bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Miscibility on Gas-Oil Gravity Drainage in Fractured Reservoirs
Authors: Suicmez V. Sander , Karpan Volodymyr , Dindoruk Birol 
Published: October 2011

Abstract
A significant proportion of the world remaining oil reserves is residing in fractured reservoirs. Conventional recovery mechanisms may result in low oil recovery efficiencies in such reservoirs. Gas injection may be one of the few techniques, which can boost production from these resources. However, higher capillary pressures associated with the matrix blocks coupled with the extreme hydraulic contrast between the matrix and the fractures may result in ultimate recovery factors significantly lower than the equivalent non-fractured systems. Miscible or near-miscible gas injection may substantially boost the ultimate oil recovery as the interfacial tension and hence the capillary pressure vanishes or diminishes. Furthermore, the viscosity of the oil can be significantly reduced by mixing and interacting with the injectant, leading to further increase in oil drainage rate.
Due to the nature of the problem that originates from the extreme contrast between matrix and fracture, numerically it is considered to be a difficult problem. Therefore, it is important to design an appropriate grid system for this class of reservoir systems. We first validate our model by conducting black oil simulations to match the previously performed gas-oil gravity drainage (GOGD) experiments. We then generate a three-component synthetic oil to perform compositional simulations of gas injection at different enrichment conditions; immiscible, near-miscible and first-contact miscible. We show that ultimate recovery and oil drainage rate significantly increase once the miscibility is developed. In addition, we study the effect of various block boundary conditions that are aligned with various geological artifacts, like horizontally-oriented impermeable shale layers on recovery efficiency. We show that impermeable layers significantly reduce the performance of the gas-oil gravity drainage process for immiscible gas injection, while increasing the recoveries substantially for multiple- and first-contact miscible gas injection cases.
Three-Phase Pore-Network Modelling for Mixed-Wet Carbonate Reservoirs
Authors: Al-Dhahli Adnan R. , Geiger Sebastian , van Dijke Marinus I. 
Published: October 2011

Abstract
Carbonate reservoirs have structural heterogeneities (triple porosity: pore-vug-fracture) and are mixed-to oil-wet. The interplay of structural and wettability heterogeneities impacts the sweep efficiency and oil recovery. The choice of an IOR or EOR process and the prediction of oil recovery requires a sound understanding of the fundamental controls on fluid flow in mixed-to oil-wet carbonate rocks and physically robust flow functions, i.e. relative permeability and capillary pressure functions. Obtaining these flow functions is a challenging task, especially when three fluid phases coexist. In this work we use pore-network modelling, a reliable and physically-based simulation tool, to predict three-phase flow functions. We have developed a new pore-scale network model for rocks with variable wettability. Unlike other models, this model comprises a novel thermodynamic criterion for formation and collapse of oil layers. The new model hence captures film/layer flow of oil adequately which impacts the oil relative permeability at low oil saturation and hence the accurate prediction of residual oil. Pore-networks extracted from pore-space reconstruction methods and CT images have been used as input for our simulations and the model comprises a constrained set of parameters that can be tuned to mimic the wetting state of a given reservoir. We have validated our model with available experimental data for a range of wettabilities. A sensitivity analysis has been carried out to investigate the dependency of relative permeabilities on layer collapse and film/layer flow under various wetting conditions. Additionally, WAG injection has been simulated with different lengths of so-called multi-displacement chains and different flood end-points. The flow functions generated by our model can be passed to the next scales (upscaling) to predict the oil recovery at the reservoir scale and we demonstrate this using a proof-of-concept study.
Optimizing Development Well Placements Within Geological Uncertainty Utilizing Sector Models
Authors: Yuen Bevan , Rashid Omar , Al-Shammari Methgal , Al-Ajmi Fahad , Pham Tony , Rabah Mesdour , Moreno Juan Carlos 
Published: October 2011

