bluuebunny/crossref_metadata_2025_split huggingface dataset:
Streamline Tracing on Curvilinear Structured and Unstructured Grids
Authors: Prévost Mathieu , Edwards Michael G. , Blunt Martin J. 
Published: December 2007

Abstract
The streamline method has proved to be extremely successful for reservoir simulation1. For a Cartesian grid the standard five point (7 in 3-D) discrete pressure equation is employed within the IMPES streamline method. The accuracy of the velocity field plays a critical role in the success of the technique, which relies on precise determination of streamline paths.
Modeling complex geology and geometry requires the use of sophisticated grids and thus the ultimate power of the streamline method will only be realized when the method is extended to general curvilinear grids.
In this paper a generalization of the Cartesian tracing algorithm is developed for general tensor fields on structured (corner point) grids and unstructured grids. The extension of the method requires the identification of appropriate volumes and fluxes over which tracing equivalent to the Pollock Cartesian method2 can be performed. Essential components of the method include the use of flux-continuous finite-volume schemes for the different grid types coupled with a novel flux recovery technique and a generalization of streamline tracing to polygons.
A New Streamline Method for Evaluating Uncertainty in Small-Scale, Two-Phase Flow Properties
Authors: Hastings J. J. , Muggeridge A. H. , Blunt M. J. 
Published: December 2007

Abstract
Variations of permeability and relative permeability due to small-scale heterogeneities, such as cross-bedding, can have a significant impact on reservoir performance1,2. These properties (particularly relative permeability) are typically very poorly quantified, and yet they represent an important uncertainty in predictions of oil recovery. However, it is currently impossible to model even a single realisation of these small-scale features with a field-scale finite difference simulator.
This paper presents a new, semi-analytical streamline method that allows rapid quantification of this uncertainty. The properties along each streamline are upscaled analytically to provide effective permeability, porosity, relative permeability and geometry for that streamline. This is achieved by a new method for upscaling total mobility in 1dimension, which, combined with an existing method for fractional flow3, enables us to reproduce production and watercut behaviour versus time for specified rate or pressure well conditions. Production curves from the streamlines are combined numerically to give field-wide values.
A stochastic model of a cross-section through a fluvial reservoir is used to demonstrate that the new method requires only a single pressure solution to calculate the distribution of oil recovery caused by small-scale variations in absolute and relative permeability.
Rapid History Matching Using a Generalized Travel Time Inversion Method
Authors: Wu Zhan , Datta-Gupta Akhil 
Published: December 2007

Abstract
We propose a generalized travel time inversion method for production data integration into reservoir models using finite-difference reservoir simulators. Our approach is motivated by seismic waveform imaging and is particularly well-suited for large-scale field applications because the computation cost depends only on the number of wells regardless of the number of parameters or the amount of observed data. Instead of matching the production data directly, we minimize a 'travel time shift‘ at each well derived by maximizing the cross-correlation between the observed and calculated production response. An optimal control method is used to compute the sensitivity of the travel time with respect to reservoir parameters. Finally, data integration is carried out via a modified Gauss-Newton method.
There are several advantages associated with the proposed travel time inversion method. First, it is robust and computationally efficient. The travel time misfit function is quasilinear with respect to changes in reservoir properties. As a result, the minimization is relatively insensitive to the choice of the prior model. Second, the computational cost associated with the sensitivity computation depends only on the number of wells which can be orders of magnitude lower than the number of parameters or the amount of observed data. This offers tremendous advantage over the commonly used gradient simulator method or the conventional adjoint methods that attempt to minimize the production data directly. Furthermore, the travel time approach also offers computational advantage during minimization of the misfit function using the Gauss-Newton algorithm. We have presented several examples to demonstrate the power, generality and practical feasibility of our proposed approach for large-scale field applications.
Combining Global and Local Optimization Techniques for Automatic History Matching Production and Seismic Data
Authors: Mantica S. , Cominelli A. , Mantica G. 
Published: December 2007

Abstract
Gradient based optimization techniques in computer-aided history matching are increasingly adopted by oil industries, because of the great time saving they can offer over conventional trial and error approaches. However, these methods lead to the identification of a single set of parameters, thus neglecting the inherent non-uniqueness of the solution of the underlying inverse problem. In this paper we propose a new approach that couple a chaotic sampling of parameter space with a local minimization technique. The first step is effected evolving a non-linear dynamical system, by which we identify several points to be successively used as initial guesses for a local, gradient based, optimizer. This provides a series of alternative matched models, with different production forecasts, that improve the understanding of the possible reservoir behaviors. The validity of this approach has been proven on a synthetic reservoir derived from a real West Africa field.
MPFA for Faults and Local Refinements in 3D Quadrilateral Grids With Application to Field Simulations
Authors: Aavatsmark I. , Reiso E. , Reme H. , Teigland R. 
Published: December 2007

