bluuebunny/crossref_metadata_2025_split huggingface dataset:
Artificial Neural Networks Applied to the Operation of VGO Hydrotreaters
Authors: Lopez R. , Perez J. R. , Dassori C. G. , Ranson A. 
Published: December 2007

Abstract
This study introduces an accurate, generalized method based on a three-layered perceptron artificial neural network (ANN) trained to estimate the continuous operation of a vacuum gas oil hydrotreater. The ANN models predict the fractional composition of paraffins, naphthenes, and aromatics distribution (mono, di, tri and tetra aromatics) contained in a vacuum gas oil (VGO) mixture. Moreover, ANN models were built to simulate the behavior of several process variables such as product flowrate, average reactor temperature and product quality (sulfur content, API gravity, TBP50, metals content, and refractive index).
VGOs proceeding from commercial hydrotreaters were employed to illustrate the use of ANN models to estimate the VGO composition in a very simple manner with no need for knowledge of the system. The artificial neural net models use API gravity, TBP50 and the refractive index of the desired vacuum gas oil to be studied.
These empirical models were tested on experimental data not used during training showing an average error of 0.5 % in the prediction of VGO paraffins, naphthenes and total aromatics content, which is an outstanding performance compared with traditional correlations proposed in the literature.
The hydrotreater reactor ANN models were compared against process data collected from the CRP-Amuay refinery data acquisition system. The results using the ANN model to estimate the reactor EIT (Equivalent isothermal temperature) indicate an average error of 4 °F. Additionally, the product sulfur content prediction reports an average error equal to 6 wt%.
The Use of Fuzzy Mathematics of Finance: Risk Evaluation in Petroleum Development
Authors: de Salvo Castro Antônio Orestes , Martins Fereira Filho Virgilio José 
Published: December 2007

Abstract
• In general, most capital budgeting problems deals with future and often uncertain data. To cope with this uncertainty, fuzzy sets theory has been applied to traditional deterministic approaches by replacing uncertain data with fuzzy numbers. In this paper the bases of The Fuzzy Mathematics of Finance, to model the uncertainties of data inputs is presented, providing anapproach to risk analysis. The goal is to capture and quantify the qualitative information of the project coordinators using linguistics variables and modelthe uncertain cash flow and discount rates as triangular fuzzy numbers. Anexample of fuzzy cash flows and fuzzy resultant net present value (NPV) is computed from the model. Finally, a fuzzy project selection is performed by applying different dominance rules and a comprehensive numerical example is present.
Integration of 3D Seismic and Production Data in Secondary Recovery Analysis, Puesto Hernandez Field, Neuquén, Argentina
Authors: Montagna Aldo , Yañez Pablo Paez , Groba Cristian , Cerutti Andrés 
Published: December 2007

Abstract
The object of this work was to optimize a waterflood project in a highly complex structural-stratigraphic area. A geophysicist, two waterflood-monitoring engineers and a numerical simulation specialist made up the multidisciplinary team created for the project.
The goal was to explain the low response to water injection in the subject area, i.e. the injection well behavior (variation in the admitted volume, overpressurization, etc.), and the corresponding shortage in production wells.
The information used for this study consisted in 3D seismic data, interpreted well logs, correlation, transient pressure tests, production and injection history, hydraulic connectivity analysis and previous structural interpretations. A radioactive tracer test was also conducted.
Seismic cross-section were developed between wells in order to detect structural and stratigraphic lineaments. Then, a seismic attribute analysis was performed. The reflection strength and the amplitude attribute reflected clearly the thickness loss northward and the deterioration of the petrophysical properties toward the east. The instantaneous phase attribute was used to interpret the structural frame but no significant results were obtained. A reliable correlation between petrophysical information and seismic data was achieved.
After defining the structural – stratigraphic frame, the information above was related to the production and injection history of the area. Some old build up and fall off tests were reviewed in order to confirm the existence of faults and petrophysical changes.
Based on this analysis, some proposals were drawn to improve 1the production and injection behavior of the pattern, namely, horizontal drilling from existing vertical wells, acid treatment, hydraulic fracturing and the drilling of a horizontal well in an unswept area.
The reservoir water saturation distribution was evaluated for each proposal using a numerical simulation model and a cost-effective analysis of the proposals was carried out.
Natural Waterflooding, Campo La Peña
Authors: Luis Rivero Jose , Navia Walter 
Published: December 2007