Abstract
Uncertainties, particularly in geological parameters are always present and are significant in field and reservoir development. These uncertainties could be those perceived by geologists and engineers or exist in the available data. Industry has been using uncertainty analysis to identify, address and mitigate risk. Field development strategies and well placement depend significantly on reservoir geological characterization, maturity of the depletion stage, technological factors, drive mechanism and other parameters. Well placement optimization is normally performed using a deterministic (most likely) model. The optimum placement of wells within geologic uncertainty is the issue addressed in this paper.
This paper discusses an application of the workflow performing uncertainty analysis on a sector model of a conceptual reservoir and its optimization technique of development wells under geological uncertainty. Tornado plots are used to identify the highest critical parameters among the list of uncertainties of the reservoir. Experimental Design, Proxy Model, and Monte Carlo simulation are then used to generate a density probabilistic distribution of cumulative production to identify the 10%, 50% and 90% probability (P10, P50 and P90) cases. The best field operation strategy is identified by the lowest risk (highest probability) among strategies considered. Optimum injector-producer spacing, producer-producer spacing, horizontal completion, well length and orientation are obtained at pre-defined risk level under geologic uncertainties. Results show that the optimized development plan has reduced the associated risk substantially compared to the pre-optimized case with this process.
Fracture Modeling in a Weakly Fractured Carbonate Reservoir, Offshore UAE
Authors: Williams M. P. , Nivarthi S. S. , Al-Shehhi B. H. , Edwards E. 
Published: October 2011

Abstract
This paper describes the workflow used to assess modeling the impact of fractures (and faults) on the dynamic performance of a Lower Cretaceous reservoir located offshore Abu Dhabi. The reservoir is not highly fractured and the modeling challenge is to identify a practical method to incorporate their impact in a geologic and simulation model. The work plans developed to address these issues consist of four elements of a conceptual fault and fracture model - these are: two groups of diffuse fractures in specified layers; seismic scale faults; and fracture corridors. This paper focuses on learnings from the study of the first two elements of the developed work plans - i.e., modeling the impact of diffuse fractures on water movement.
The workflow began by modelling diffuse fractures at mini-sector scale (single geo-model grid-cell with layers and properties). Fracture parameters have been defined for low-side, most likely and high-side cases based on core data from 80 wells. By preparation of discrete fracture network (DFN) models for these cases and calibration to well test permeability, we are able to define a permissible range of fracture parameter values; and also to define the sensitivity of each fracture parameter. Dual media mini-sector simulation models are then used to compare water breakthrough time and evolution for different DFN models. The mini-sector models are also used to estimate the range of possible behaviours given the uncertainty in fracture data and other key factors like matrix-fracture transfer.
The results of this modeling work were used to formulate plans and recommendations for full-field modeling. A key conclusion derived from this study was that an effective single medium model would be adequate for full-field modeling of the subject reservoir. Work on the effective single medium full-field model is currently underway and the results-to-date are promising in terms of modeling reservoir behavior.
A New Simulation Grid Type is Demonstrated for the Giant Troll Oil and Gas Field
Authors: Vinje Jo , Nybø Roger , Grinestaff George 
Published: October 2011

Abstract
A new type of grid used in the dynamic simulation model of the giant Troll Field is presented. The grid consists of a stratigraphic and a horizontal layered part. Hence, it is named hybrid grid. The horizontal part encompasses the thin oil zone and a small distance into the gas cap and water zone, the rest of the grid follows the stratigraphy. The reason for choosing such a grid for the Troll Field is the dipping stratigraphic layering, a thin oil column, and the large area that the field covers. Another factor is the long horizontal wells that drain the oil. The horizontal grid has a high vertical resolution of 2 m to accurately capture the thin oil column, and for satisfactorily representing horizontal wells close to the fluid contacts. Above and below the horizontal grid the layers follow the stratigraphy to represent the geology with a minimum number of grid blocks. The paper shows why the hybrid grid is superior compared to other grid types for a gas field with a thin oil column, and covering a large area. The paper also describes how to build a hybrid grid, and the work processes for up-scaling and history matching the model. The new Troll model has currently replaced the 15 simulation models that previously were used to represent dynamically the Troll Field.
Reservoir Characterization, Fracture Mapping, and Well Placement Using a Suite of Logging-While-Drilling Images with Multiple Resolutions in a Marginal, Middle East Carbonate Reservoir
Authors: Al Daghar Khadija , Ihab Tarek , Sayed Raza , Abdelaal Atef , Ramos Luis , Chemali Roland , Aki Ahmet , Azzam Samer , Razek Omar Abdel 
Published: October 2011