Abstract
This paper extends the multipoint flux-approximation (MPFA) control-volume method to 3D quadrilateral grids for which the adjacent cells do not necessarily share corners. Examples are grids with faults and locally refined grids. This paper gives a derivation of the method for such grids.
The difference between two-point flux-approximation (TPFA) results and MPFA results for faults is demonstrated for synthetic problems. Further, the results are compared with results from uniform fine-grid simulations. The effect of repeated fault patterns as well as anisotropy is investigated. Large errors may be found for the TPFA method for flow through a series of faults in an anisotropic medium. Finally, a comparison is done for a reservoir field application.
Split Full Tensor Discretization Operators for Structured and Unstructured Grids in Three Dimensions
Authors: Edwards Michael G. 
Published: December 2007

Abstract
A full tensor velocity field occurs in reservoir simulation whenever the computational grid is non-aligned with the tensor principal axes. Three contributing factors that can give rise to a full tensor pressure equation in reservoir simulation are anisotropic media, upscaling (with cross-flow effects) and non K-orthogonal structured and unstructured grids.
The introduction of a full tensor typically increases the support of the standard scheme on a logically rectangular grid from 7 to 27 nodes in 3-D, which can increase simulation costs by over 100% in 3-D.
A major assumption in many simulators is that the pressure equation always has a diagonal tensor. The design and efficiency of such codes is intrinsically linked to the diagonal tensor assumption. However, when employing general non K-orthogonal grids with corner point geometry the diagonal tensor assumption leads to an O(1) error in velocity field.
The focus of this paper is on the development of finite volume schemes that maintain consistent full tensor flux approximations while retaining standard diagonal tensor Jacobian matrix inversion in three dimensions on structured and unstructured grids. Three dimensional Hexahedral and Tetrahedral grid examples are included which demonstrate the benefits of the method.
New Numerical Schemes for the Near-Well Modelling with Discretization Around the Wellbore Boundary Using Flexible Grids
Authors: Ding Y. , Jeannin L. 
Published: December 2007

Abstract
The control-volume schemes are discussed for the modelling of vertical wells using flexible grid.
The main difficulties of the well modelling in the reservoir simulation is the problem of the scale between the reservoir size (several kilometers) and the wellbore radius (several centimeters). In applications, although the wellbore boundary can be discretized using the flexible grid, the gridblocks in the well vicinity are usually not small enough compared to the wellbore radius, and the gridblock sizes vary usually geometrically in the radial direction from the well. This kind of grid makes the standard linear approach inefficient for the near-well flow modelling.
In this paper, new numerical schemes, which are based on logarithmic approach, are proposed to improve the standard linear approach for the near-well modelling. In particular, a multi-point and a two-point flux approximation scheme are presented. These schemes can reduce the calculation errors for the dominating "singular" well flow. Consequently, good results are obtained with these new schemes. The proposed approach can be used for any kind of flexible grid for the near-well modelling.
A Methodology for Simulation of Vuggy and Fractured Reservoirs
Authors: Kossack C. A. , Gurpinar O. 
Published: December 2007

Abstract
The proper treatment of oil recovery from vugs is an important part of evaluating a triple porosity reservoir. This paper evaluates the rate of oil recovery from isolated vugs, that is vugs that are not connected to the fracture system. Simulations of triple porosity systems are made with fine grid, single porosity and dual porosity and dual porosity models.
The effect of the ratio of viscous forces to gravity forces on oil recovery from vugs is evaluated for a wide rate of ratio of the forces.
A procedure is presented for creating composite curves (Pcow and krow) to be used in a dual porosity simulator to emulate oil recovery from triple porosity systems. This technique is designed for situations where no experimental displacement results are available. Discussions show that these composite curves are more reliable that the results from matching experimental displacements.
Two examples of this process are shown: one at a low and another at a high value of the viscous to gravity ratio. Two realizations are matched to demonstrate how one would create average composite curves in a field situation.
On Near Wellbore Modeling and Real Time Reservoir Management
Authors: Bøe Ø , Flynn J. , Reiso E. 
Published: December 2007

Abstract
This paper is concerned with the problems of real time reservoir management, simulation while drilling and near well bore modeling. These problems are discussed in terms of work process, feasibility as well as numerical and simulation related aspects. A software tool developed to perform high precision local simulation and at the same time account for global field behaviour is described. Field examples are presented to illustrate the potential and use for simulation while drilling exercises.
Numerical Subgrid Upscaling for Waterflood Simulations
Authors: Arbogast Todd , Bryant Steven L. 
Published: December 2007