Abstract
Waterflooding is a secondary recovery method widely used in the oil industry implemented with the purpose of increasing additional oil recovery from oil reservoirs. Traditionally the waterflooding projects are implemented by means of injecting water through water injector wells in order to maintain or improve the reservoir pressure and to sweep the oil towards the producer wells.
The purpose of this work is to present a novel waterflooding alternative called natural waterflooding. This natural waterflooding method attempts to use the water and energy from a higher pressure reservoir to a lower pressure reservoir. The natural waterflooding method will be implemented to La Peña reservoir of La Peña Field throughout a crossflow system of the water coming from Bolivar reservoir of the same field. In this field La Peña reservoir (upper reservoir) is being depleted naturally and we want to avoid the pressure to fall too far below the bubble point. At the same time the waterflood will be used to sweep the oil from the lower parts of the reservoir toward the wells located in the upper part of the reservoir. The Bolivar reservoir (lower reservoir) has a strong water drive system that has sustained the reservoir pressure in the order of 150 psi below the initial reservoir pressure (3750 psi) for more than 20 years of explotation. Currently exists 1500 psi of pressure difference between these two reservoirs.
In this work we describe the overall project and the several stages to be tested before the full field implementation. We also include the favorable expected economic impact of this method compared to the classic waterflooding. At this moment the laboratory tests have been performed and are explained. Nodal analysis applied to the water production system of the Bolivar reservoir and to the water injection of the La Peña reservoir was performed in order to determine the water rate that will enter into La Peña reservoir. Also the varation of the rate due to the pressure increase in La Peña reservoir with time is considered. Currently we are at the pilot project stage implementation. Field work consists in the workover for the pilot project and is the next operating step. Field tests are part of the next steps and their design are described in detail.
El Tordillo Reservoir Static Characterization Study: El Tordillo Field, Argentina
Authors: Taboada R. , Condat P. , Corsini V. , Mir E. , Conti J. , Fortunato G. , Villivar O. , List D. , Stancel S. , Jones L. 
Published: December 2007

Abstract
The El Tordillo Field is located in the San Jorge Basin, in southern Argentina, and is operated by Tecpetrol S.A.
Realizing this study requires a complex, multi-disciplined approach that allows UTE El Tordillo to describe the reservoir and to develop an appropriate plan to more efficiently use manpower in operating and managing this highly complex reservoir. An essential step toward this goal is developing an integrated structural and stratigraphic model of the reservoirs in the field. These tasks comprise: creating a "living" integrated digital database for the geological, geophysical and mechanical data; making the stratigraphic correlation; identifying all seismically mappable faults and defining the structure of key horizons.
Results of these analyses include the following:
The Reservoirs Characterization Study produced a digital model that is an accurate and detailed 3-D structure and stratigraphic picture of the entire reservoir volume. Specifically, this model provides a consistent, field-wide, stratigraphic correlation of key horizons that were interpreted using with a high level of integration of geologic and geophysical data. The maps show the field wide distribution, structure and well test results for the 241 individual reservoir sands. Another direct benefit of this study is an enhanced understanding of the 3-dimensional distribution of reservoir units and the controls on reservoir quality. These insights will lead to a better understanding of the production compartmentalization of the reservoir and will help UTE El Tordillo optimize and prioritize development and secondary recovery projects.
GRE Composite-Lined Tubular Products in Corrosive Service: A Study in Workover Economics
Authors: Ross Kenneth 
Published: December 2007

Abstract
This paper is a two-part discussion describing Glass Reinforced Epoxy composite linings manufactured and installed in oilfield tubular goods where the material functions as a barrier to corrosion. The paper first focuses on GRE composites in terms of effectiveness and product life compared with less-costly corrosion solutions (such as internal plastic coatings (IPC) and thermoplastic materials like HDPE and PVC). Next, actual case history economic data is presented to qualify the use of Glass Reinforced Epoxy-lined tubular goods over IPC for corrosive seawater injection service in the North Sea. These data are then extrapolated to construct a similar economic model based on workover costs in the Permian basin of West Texas. Additionally, net present value (NPV) analysis can be used to illustrate the saving s in long term operating costs over the life of the project.
Simultaneous Determination of Reservoir Pressure and Initial Fluid-in-Place From Production Data and Flowing Bottom Hole Pressure -- Application
Authors: Wang Shie-Way 
Published: December 2007

Abstract
This work presents procedures on how to apply a newly developed method to simultaneously determine the average reservoir pressure and initial fluid in place using surface production data and flowing bottom hole pressure. This new method is derived from a combination of a generalized material balance formulation and pseudo steady state theory. Reservoir simulation was used to generate production history and flowing bottom hole pressure via hydraulic tables, which were used to calculate average reservoir pressure and initial fluid in place in order to validate the accuracy of this new method. Five examples were investigated for production with vertical and horizontal wells in oil and gas reservoirs at constant rate or constant flowing bottom hole pressure. Calculated initial-fluid-in-place and average reservoir pressures agree very well with that derived from reservoir simulation. This new method is useful in analyzing surface production data in the following conditions: (1) reservoirs significantly lack data, (2) buildup tests are inconclusive in determining average pressure, (3) buildup tests are expensive or difficult to run such as wells in tight and over-pressured reservoirs or with subsea completion.
Numerical Well Test Analysis of Stress-Sensitive Reservoirs
Authors: Pinzon Claudia L. , Chen Her-Yuan , Teufel Lawrence W. 
Published: December 2007