Abstract
In a low-permeability Middle East carbonate reservoir, geologists, petrophysicists, and reservoir and drilling engineers had multiple requirements to optimally place the well, characterize and model fractures and faults, and evaluate the petrophysical attributes and cutoffs of the formation. A suite of logging-while-drilling (LWD) sensors was combined into a single bottomhole assembly (BHA) with the objective of acquiring the information needed to update the static model.
An integrated study was then performed using production logs, which led to an improved dynamic model within this sector of the reservoir. An additional objective was to evaluate the contribution from each sensor for future applications in this field, or in similar fields. Based on this assessment, a workflow was agreed upon for optimizing the petrophysical data acquisition program and conveyance methods. From a scientific point of view, the comparison of the various logs and images helped to better understand the response of the various sensor measurements for this particular field.
Improving Reservoir Characterisation and Simulation with Near Wellbore Modeling
Authors: Chandra V. , Hamdi H. , Corbett P. W. , Geiger S. 
Published: October 2011

Abstract
New reservoir characterisation methods are needed to integrate multi-scale exploration and development data, particularly at the interface between well and field models. In this paper we illustrate a novel workflow involving high resolution Near Wellbore Modeling (NWM), which allows us to accurately include seismic, wire-line data, FMI, and well core logs from multi-porosity reservoirs in field-scale reservoir simulations. We demonstrate that NWM improves reservoir characterization and production management. The workflow was applied to a realistic clastic reservoir with high variance at small scale and can also be extended for carbonate reservoirs. We have performed a number of sensitivities comparing conventional local grid refinement in the near wellbore region with that involving NWM and obtained a significant increase in the accuracy of reservoir characterization and the calibration of dynamic models. Centimetre-scale models, containing several million cells, representing the fine geological details of the near-wellbore region were constructed using available data from seismic, core, open-hole and production well-log suits. Sensitivities were performed using these high-resolution models to obtain regular grids with the best possible up-scaling. The resulting well models were imported into a field-scale simulation model to evaluate the dynamic behavior of the reservoir employing numerical well testing. Our results show that using NWM tools for reservoir modeling yields more precise flow calculations and improves our fundamental understanding of the interactions between the reservoir and the wellbore.
A Comprehensive Approach for Assessing the Impacts of Wettability on Oil Production in Carbonate Reservoirs
Authors: Faerstein Marcos , Couto Paulo , Alves José Luis 
Published: October 2011

Abstract
This paper discusses the impacts that rock wettability may have upon the production and recovery of oil with waterflooding in carbonate reservoirs and how it should be modeled. A broad review of the state of the art has been conducted surveying existing disagreements and knowledge gaps, basic definitions, as well as the correct understanding of the physical phenomena and identification of the characteristics of the various wettability scenarios.
Case studies conducted with a black oil reservoir simulator evaluated the impact of different wettability scenarios on oil production and recovery. A comprehensive approach considering all the parameters involved in the wettability modeling was applied to the case studies, showing how the behavior of the reservoir varies as a function of their wettability.
This paper shows how relative permeability and capillary pressure should be varied to correctly represent different wettability scenarios and consequently assess its impacts on oil production and recovery.
The case studies show that the evaluation of the volume of oil in the reservoir is impacted by wettability through the irreducible water saturation and primary drainage capillary pressure and must be considered in the analyses. In long term analyses, mixed-wet scenarios have a higher oil production and recovery. In medium and short term, the water-wet scenarios have the higher recovery, but in relation to oil production, these scenarios are negatively influenced by the smaller volume of oil in place.
The main contribution of this paper is the simultaneous analyses of all the parameters involved in the modeling of wettability showing how they impact the behavior of a reservoir. It shows how the parameters must be varied in a heterogeneous reservoir and how heterogeneity impacts the relevance of wettability in the studies.
Remaining Oil Saturation Study in Giant Oil Field: An Integrated Work Involving Laboratory and Log Measurements
Authors: El Din S. Serag , Kalam Zubair , Brahmakulam Jacob 
Published: October 2011