Abstract
We present a subgrid-scale numerical technique for upscaling waterflood simulations. We scale up the usual parameters porosity and relative and absolute permeabilities, and also the location of wells and capillary pressure curves. Some of these are critical nonlinear terms that need to be resolved on the fine scale, or serious errors will result. Upscaling is achieved by explicitly decomposing the differential system into a coarse-grid-scale operator coupled to a subgrid-scale operator. The subgrid-scale operator is approximated as an operator localized in space to a coarse-grid element. An influence function (numerical Greens function) technique allows us to solve these subgrid-scale problems independently of the coarse-grid approximation. The coarse-grid problem is modified to take into account the subgrid-scale solution and solved as a large linear system of equations. Finally, the coarse scale solution is corrected on the subgrid-scale, providing a fine-grid scale representation of the solution. In this approach, no explicit macroscopic coefficients nor pseudo-functions result. The method is easily seen to be optimally convergent in the case of a single linear parabolic equation. The method is several times faster than solving the fine-scale problem directly, generally more robust, and yet achieves good results as it requires no ad hoc assumptions at the coarse scale and retains all the physics of the original multiphase flow equations.
Full-Physics, Streamline-Based Method for History Matching Performance Data of a North Sea Field
Authors: Agarwal Bijan , Blunt Martin J. 
Published: December 2007

Abstract
Streamline-based methods for history matching are appealing for two reasons. First, the forward simulation is potentially much faster than conventional simulation methods for displacement-type problems. Second, time-of-flight information along the streamlines can be used to find sensitivity coefficients in an efficient and elegant manner. However, current streamline history matching methods use forward simulations that ignore the effects of gravity and compressible flow. These effects may be critical in analyzing early-time performance data. If relevant physical effects are neglected in the forward simulation, the history matched reservoir description may not be consistent with the actual field, and predictions from the model will not be reliable.
We present a method for history matching watercut data using a streamline simulation that captures all the pertinent physics, including compressible three-phase flow with gravity. We use a methodology based on the assumption of one-dimensional flow along streamlines to find the sensitivity of water flow rate at production wells to changes in permeability. Although the computation of the sensitivities is approximate, the method provides a good history match for problems with significant effects due to compressibility and gravity.
Data from a North Sea field is used to test the technique. Using a full-physics streamline model gives a reasonable history match and a good prediction of future performance.
Scale Splitting Approach to Reservoir Characterization
Authors: Grimstad A. A. , Mannseth T. , Nævdal G. , Urkedal H. 
Published: December 2007

Abstract
Production forecasts are essential for sound reservoir management. The foundation for such forecasts is a characterization of relevant reservoir properties. These properties are usually determined through history matching, using production data, static well data (hard data), and the up-scaled geological model (prior model), simultaneously. This process if often very complex and costly, both in terms of CPU-time and man-hours.
To reduce cost and complexity of reservoir characterization, we propose an alternative methodology; scale splitting. This approach utilizes the fact that production data often contain information about variability of reservoir properties on a much coarser length scale than the other data do. Hence, production data alone can be used to determine the large-scale variation in the estimated properties. The selection of parameters that can be estimated from the production data are determined through a data driven, top-down search, starting with a single parameter representing the average property for the reservoir structure in question. One of the primary objectives of this search is to keep the number of parameters as low as possible, without sacrificing the match quality.
The prior model and the hard data need to be integrated to allow also for finer-scale property variation, and to match hard data at well locations. With scale splitting this is done at low cost after the history match of production data.
We present the scale splitting approach for absolute permeability estimation and give examples where it is compared to other approaches in terms of match quality and work load.
Uncertainty Analysis in Reservoir Production Forecasts During Appraisal and Pilot Production Phases
Authors: Steagall D. E. , Schiozer D. J. 
Published: December 2007

Abstract
The objective of this paper is to present a methodology for quantification of the impact of uncertainties in the economic evaluation of reservoirs. The methodology is based on the numerical flow simulation of many representative models of possible scenarios of the reservoir, through the combination of the attributes with uncertainty that characterize the reservoir. A set of data representing uncertainty values for each select attribute, and its associated probabilities are combined by the decision tree technique. After the simulation, a statistic treatment is done to obtain the expectation curve of production forecast and net present value. The procedure is done in a network of workstations, using parallel computing, with great reduction in the processing time and ensures the practical usage of this methodology. The methodology is applied to a real offshore field in Campos Basin – Brazil, in the appraisal phase, with few wells and few seismic lines.
An Integrated Partially Implicit Compositional Simulator for Naturally Fractured Reservoirs
Authors: Jigen Ye , Pingping Shen , Mingxin Liu , Chunqiu Guo 
Published: December 2007