Abstract
Two issues are addressed in this study: (1) What are the characteristics of the well testing responses if the reservoir is stress-sensitive? (2) How accurate are the well-test-estimated permeability and drainage volume using the existing techniques (non-stress-sensitive assumption) if the reservoir is stress-sensitive? We study the above issues using a fully coupled fluid-flow/geomechanical simulator. Numerical transient pressure and reservoir limit tests are presented to illustrate the differences between cases of (i) constant reservoir properties and (ii) stress-dependent reservoir properties. Case (ii) assumes that the permeability is a function of effective stress, which in turn is constantly changing during the well-test period. Characteristics of pressure derivatives are also presented to extend current well-test diagnosis techniques into stress-sensitive reservoirs. The total (or system) compressibility is shown to be extremely critical in the estimation of the drainage area and volume. An all-purpose "rock compressibility" is proposed to represent the rock compressibility term in the total compressibility.
Alteration of Reservoir Wettability Due to Asphaltene Deposition in Rhourd-Nouss Sud Est Field, Algeria
Authors: Amroun Hacene , Tiab Djebbar 
Published: December 2007

Abstract
Wettability is an important factor in a number of petroleum production processes including secondary recovery and tertiary recovery operations. In fact these processes in the later life of the reservoir are more or less controlled by the wetting properties of the rock and fluids present in it.
The role of Asphaltene deposition on the wettability is investigated in this research work. It has been observed that the Asphaltene deposition has a strong role in wettability reversal. Among many factors, the high molecular weight with, polar fraction of crude oils, including the asphaltenes, are considered to be the primary wettability altering agents. Considering the complexity of reservoir rocks and crud oils, each reservoir system is a specific case and its behavior can only be confirmed through experimental work.
In this paper the role of asphaltene and its deposition in altering the reservoir wettability of Rhourd-Nouss Sud Est (RNSE Algeria) field is presented. It was found that the samples of RNSE are of intermediate wettability and are very close to neutral wettability. At higher concentrations of asphaltenes in the crude oil the rocks have greater tendency to become neutral-wet systems.
Understanding the Effects of Reservoir and Operating Parameters on Tight-Gas Production Decline
Authors: Chen Her-Yuan , Teufel Lawrence W. 
Published: December 2007

Abstract
This paper presents a systematic analysis of production decline of tight-gas wells. The roles of fluid-reservoir and operating parameters on the flow rate, decline rate, decline exponent, productivity factor, ultimate recovery, and recovery factor are identified based on seven performance indicators. These seven indicators can be obtained easily by type-curve matching of production data (inverse study) or by simple computation using the presented equations (forward study). An action-reaction chart is constructed to provide a "quick-look" for the impacts (benefits or/and trade-offs) of actions (changes in reservoir/operating parameters) on the seven types of well performance (reactions). Among all the actions considered, well-stimulation and well-spacing result in the most complicated reactions. They are also the two engineering issues most pertinent to tight-gas developments. Their impacts are demonstrated by numerical examples.
Drainage Shape and Size of a Vertically-Fractured Tight-Gas Well
Authors: Alzate Guillermo A. , Chen Her-Yuan , Teufel Lawrence W. 
Published: December 2007

Abstract
This paper presents a systematic simulation study of a tight-gas, vertically-fractured well aimed to describe the evolution of drainage shape and size with time. The drainage shape is described in terms of the drainage-aspect-ratio, the ratio of the length to width of the specified isopressure line. The drainage size is described in terms of the drainage-area-ratio, the ratio of the area for the specified isopressure line to the well spacing area. The shape and size of a drainage area are determined numerically for a specified isopressure line as functions of dimensionless fracture conductivity (1 ≤ FCD ≤ 1,000), fracture half-length (94 to 840 ft), permeability level, permeability anisotropy, and time. Knowledge of the evolution of drainage size and shape with time and their long-term behavior are extremely important for planning infill drilling activities, either for choosing new infill well locations or modifying well spacing/pattern. An example is given to show how to estimate drainage shape and size based on the results presented here.
Geostatistical Integration of Rock Physics, Seismic Amplitudes and Geological Models in North-Sea Turbidite Systems
Authors: Caers Jef , Avseth Per , Mukerji Tapan 
Published: December 2007