Abstract
As more and more fields mature in their production life cycle, EOR/IOR methods attain increasing significance. To plan these recovery methods optimally an accurate measure of the remaining hydrocarbon saturation is required to establish if there are sufficient hydrocarbons left in the reservoir to make a recovery process worthwhile. Integrating the state of the art Liquid Trapper coring technique and laboratory analysis on whole core and plugs reduce the uncertainty in this crucial reservoir parameter. New developments in dielectric logging techniques provide accurate remaining saturation answers with depth resolution of the scale of core plugs, for effective comparison and enhanced confidence on the answers.
The current study aims to evaluate the remaining oil saturation (ROS) after a water flood in 4 different wells located in a depleted zone of a Cretaceous carbonate reservoir in a giant field, onshore Abu Dhabi. This is the first time a multi-well study involving liquid trapper technique is conducted in the subject field with an objective of better capturing the reservoir heterogeneities and their possible impact on the ROS.
Laboratory measurements were conducted on reservoir core samples ranging from full diameter whole cores down to small plugs. The multi-scale analysis confirmed the variations in rock properties and the influence of heterogeneity on the reservoir properties, and ROS distribution. Petrophysical Groups (PG) were also defined and the final ROS values were distributed per PGs. ROS values from cores were compared with the continuous log measurement from the new multi frequency dielectric tool, deployed for the first time in the country. The array sensors of the tool make the borehole correction robust while the dispersion analysis of the multi-frequency data provides saturation answers unaffected by pore fluid salinity and carbonate texture. The uncertainty in ROS measurements and best practices for future is also discussed.
Production Optimization Considering Interaction between Reservoirs and Constrained Surface Facilities
Authors: Cotrim Henrique A. , von Hohendorff João C. , Schiozer Denis J. 
Published: October 2011

Abstract
Integrated asset models (IAM) are often necessary to analyze properly the pressure interaction between reservoirs and a constrained surface facility network and to predict the behavior of several fields, which may have different fluid compositions, sharing a common surface facility. In this study, we describe a field development project improvement due to production rate management using a well known approach for coupling a commercial reservoir simulator and a simplified surface network model. The approach technique was tested using a real-based case of two offshore fields, one of gas condensate and the other one of light oil, with a gas production constraint due to the gas pipeline capacity. At present work, the two independent reservoir models were controlled simultaneously by the coupling tool and the well production rates allocated at each iteration by the management algorithm. The coupled system gives a significantly higher oil production and NPV than the standalone simulation did only by well production rate management based on GOR (gas-oil ratio). In thirty years production forecast, considering the surface gas constraint, there was a significant increase on NPV and nearly the same recovery factor. In other words, it was obtained an excellent improvement on the overall project due to revenue anticipation using the well rates from management algorithm.
The Role of Tire Overturning Moment in Steering
Authors: Blue D. W. 
Published: October 2011

Abstract
Tire overturning moment measurements have traditionally been used primarily for rollover threshold analysis and have often been ignored for linear range maneuvers. This paper explains how overturning moment is related to aligning torque for a tire under tractive force. This relationship can be used to develop a better understanding of tire properties necessary to achieve better steering refinement. A free rolling overturning moment measurement is shown to provide useful information for aligning torque performance. For example, force and moment test results are shown to illustrate the concepts.
Mechanics of Bend-Over-Sheave (Shoeshine) Fatigue Testing of Cord-Rubber Laminates
Authors: van Bogaert P. , van Bogaert S. 
Published: October 2011

