flow simulations were implemented on two types of three-dimensional discrete fracture network (3D DFN) models constituting fractures having spatially variable apertures and parallel plates, respectively. The flow tortuosity within the 3D DFN models was examined by changing the density, aperture distribution, and closure of fractures. The results show that compared with the 3D DFN models constituting parallel plates, the model with variable apertures provides more pronounced 3D preferential flow pathways. At the individual fracture scale, the preferential flow pathways mostly converge within the void spaces of large aperture, and at the network scale, they are located in the most transmissive fractures within the connected networks. The permeability of 3D DFNs depends not only on the contact area and aperture variation within individual fractures but also on the fracture connectivity and the contact at fracture intersections within the fracture network. Increasing the fracture connectivity tends to enhance the permeability, while increasing the contact at fracture intersections would significantly reduce the permeability. A correlation between the equivalent permeability of 3D DFNs constituting fractures with spatially variable apertures and parallel plates is proposed incorporating the effect of network-scale topology. A tortuosity factor for 3D DFNs is defined based on the proposed model, and it can account for two competing effects when the model is upscaled from individual fracture to fracture network: the permeability reduction induced by contact obstacles at fracture intersections and permeability enhancement induced by increasing the fracture connectivity.
Thermodynamic Model Evaluations for Hydrogen Pipeline Transportation
Authors: Cely Alexandra , Hammer Morten , Andersen Hilde , Yang Tao , Nekså Petter , Wilhelmsen Øivind 
Published: June 2022

Abstract
Equations of state and transport property models for hydrogen and hydrogen mixed with natural gas components relevant for pipeline transport have been evaluated by comparing to experimental data and reference equations of state. The evaluated properties are density, speed of sound, Joule-Thompson coefficient, the isobaric and isochoric heat capacity, viscosity, and thermal conductivity. A temperature span of −10 to 50 °C and a pressure span of 1-300 bara has been set as the target range for pipeline transport. Viscosity and thermal conductivity models have been evaluated for binaries where experimental data are available. The goal of this work was to determine if models already available in commercial simulators can predict fluid properties accurate enough for engineering purposes.
The classical cubic equations of state of Soave-Redich-Kwong (SRK) and Peng-Robinson (PR) with van der Waals mixing rules have been tested with parameters extracted from the common commercial simulations tools Hysys, Unisim, PVTsim Nova and Multifash. In general, the different parameter sets give similar performance. One exception is the H2-CH4 binary, where both Unisim and Multifash use a non-optimal kij interaction parameter. Neither the SRK, nor PR can describe the Joule-Thompson coefficient of hydrogen, and the error lies in the range 50%-100%. The Joule-Thompson coefficient is however small, and the effect of this misprediction on pipeline simulations might not be significant.
For viscosity and thermal conductivity predictions, the SuperTRAPP model in REFPROP 10 as well as simpler viscosity models LGE, LBC and a corresponding-state-principle model of PVTsim Nova have been evaluated. The SuperTRAPP model in REFPROP 10 was found to predict viscosity and thermal conductivity within a reasonable accuracy for pure hydrogen. The simpler viscosity models LGE and LBC overestimate the viscosity of hydrogen by 65% to 90% in the transport domain of interest. For the hydrogen binary systems studied, the SuperTRAPP model for the thermal conductivity and viscosity had errors around 20% at high pressures. Comparing corresponding-state-principle viscosity models with the SuperTRAPP model gave relative deviations in the range 3.9% to 13%. The SRK equation of state is found to perform better than the PR equation of state, with a relative density error below 1% for hydrogen rich systems.
A TIBCO Spotfire® visualization dashboard has been developed for easy access to the evaluation results of the large amount of data and thermodynamic models. A steady-state thermohydraulic analysis for Europipe (Norway to Europe) has been performed to evaluate the effect that using different equations of state and viscosity models have on the thermohydraulic estimations. After a review of the thermodynamic model's performance, clear guidance on model selection for hydrogen transportation is provided.
Stimulation of Conventional Geothermal Wells with Propped Fractures
Authors: Shaoul Josef R. , Park Jason , de Pater C. J. 
Published: June 2022

