bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zonal Allocation and Increased Production Opportunities Using Data Mining in Kern River
Authors: Popa Carrie , Popa Andrei , Cover Andrew 
Published: December 2007

AbstractThis paper presents a fast and effective methodology to estimate zonal allocation for commingled producers in a multilayer reservoir using minimal, readily available data (well completion, historical production, sand depths, and location data). A set of data mining tools including regression, neural networks, and fuzzy logic was used to identify candidates for remedial work and the corresponding production increase expected. This approach was applied and executed in a portion of the Kern River field in California with very promising preliminary results.
Sand Production Prediction: A New Set of Criteria for Modeling Based on Large-Scale Transient Experiments and Numerical Investigation
Authors: Nouri Alireza , Vaziri Hans , Belhaj Hadi , Islam Rafiqul 
Published: December 2007

Abstract
Using novel physical model experiments and numerical analyses, a set of criteria are proposed that can be used to determine the onset of sanding and its severity in terms of rate and duration.
Experiments on large-scale hollow cylinder specimens were conducted involving real time sand production measurement under various conditions. Synthetic sandstone was used in the experiments whose strength properties were comprehensively determined. A numerical approach was used for simulating the proposed experiments. The material behaviour was simulated using an elasto-plastic stress-strain relationship. The model simulates interaction between fluid flow and mechanical deformation of the medium in predicting sand production. The criteria considered for sanding are more comprehensive than conventionally used and included modeling strain softening of the material accompanied with shear bands formation as well as tensile failure. In the post disaggregation phase, additional features are considered including allowing for the removal of the disaggregated material and making the necessary adjustments to the size and properties of the domain under consideration. Hence, the model is considered to be suitable for time-dependent analysis of the rock as it undergoes disaggregation and production induced by depletion, drawdown, and water-cut. By relating the sand rate to production over the life of a field, the tool can be used in assisting with the completion and operation design of the wells.
The model shows good agreement with experimental results in terms of rock deformation and sand rate. It predicted the onset of shear failure and the subsequent strain softening initiated from the cavity face and propagated inside the medium. Strain softening proved to be the main mechanism for material disaggregation. The good agreement between the numerical and experimental results under comprehensive and complex conditions bodes well for its field applications.
A Combined Geological, Geophysical and Rock Mechanics Approach to Naturally Fractured Reservoir Characterization and Its Applications
Authors: Shen Feng , Li Shuiquan 
Published: December 2007

Abstract
In this paper, we present a combined geological, geophysical and rock mechanics approach to natural fractured reservoir characterization. The local structure entropy analysis on 3D seismic data is used to detect distributions of fault and sub-fault systems. The curvature attribute along with modeled strain and stress field, constrained with the log data measuring P- and S-wave velocities and rock density and the inverted elastic modulus from pre-stack seismic data, reveal effects of the geological structure, bed thickness and lithology on fracturability of the reservoir layer. These analyses quantify the relationships between the geologic factors and rock fracturability and describe physically the weighting factors for geologic parameters in controlling the rock fracturing. The comparison of the seismic azimuthal analysis results to these of geological and rock mechanics modeling provides an opportunity to verify whether the seismic anisotropy derived from seismic data is caused by structure related natural fracture patterns or by other mechanisms. The consistency among different techniques provides the confidence in the interpretation of the distribution of fractures induced by structures. If azimuthal seismic attribute data can be combined, the application of this procedure results in the development of the fracture connectivity anisotropy by considering relationships between the present and palaeo-stress fields. In addition, the scale depend analysis technique in this approach can improve the ability to identify the distribution of fractures with multiple length scales. In this paper, case studies are used to illustrate applications of these technologies and their efficiency.
Compositional Modeling by the Combined Discontinuous Galerkin and Mixed Methods
Authors: Hoteit H. , Firoozabadi A. 
Published: December 2007

Abstract
In this work, we present a new numerical procedure that combines the mixed finite element (MFE) and the discontinuous Galerkin (DG) methods. This numerical scheme is used to solve the highly nonlinear coupled equations that describe the flow processes in homogeneous and heterogeneous media with mass transfer between the phases. The MFE method is used to approximate the phase velocity based on the pressure (more precisely average pressure) at the interface between the nodes. This approach conserves the mass locally at the element level and guarantees the continuity of the total flux across the interfaces. The DG method is used to solve the flow equations which are generally convection dominated. The DG method associated with suitable slope limiters can capture sharp gradients in the solution without creating spurious oscillations. We present several numerical examples in homogeneous and heterogeneous media that demonstrate the superiority of our method to the finite difference (FD) approach. Our proposed MFE-DG method becomes orders of magnitude faster than the FD method for a desired accuracy in 2D.
Simulation-Based EOR Evaluation of a North Sea Field
Authors: Skinner Roger C , Jerauld Gary R. , Bush Michael D. 
Published: December 2007