Abstract
This paper describes an efficient method for solving the equations corresponding to an equation-of-state compositional model. The method is developed for a partially implicit compositional simulator in which the thermodynamic equilibrium equations and flow difference equations are solved separately and sequentially. The reduced system of linear equations consists of three equations with three unknowns per grid. So the equation number to be solved simultaneously is much less than that of the fully implicit method. Only pressure, oil saturation and gas saturation are solved implicitly in this partially implicit method while the total mole fraction of components is computed explicitly. If the increment of pressure as well as water saturation, gas saturation or total mole fraction of components of some grids is greater than a small given value, a implicit method can be applied easily to one individual grid to modify the calculation results.
An efficient integrated compositional simulator is obtained by combination of the simulator mentioned above with reservoir description model. The simulator can generate grid description input data and reservoir property input data conveniently according to the results of geological analysis, core analysis, well testing and log information. It can also help us view the simulation results and modify the geological model easily if necessary.
The partially implicit compositional simulator has been tested with several practical gas condensate reservoirs. Its simulation results are reasonably similar to those computed by fully implicit approach.
Chemical Treatment of Cuttings Drilled With Oil-Based Mud Employing a Laboratory Simulated Soil Washing Procedure
Authors: Perry M. L. , Griffin J. M. 
Published: December 2007

Abstract
With the emphasis being placed on environmental safety in recent years, companies are seeking economical methods for cleaning oil field waste. Drilling operations produce substantial amounts of such waste in the form of cuttings and used drilling mud. Oil-based or synthetic based muds, which are necessary in some drilling situations, increase the difficulty of cleanup operations due the increased hazards these fluids pose to the environment. One chemical washing agent has been identified that demonstrates potential for successfully reducing the TPH content of oil-based mud cuttings to below the required level.
Communication As A Tool Of Management
Authors: Oncken William 
Published: December 2007

Introduction
Communication as a tool of management (administration communication) is that interchange of fact, viewpoints, and ideas which brings about unity of interest clarity of purpose, and integration of effort in a group of individuals organized to achieve a specific mission.

II. THE IMPORTANCE OF COMMUNICATION TO ORGANIZED EFFORT
A. Communication is an integral part of the management process to obtain production and efficiency.
Planning
Organization
Directing
Coordinating
Controlling
Communication is an integral part of the motivating process. People work to satisfy the following needs:
The need for opportunity
The need for recognition
The need for belonging
The need for security
Blocks to effective communication
The individual uses the language of personal motivation.
Management uses the language of production and efficiency.
A Mechanistic Model to Predict Natural Gas Separation Efficiency in Inclined Pumping Wells
Authors: Harun A. F. , Prado M. G. , Serrano J. C. , Doty D. R. 
Published: December 2007

Abstract
A new mechanistic model to predict the natural separation efficiency in deviated pumped wells has been developed based upon the combined phase momentum equations and a general slip closure relationship. The model incorporates two important parameters that are both functions of flow pattern; the local void fraction in front of the pump intake ports and the drag coefficient. The void fraction is, in turn, a function of the bubble rise velocity. The model uses existing void fraction and bubble rise velocity correlations developed by Hasan and Kabir1 for both bubbly and slug flow. The transition between bubbly and slug flow is determined by using the Hasan2 and Hasan and Kabir3 criteria. The Barnea et al.4 critical angle criterion below which bubbly flow cannot exist is also used by the model. A general drag coefficient correlation for slug flow has been developed based on data gathered by Serrano5 on a water-air system for inclination angles of 30 and 60 degrees.
Comparisons between the model's predictions and the experimental data of Serrano5 show excellent agreement. Sensitivity studies developed using the model indicates that the natural separation efficiency decreases as the liquid rate, inclination angle and gas-liquid ratio increase and as the annulus area decreases. For the wellbore configuration and operating conditions under investigation, the model predicts the existence of a minimum liquid rate below which the system reaches 100 percent gas separation efficiency.
Tip Screenout Designs and Alternative Height Growth Containment Techniques
Authors: Engels John N. , England Kevin W. 
Published: December 2007

Abstract
In March of 1999 a series of six hydraulic fracturing treatments were performed in an area of Algeria known as TFT (see Figure 1 ). Seven wells (6 producers and 1 injector) were to be fracture stimulated with risk of propagating into lower mobile water zone. A series of treatment design steps were carried out for each well that helped prevent excessive height growth while fracturing and ultimately limited water production after the treatments. The methodology incorporated utilizes both two-dimentional and pseudo three-dimentional fracture modeling in order to estimate different scenarios of fracture height growth. This method resulted in a better estimation of fluid volumes and pump rates that would limit height growth, yet optimize proppant placement and fracture conductivity in the productive part of the interval. The resulting net increase in oil production from the six producer wells was over 29.93 m3/hr. This paper explains the design methodology used during the campaign and presents representative case histories.