Abstract
Turbidite systems are complex heterogeneous siliciclastic deposits calling for a new approach to geophysical and geostatistical reservoir characterization. The aim of this paper is to demonstrate the integration of seismic amplitude and rock physics data into realistic geological scenarios using a novel geostatistical approach. Avseth (2000, 2001 with others) presented an integrated rock physics/seismic inversion approach to predict seismic facies within the Glitne Field reservoir, North Sea. The outcome of this work is a seismic derived conditional probability of facies. We provide a geostatistal methodology for integrating this large-scale probability model with smaller scale geological models consisting of channel complexes typical for known turbidite systems around the world.
Halfdan: Developing Non-Structurally Trapped Oil in North Sea Chalk
Authors: Albrechtsen T. , Andersen S. J. , Dons T. , Engstrem F. , Jergensen O. , Sørensen F. W. 
Published: December 2007

Abstract
Mæsk Olie og Gas AS has as operator for the Danish Underground Consortium (DUC) discovered and initiated the development of the Halfdan accumulation located in the southern part of the Danish North Sea. The accumulation comprises oil and gas in a low permeability chalk reservoir located outside structural closure.
This paper describes how the phased, fast track development of Halfdan was planned and executed while testing a new concept for constructing an aligned sweep pattern.
Tilted oil-water and gas-oil contacts across the Halfdan area are indicative of non-equilibrium conditions. The nonstructural trapping in the Halfdan area is provided by a combination of up dip thinning of the hydrocarbon bearing section, late structural tilting and the slow re-adjustment caused by the low permeability.
Accelerated and stepwise development was pursued to allow continuous optimisation of the development in light of the significant uncertainties associated with the fluid distribution and reservoir production characteristics. Appraisal drilling from a template and tie-back of the appraisal wells to temporary production facilities via the drilling rig and early deployed pipelines enabled production from the Halfdan 10 months after finalising the discovery well. Furthermore, a temporary water injection package installed on the drilling rig enabled evaluation of water injection before the installation of permanent facilities including determination of displacement efficiency, fracturing pressure and induced fracture orientation. Halfdan was produced through permanent facilities less than 18 months after finalising the discovery well.
Reservoir Modeling Using Multiple-Point Statistics
Authors: Strebelle Sebastien B. , Journel Andre G. 
Published: December 2007

Abstract
Two approaches are traditionally used to build numerical models for facies distributions within a reservoir. Pixel-based techniques aim at generating simulated realizations that honor the well data values, and reproduce a given variogram which models two-point spatial correlation. However, because the variogram cannot look at spatial continuity between more than two locations at a time, pixel-based algorithms give poor representations of the actual facies geometries. In contrast, object-based techniques allow reproducing crisp geometries, but the conditioning on well data requires iterative "trial-and-error" corrections, which can be time-consuming, particularly when the data are dense with regard to the average object size. This paper presents a new approach that combines the easy conditioning of pixel-based algorithms with the ability to reproduce "shapes" of object-based techniques, without being too time and memory demanding.
In this new approach, the complex geological structures expected to be present in the reservoir are characterized by multiple-point statistics, which express joint variability at many more than two locations at a time. Such multiple-point statistics cannot be inferred from typically sparse well data but could be read from training images depicting the expected subsurface heterogeneities. A training image need not carry any locally accurate information on the reservoir; it need only reflect a prior stationary geological/structural concept. Thus training images can be generated by object-based algorithms freed of the constraint of data conditioning. The multiple-point statistics inferred from the training image(s) are then exported to the reservoir model, where they are anchored to the well data using a pixel-based sequential simulation algorithm.
This algorithm is tested for the simulation of a turbidite system where flow is controlled by meandering channels with cross-bedding. The training image reflecting the channel patterns is an unconditional realization generated by an object-based algorithm. The final simulated numerical models reproduce these channel patterns, and honor exactly all well data values at their locations. The methodology proposed appears to be practical, general, and fast.
Assessing the Oil Water Contact in Haradh Arab-D
Authors: Stenger B. A. , Pham T. R. , Al-Sahhaf A. A. , Al-Muhaish A. S. 
Published: December 2007

Abstract
Haradh forms the southernmost part of the super giant Ghawar oil field located about 80 km (50 miles) onshore from the Arabian Gulf, in the Eastern Province, Kingdom of Saudi Arabia (Fig. 1).
A major feature of the Ghawar field is its tilted Original Oil Water Contact (OOWC), getting shallower from North to South Ghawar at an average gradient of 0.36 m (1.2 ft) per km. In Haradh, the OOWC displays also a large but localized west-to-east component.
Understanding the OOWC tilt mechanisms is vital since it will improve the effectiveness of the on-going Oil-Water Contact (OWC) delineation program. This will result in better placement of future producers and injectors, which in turn will reduce the cost of future developments.