Abstract
A North Sea oil field was evaluated for continued gas injection for an EOR scheme. Two key aspects of the evaluation used genetic algorithm optimization to support the workflow. The initial application was in determining the range of model variables that equally well matched history and are known to impact EOR performance. The second application was to generate pseudo's to translate fine scale sector model simulation results to enable full field EOR evaluation. The genetic algorithm approach to the history match enables any clusters of variables that together match history to be defined, as well as their individual sensitivity in achieving a match. The outcome is a range of possible models that fit the historical data equally well, which then define a range for predicted EOR performance. The results of this exercise will be presented. The pseudo application enabled the rapid up-scaling of the fine scale sector model results such that they could be confidently applied directly in full field model compositional simulation. The good up-scaling match that was achieved will be presented. The overall outcome was a rapid evaluation of EOR performance in the field together with the expected uncertainty ranges.
The genetic algorithm technique used is very general and can therefore be applied to any problem that has a quantitative measure of success that is dependant on varying input parameters. The challenge is determining the parameters than control performance along with their uncertainty rage and in setting up the software to automatically compute at appropriate measure of success which can be optimized. The generation of multiple variable sets that equally well fit the history data enables a range in EOR prediction to be generated rather than the usual approach of using one history matched base case or performing monte carlo analysis unconstrainted to history. The up-scaling of fine scale simulation results of a complex process, such as EOR, is difficult. The presented technique automates the up-scaling, enabling multiple scenarios to be evaluated
Phase Equilibrium between Gas Condensate and Brine at HT/HP Conditions
Authors: Pedersen K. S. , Milter J. 
Published: December 2007

Abstract
Petroleum reservoir fluids are often produced together with formation water. The mutual solubility between water and hydrocarbons is somewhat affected by the salt contained in the formation water. The paper presents phase equilibrium data for the mutual solubility of brine and a gas condensate mixture at temperatures ranging from 35 °C to 200 °C and pressures of 700 bar and 1000 bar. The phase compositions are compared with compositions measured at the same conditions for the same gas condensate mixed with pure water. The experimental data are modeled using the SRK and PR equations with the non-classical mixing rule of Huron and Vidal. The salt ions are treated as hypothetical molecules having critical properties close to those of high boiling liquid hydrate inhibitors. The model takes into consideration possible association of salt ions and water molecules in the water phase. The simulations results are in good agreement with the experimental data even at high pressure and high temperatures.
Integrated Approach for Optimization of Field Development Portfolios in Complex Production Systems
Authors: Jacobs Richard A. 
Published: December 2007

AbstractThis work presents general steps, criteria and information tools to ensure consistent treatment of investment proposals and availability of key information when optimizing investment portfolios in complex production systems. The approach considers facilities and production related cash flows separately, and uses them as building blocks to describe the cash flows of individual projects, local field development plans, and the regional or corporate portfolios.
Multiscale Flow and Transport in Highly Heterogeneous Carbonates
Authors: Zhang Liying , Bryant Steven L. , Jennings James W. , Arbogast Todd J. , Paruchuri Ramoj 
Published: December 2007

Abstract
Large-scale (cm and greater) heterogeneities raise both practical and theoretical problems for understanding fluid flow through rocks that contain them. Standard sampling methods such as thin sections, core plugs, and even whole core are at a scale too small to resolve these heterogeneities, and direct measurement of flow properties is not straightforward. Moreover it is not obvious what physical formulism (e.g., Darcy's law, Forchheimer's Law, Stokes flow) is appropriate for modeling flow or interpreting flow measurements, nor is it clear that traditional homogenization approaches (e.g., effective medium theory, renormalization, dual-porosity) are applicable in such systems. We report simple measurements on a large 25 cm diameter by 36 cm high sample of Cretaceous carbonate containing centimeter-scale vugs, and compare them to flow fields computed from high-resolution CT images of the same sample. These computations use a single-physics Darcy-flow model. We also compute passive tracer transport in the same model to evaluate preferential flow paths within the rock. The direct computations are based on a porosity grid extracted from a set of CT images (512 × 512 × 240 pixels, 0.5 mm resolution) of the large sample. We also use the single-physics model to estimate the length scale of connections between vugs in this sample. The results demonstrate the need for upscaling methods that preserve connectivity of features in highly heterogeneous rocks.
Problems with the Elicitation of Uncertainty
Authors: Welsh M. B. , Begg S. H. , Bratvold R. B. , Lee M. D. 
Published: December 2007