Abstract
Conventional hydrothermal ("low enthalpy") geothermal reservoirs are already being developed in the Netherlands as a source of heat for greenhouses, district heating. Many of these wells are left with a positive skin after being drilled, and could therefore benefit from stimulation. In order to evaluate the potential benefit of propped fracture stimulation for this type of reservoir, a history match of a real geothermal injection and production doublet was made using an industry standard 3D reservoir simulation model. This model was then used to perform production and injection forecasts for different completion scenarios, including propped fracturing.
All available data (logs, PLT, welltests) was used in creating and history matching the reservoir simulation model. The model was history matched to the individual welltests for both the production and injection well and to a 3 year data set of production and injection data. In order to match the long-term pressure trend, an increase in the size of the thermal fracture in the injection well was needed. The history matching results were compared to the predicted increase in the size of the thermal fracture using a new 3D FEM fracture model. The same model parameters were also used to design propped hydraulic fracturing treatments. The propped fractures were also placed in the reservoir simulation model for both the production and injection wells, to predict the performance of the wells with fracture stimulation.
Although the actual wells used in this study had negative skins to begin with (after drilling), many wells drilled in the same reservoir (Rotliegend in the Netherlands) have positive skins to begin with. Our simulations showed significant improvement in well injectivity and productivity using propped fractures, compared to a well with a typical initial skin of +2 seen in new open-hole wells in this reservoir. Injection pressure was also reduced significantly, to below the regulatory limits on "safe" injection. The new 3D FEM model showed that injection well thermal fracture propagation was strongly affected by small differences in the Young's modulus between the higher and lower porosity layers in the reservoir.
This paper shows, based on actual well data from a real geothermal doublet, the expected benefit from hydraulic fracture stimulation is significant, especially when the wells have a positive skin after drilling. The effect of small differences in rock stiffness on thermal fracture propagation in a geothermal injection well is also a new and surprising result.
Physics-Based Data-Driven Interwell Simulator for Waterflooding Optimization Considering Nonlinear Constraints
Authors: Li Ying , Nguyen Quang , Onur Mustafa 
Published: June 2022

Abstract
When nonlinear constraints such as field liquid and water production rate are imposed onto the problem and need to be honored, optimizing well controls such as producing bottom-hole pressures (BHPs) and injection rates becomes more challenging. Hence, the main objective of this paper is to present an efficient production optimization tool to handle nonlinear state constraints for well-control waterflooding optimization problems. The proposed efficient optimization tool uses our newly improved physics-based data-driven interwell waterflooding simulator (referred to as INSIM-BHP) that handles both rate and pressure controls. Our previous waterflooding optimization applications used an old version of INSIM which only considered the linear constraints and did not incorporate the correct well indices for computing BHPs in the case of well BHP control optimization. In this study, we use our newly developed interwell waterflooding simulator that removes the mentioned restrictions in well-control optimization to maximize the net-present-value (NPV) with nonlinear state constraints. We use a recently developed line-search sequential quadratic programming (LS-SQP) algorithm coupled with stochastic simplex approximate gradients (StoSAG). We tested our proposed methodology on a three-dimensional (3D) channelized reservoir with multi-segmented wells and compared it with a commercial simulator. Results show that our methodology provides optimal well controls that satisfy the specified nonlinear state constraints successfully. In addition, the optimal well controls and NPV obtained from our INSIM-based optimization method compare well with the corresponding results from a high-fidelity commercial reservoir simulator but in a far less computational time. The novelty of our work is its presentation of an improved physics-reduced data-driven proxy simulator (INSIM-BHP) to replace the high-fidelity simulators to simulate the oil saturation and pressures to perform computationally efficient well-control waterflooding optimization under nonlinear constraints.
A Deep-Learning-Based Approach for Production Forecast and Reservoir Evaluation for Shale Gas Wells with Complex Fracture Networks
Authors: Dong Peng , Liao Xinwei 
Published: June 2022

Abstract
This paper proposes a data-driven proxy model to effectively forecast the production of horizontal wells with complex fracture networks in shales. With the multilayer gated recurrent unit (GRU) cell, the proxy model is coupled with newly developed deep learning methods include attention mechanism (Att-GRU), skip connection, and cross-validation to deal with time series analysis (TSA) issue of multivariate operating and physical parameters. In the formulation, the input variables include time, variable bottom hole pressure (BHP), horizontal well length, fracture number, fracture half-length, and fracture conductivity and the output variable refers to the production corresponding to the forecast time. The sample data generated by the boundary element method (BEM) is used in the proxy model learning process. The shuffled cross-validation method is utilized to improve the model accuracy and generalization capability. Results depict that the Att-GRU can accurately forecast the production for shale gas wells with complex fracture networks at a given time and variable BHP while maintaining a high calculation efficiency. The operating and physical parameters analysis indicates that the Att-GRU has learned the underlying physical features of complex fracture networks and variable BHP. Case study from Marcellus shale shows that the proposed Att-GRU is robust in both production forecast and reservoir evaluation, and it is a potential proxy model for transient analysis.
IAST Modelling of Competitive Adsorption, Diffusion and Thermodynamics for CO2-ECBM Process
Authors: Asif Mohammad , Wang Lei , Hazlett Randy , Serikov Galymzhan 
Published: June 2022