Abstract
The Bend-Over-Sheave test is used for screening reinforcement cords used in tires, especially on fatigue interply delamination as well as rubber-fabric and rubber-cord adhesion degradation. The typical cyclic load of tension-tension of the sidewalls or tension-compression of the belt can be achieved by the proper definition of two-ply laminates bent over a sheave. The objective of this paper is to define relevant fatigue test conditions that can predict the performance of new materials. A finite element model of the Bend-Over-Sheave test configuration is presented and shows that, for the test arrangements studied in this paper, flanged wheels should be used to prevent lateral buckling in the compressed cords. Besides, a simplified model enables us to determine the different factors that have significant effect on the strain levels in the cords. The material of the cords, the rubber hardness (“Shore”), and the sample manufacturing process are shown to have an influence on the specimen strain levels. The test conditions, i.e., the sheave radius, the traction force, and the contact angle between the sheave and the sample, also affect the behavior specimen strain levels. On the other hand, if the sample length is higher than a certain value, it is shown not to have a significant effect on the results.
Parallel Computing for Tire Simulations
Authors: Surendranath H. , Dunbar M. 
Published: October 2011

Abstract
Over the last few decades, finite element analysis has become an integral part of the overall tire design process. Engineers need to perform a number of different simulations to evaluate new designs and study the effect of proposed design changes. However, tires pose formidable simulation challenges due to the presence of highly nonlinear rubber compounds, embedded reinforcements, complex tread geometries, rolling contact, and large deformations. Accurate simulation requires careful consideration of these factors, resulting in the extensive turnaround time, often times prolonging the design cycle. Therefore, it is extremely critical to explore means to reduce the turnaround time while producing reliable results.
Compute clusters have recently become a cost effective means to perform high performance computing (HPC). Distributed memory parallel solvers designed to take advantage of compute clusters have become increasingly popular. In this paper, we examine the use of HPC for various tire simulations and demonstrate how it can significantly reduce simulation turnaround time. Abaqus/Standard is used for routine tire simulations like footprint and steady state rolling. Abaqus/Explicit is used for transient rolling and hydroplaning simulations. The run times and scaling data corresponding to models of various sizes and complexity are presented.
Investigations on Rolling Resistance of Nanocomposite Based Passenger Car Radial Tyre Tread Compounds Using Simulation Technique
Authors: Ghosh S. , Sengupta R.A. , Heinrich G. 
Published: October 2011

Abstract
Tyre rolling resistance is a key performance index in the tyre industry that addresses the environmental concern. Reduction of tyre rolling resistance is a major challenge so as to lower the fuel consumption, which could be achieved by changing both design as well as compound formulation. In this paper, rolling resistance of 205/60R15 as well as 155/70R14 passenger car radial tyre with nanocomposite based tread compounds were evaluated using finite element (FE) analysis. The energy dissipation in the tyre was evaluated using the product of elastic strain energy and the loss tangent of materials through post processing using a rolling resistance code. The elastic strain energy was obtained through steady state rolling simulation of tyre using Abaqus software and the loss tangent was measured in the laboratory by viscoanalyzer. A good correlation of rolling resistance was observed between simulation and experimental results. Nanocomposites used in this study were prepared based on solution styrene butadiene rubber and polybutadiene rubber blends with either organoclay and carbon black or organoclay and silica dual fillers. Carboxylated nitrile rubber, a polar rubber, was used as compatibilizer to facilitate the clay dispersion in rubber matrix. Compared to general carbon black or silica tread compounds, substantial improvement of rolling resistance was predicted by FE simulation with nanocomposite based tread compounds containing dual fillers organoclay-carbon black or organoclay-silica.