Abstract
The Oil and Gas industry has a poor record when it comes to accurately assessing uncertainties. An assessment of the risks that arise from these uncertainties is a major factor influencing investment decisions in the O&G industry. Thus, throughout the industry, experts’ understanding of the probabilities of uncertain events are elicited via a range of methods. However, industry sources continue to report ‘surprise’ values (outside the P(80) range) far more often than the 20% indicated by this interval. This suggests problems in the elicitation process: either experts’ beliefs do not capture the distributions they are attempting to define or the processes used in the industry are failing to elicit the experts’ subjective probability distributions (SPDs) accurately.
The authors discuss the ways in which experts’ subjective beliefs about the probability of events are commonly elicited in the industry, and the biases expected to be observed therein, in light of psychological findings and theories of decision-making. Special note is made of the limitations imposed on decision-making by the nature of human short-term memory and predictable biases resulting from reliance on heuristic (rule-of-thumb) reasoning techniques.
The results of an experiment comparing two commonly used elicitation techniques with one, designed by the authors, which utilizes heuristic reasoning as a strength rather than a weakness, are presented and discussed. Accuracy, both in terms of subjective and objective measures, was improved on our experimental tasks by use of the new, More-or-Less Elicitation (MOLE) technique over both of the currently used methods. We conclude that an approach to elicitation that recognizes the tendency of people to use heuristic reasoning, rather than forces them to reason in probabilistic, non-intuitive ways, may yield superior results.
Finally, we discuss possible refinements to the MOLE process and further research required to elucidate the impacts of various biases on elicited distributions.
Validation of Clustering of Fractures in Discrete Fracture Network Model by Using Fracture Density Distributions along Boreholes
Authors: Tamagawa T. , Tezuka K. 
Published: December 2007

Abstract
This study reports a procedure for validating a reliability of a location distribution of fractures in highly populated portions (clusters) of a constructed discrete fracture network (DFN) model. In the procedure, we focus on a relationship between a fracture density distribution along boreholes and spatial extents of clusters of fractures in a DFN model. The numerical experiments show that a shape of a fracture density distribution function evaluated using fractures crossing boreholes mainly depends on a location distribution of fractures, and is less affected by a size distribution and an orientation distribution of fractures.
The DFN model is constructed by the procedure we had proposed previously. At the procedure, geostatistics method is used for predicting extents of clusters of fractures. However, it is pointed out that the extents of clusters have uncertainty due to the prediction by using only the observed locations of fractures along boreholes. This uncertainty reduces a reliability of a constructed DFN model.
To meet the issue, the fracture density distributions along boreholes are calculated for constructed DFN models with different extents of clusters and compared with the observations. Through the studies, it is confirmed that the fracture density distributions along boreholes are useful to constrain the uncertainty of the extents of the clusters and that the optimum extent of the cluster can be extracted by focusing the fracture density distribution along boreholes. Additionally, fluid flow behaviors of the constructed DFN model with the optimum extents of clusters is verified by flow simulations.
Application of MJPs in Oil&Gas Fields
Authors: Andreussi P. , Ansiati A. , Faluomi V. , Senna S. , Sodini S. , Dellarole E. , Battaia C. , Guaita P. 
Published: December 2007

Abstract
ENI E&P in 1993 launched an R&D project on production boosting using multiphase jet pumps. In these devices a high pressure oil or gas well can be used to enhance both the production and the total recovery from a depleted well. The multiphase ejector is characterized by a simple design, absence of moving parts and small dimensions, coupled with a high degree of reliability and low cost. The main disadvantages related to the use of multiphase ejectors are due to the lack of reliable design methods and to the sharp decrease of the performance when operative conditions change.
In the last three years the ejector technology can be considered a standard for ENI resulted in several successful installations worldwide: -West Africa (onshore oil wells)-GOM (offshore, condensate gas )-Italy and Mediterranean Sea (onshore and offshore, wet and dry gases)
In the present work a status of these installations is reported, pointing out the following main items: -design and installation peculiarities-predicted and measured performances-optimisation actions performed during the considered period
The results of this review have been used to identify the new strategies on ejector design and operability, which will be also reported. In particular, new design to increase productivity and component operability life is described, together with laboratory test results
Portfolio Management Using Questionable Quality Data
Authors: DuBois James R. 
Published: December 2007