Abstract

Objective/Scope
The CO2 emission is one of the main causes for the global warming and it may be controlled by sequestrating CO2 into the geological formation. The coalbed formation provides a dual advantage for CO2 sequestration as CO2 may be stored in coal forever with enhancing the coalbed methane recovery. Thus, the cost of CO2 sequestration may be offset completely or partially. The main objective of the paper was to comprehend the CO2-ECBM displacement using the three concepts viz. competitive adsorption, diffusion, and thermodynamic modelling of coal

Methods, procedure, and process
In this paper, the pure gas isotherm on coal for CH4, and CO2 was evaluated using manometric method. The binary gas isotherm or competitive adsorption was studied using IAST modelling. MATLAB code was developed for the solution of IAST model and Newton Raphson approach was followed. The IAST modelling was done by taking 50%/%50 mole fraction of CH4/CO2. By analyzing the binary gas isotherm, the optimum injection pressure was evaluated. On the same injection pressure, co adsorption isotherm was drawn at different mole fraction of CO2 in gas phase. Separation factor was calculated by taking ratio of CO2 and CH4 in the gas and adsorbed phase respectively. Furthermore, adsorption data was used for discussing the sorption kinetics in coal and diffusion coefficient was evaluated. Furthermore, the thermodynamic parameters were also calculated and integrated with above noted parameters for the methane displacement in CO2-ECBM process.

Results, observations, and calculations
The CO2-ECBM displacement is very much dependent on the competitive adsorption and diffusion process in coal. The surface potential and Henry constant are important parameters for defining the CO2-ECBM displacement. The coadsorption isotherm was drawn at the optimum injection pressure and it shows that methane displacement would be the optimum by taking 11 %/89% mole fraction of CO2 and CH4 for two temperatures i.e., 288 K, 308 K. It is identified through diffusion regime that diffusion coefficient for the binary gas isotherm is the average of the diffusion coefficients of pure CO2 and CH4.

Novel/Additive information
This is the first kind of study which provides the completely integrated approach for describing the methane displacement in CO2-ECBM process. This novel study promotes our understanding of the complex mechanisms of CO2-ECBM displacement process.
Miscibility Study of Flue Gases for a Coupled CCS-EOR Project
Authors: Gonzalez-Perez Alfonso , Barrado Manuel , Pardo Rosario Rodriguez , Ruiz Jesus Montes 
Published: June 2022

Abstract
Miscible hydrocarbon (HC) rich gas injection is a common EOR technique included in the development plan of many Abu Dhabi oil fields. This technology, that provides a very high oil recovery, requires the supply of a gas that is very valuable for other uses or its commercialization. Utilization and storage of flue gases rich in CO2 and N2 can play a key role in lowering the overall reservoir emissions by coupling carbon capture and storage (CCS) with EOR techniques. Thus, the substitution of hydrocarbon gas by these gases is of great environmental and industrial interest. Nevertheless, the change of the injection gas is not straightforward and requires a previous study to ensure the gas miscibility.
The aim of this piece of research is to estimate the minimum miscibility pressure (MMP) of the studied gas, in order to clarify if miscibility conditions are achieved at reservoir pressure. Thus, a comprehensive study was performed applying three different approaches to predict/estimate the MMP:
Empirical correlations from the literature based on experimental results. Experimental measurements with Slim Tube tests. Computer modeling based on equations of state for phase-behavior calculations.
Miscibility of CO2 and N2 was successfully investigated through the three approaches. In the case of CO2, miscibility at reservoir pressure was totally ensured at 120°C since MMP was estimated to be the bubble pressure of the studied oil, more than 100 bar below reservoir pressure. Otherwise, the conclusion of the nitrogen miscibility studies is that N2 gas flooding is not a feasible EOR technique since MMP is far above reservoir pressure. Before completely discarding the use of nitrogen, miscibility of mixtures of HC rich gas and N2 was first studied by PVT simulations. Thermodynamic modelling was compared against experimental Slim Tube tests evaluating HC+N2 mixtures. Laboratory work led to conclude that mixtures with 42% of N2 could be injected at miscible conditions and revealed that simulations overestimate the minimum miscibility pressure of the studied gas mixtures. Finally, miscibility of CO2 and N2 mixtures with typical compositions of flue gases from post-combustion processes were studied using the thermodynamic model retuned with previous experimental measurements.
This work presents a thorough study of minimum miscibility pressure of CO2 and N2 in oil from Abu Dhabi, which is the first step of any EOR project coupled with CCS. The developed methodology covered the three different approaches and the results provide a broad comparison amongst correlated, measured and simulated MMP.
A Practical Approach to Maximise UGS Storage Efficiency in Order to Secure Energy Supply
Authors: Li Limin , Yu Huijuan , Kshirsagar Atul , Samy Ayman , Mao Chuanqin , Qu Lin , Kuswiranto Agung , Gui Feng , Cook Dave 
Published: June 2022