AbstractMany, if not all portfolio managers spend a great deal of time worrying about the quality of their economic input data. These concerns cover the gamut from systemic over or under estimation, to project or region specific bias, to simple sloppy and inconsistent data gathering. Many postpone initiating advanced decision making techniques "until the data are in better shape". However, investment decision data quality rarely improves substantially until that data starts being used consistently, systematically, and seriously.How then are we initiate use of advanced decision making techniques if we don't trust the data? Business decisions are made every day, using the data that is available at the time. If we think of Portfolio Management and Optimization as techniques to improve the quality of our decisions, instead of as ways to find "the right answer", we can begin to use these techniques to improve those decisions in spite of reservations we may have about the quality of data currently at hand. Once a system is in place and functioning, data quality improvement measures can start to take hold with sufficient feedback to guide the process.In this paper we will investigate ways to use Portfolio Management and Optimization techniques to improve the quality of decisions being made even if the data used is questionable. We will describe methods to combine sensitivity analysis and optimization to address several possible quality issues persistent under and over estimation, specific bias, and random data failures. We will look at techniques to systematically investigate the effects of bias in reserve, probability, and cost estimation on the decision being considered. Finally, we will describe methods to choose portfolios that honor submitted data while reducing the impact of suspected bias and quality issues. .
Prediction of Wellbore Position Accuracy When Surveyed With Gyroscopic Tools
Authors: Torkildsen Torgeir , Håvardstein Stein T. , Weston John L. , Ekseth Roger 
Published: December 2007

Abstract
This paper describes a new method for estimation of well bore position accuracies, when using gyroscopic tools. The developed method represents a solution to the industry's need for a general and flexible error model which is applicable for all gyroscopic surveying tools and services.
The general gyro error model consists of a new set of error terms and a mathematical description of how the different error sources contribute to position uncertainties dependent on sensor configurations and operational modes. The model is suitable for appropriate modelling of most gyro surveying services.
The error propagation mechanisms are chosen to be identical to those in the ISCWSA’s MWD error model (SPE 67616), which has become an industry standard during the last five years. Thus future standardisation and software implementation are simplified. The description of the model and the attached numerical examples should be sufficient to implement the model.
The paper is a product of a collaborative work in ISCWSA (Industry Steering Committee on Wellbore Surveying Accuracy).
Upscaling Multiphase Flow Simulations in Heterogeneous Stratified Reservoirs by Optimal Layering
Authors: Artus Vincent , Nœtinger Benoit 
Published: December 2007

Abstract
Using some recent theoretical findings, we define an optimal vertical partition of stratified reservoir. This approach consists in merging several neighbor geological layers to define hydrodynamic layers. These hydrodynamic layers correspond to zones where the water oil front propagates without being deformed, even if these layers can be composed at smaller scale of several geological layers having different permeability values. This phenomenon is due to viscous crossflow effects that can stabilize the front. In a next step, a coarse vertical grid can be defined in accordance with this layering, optimizing the quality of coarse simulations.
We developed a simple numerical tool allowing a fast determination of different hydrodynamic layers as a function of the input permeability distribution and fluid mobility properties. Possible extensions to isotropic structures are also investigated.
History Matching and Quantitative Use of 4D Seismic Data for an Improved Reservoir Characterization
Authors: Mezghani M. , Fornel A. , Langlais V. , Lucet N. 
Published: December 2007

Abstract
In reservoir characterization, the value of each piece of data does not lie in its isolated use, but rather in the value it adds to the analysis when integrated with other data. Earth scientists from different disciplines have made many efforts to better predict the spatial distribution of petrophysical properties. However, the interpretation of isolated piece of knowledge, without a real integration of disciplines, cannot lead to a quantitative answer in terms of reservoir characterization. In this paper we present a joint inversion scheme for estimating petrophysical properties by integrating both production and 4D seismic related data in geological modeling. Simultaneous history matching of production and 4D seismic related data leads to a better prediction of petrophysical reservoir properties and of production forecast.