Abstract
The Underground Gas Storage (UGS) working gas capacity is one of the important design parameters for a UGS project. The objective of this paper is to demonstrate a case study from Sichuan area, China, where a fractured carbonate gas reservoir was used for UGS and show the key factors that should be considered to optimize UGS working gas capacity and help to secure energy supply during peak season.
The dynamic simulation model was history matched on both depletion and storage. This model was coupled with 4D Geomechanics effects. It was then employed to capture the key parameters that will affect the working gas capacity. Based on the 4D Geomechanical integrity and facility assessment results, the forecast model was created using the subsurface and surface facility constraints. The study workflow included setting up the forecast model, uncertainty analysis and sensitivity analysis to capture the key driving parameters for the working gas volume. This study also included sensitivities of emergency gas supply during peak winter season.
This study showed that the main factors that determine the UGS working gas capacity are the initial gas in place, tubing head pressure (THP) during withdrawal phase, bottom hole pressure (BHP) during injection phase, well pattern and well count. It was observed that each injection/production cycle is affected by the previous cycles. The simulation showed that the incremental working gas volume represented as a trend can be better fitted by a power function with both THP and BHP. It also demonstrated that lowering the THP limitation is more effective than increasing the BHP limitation. However, this may require surface facility upgrading. The optimum operating condition was identified by considering all engineering and geomechanical constrains such as erosion, wellbore integrity and cap rock integrity. This is used to guide the UGS daily operations with optimum production/injection rate of each well in a safe manner. The study recommended to implement a stepwise strategy to reach the working gas capacity.
This paper presents a novel practical workflow and methodology to implement increased UGS reservoir working capacity. It also provides a practical way to forecast the operational pressure range and quickly predict the deliverability of emergency gas supply under various market demands.
A Universal Method for Predicting the Relative Permeability Data of Low Salinity Injection
Authors: Aljaberi Abdulla , Aghabozorgi Shokoufeh , Sohrabi Mehran 
Published: June 2022

Abstract
Low salinity waterflood (LSWF) injection is an enhanced oil recovery (EOR) method proven effective through extensive experimental studies. Correct implementation of this method in reservoir-scale simulations requires reliable estimation of changes in relative permeability data associated with LSWF. For this purpose, a few models have been suggested based on geochemical interactions, such as the cation exchange capacity of clay, which are case dependent and cannot be applied to all systems.
This study presents a novel semi-empirical model based on incremental oil recovery measured during low salinity injection. Therefore, it can be applied to all rock types, fluid systems, and wettability conditions regardless of the active mechanism. Some mechanisms proposed in the literature relate the additional oil recovery during low salinity injection to measurable parameters such as micro-dispersion. As a result, the kr curves can be constructed using this new methodology by measuring the micro-dispersion.
This method has been validated against five sets of secondary and tertiary coreflood experiments published in the literature. First, the high salinity kr data is obtained by history matching using the CMOST module of CMG software. Then the proposed method and the measured value of additional oil recovery were used to estimate the kr data of low salinity injection. The results showed that the suggested method could predict the oil recovery and pressure drop in secondary and tertiary modes. The high-salinity relative permeability was shifted towards a more water-wet condition in tertiary mode. The kr curve of secondary LSWF showed a significant shift towards a more water-wet condition than tertiary mode, implying lower residual oil saturation. Since the additional oil recovery versus micro-dispersion curve was reported for this rock sample, one can simply predict the kr values of LSWF for other values of micro-dispersion.
Due to the ongoing debate regarding the dominant mechanism during LSWF, there is no universal model for estimating the relative permeability of LSWF in all systems. The model presented in this paper provides a powerful tool for engineers to simulate the LSWF kr data in both tertiary and secondary flooding regardless of the active mechanism.