bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Mixed Finite-Element-Based Compositional Reservoir Simulator
Authors: Durlofsky L. J. , Chien M. C. H. 
Published: December 2007

Abstract
Geometrically complex geological features, such as faults, cross stratified beds and large scale inclined strata, can have very significant effects on the flow of reservoir fluids. Standard finite difference methodology lacks the geometric flexibility required for modeling flow through or around such structures. Triangle based discretization methods, by contrast, offer an attractive means to discretize and simulate flow through geometrically complex features accurately.
In this paper, a triangle based mixed finite element – finite volume technique for compositional reservoir simulation is developed. The formulation is of IMPES type and is applicable to three phase, multicomponent systems in two dimensions. Most previous mixed finite element formulations were restricted to two phase or fully miscible systems. The compositional approach presented here extends these earlier techniques though it retains the general structure of the more limited formulations. Specifically, the governing equations are cast in terms of a pressure equation and a series of component mass balance equations expressed in terms of the ‘total’ velocity. A triangle based mixed finite element method is applied to the solution of the pressure equation while a finite volume technique is employed for solution of the component mass balance equations. The overall methodology is particularly well suited for the modeling of flow through complex geological strata characterized by heterogeneous, generally anisotropic permeability fields. This is demonstrated explicitly through application of a preliminary implementation of the method to the simulation of flow through a faulted cross section with a complex permeability description. Extension of the formulation to the three dimensional case is also discussed.
The Simulation of Enhanced Oil Recovery Processes Using a Vapor/Liquid Equilibrium Model Based on Critical Scaling Theory
Authors: Sams W. N. , Lynch J. J. , Smith D. H. 
Published: December 2007

Abstract
Vapor-liquid equilibrium (VLB) calculations play an important role in the simulation of enhanced oil recovery (EOR) processes. While reservoir simulators in general must treat the VLE of hydrocarbon mixtures over a wide range of pressures and compositions, the simulation of such EOR processes as vaporizing and condensing gas drives require the VLE algorithm to operate at or near the critical point. Conventional VLE calculations based on cubic equations of state such as the Peng-Robinson or Soave-Redlich-Kwong equation fail to converge or are inaccurate in the critical region. In particular, it is well known that these methods assign the same value.to the critical z-factor for all pure chemical species.
The modified Leung-Griffiths model is a non-cubic, corresponding states theory that conforms to modern scaling laws, which successfully correlates, evaluates, and predicts VLE boundaries for fluid mixtures. The model performs well from the critical locus down to about half of the critical pressure. It has produced excellent correlations of many sets of binary hydrocarbon VLE data. We discuss the recent extension of the model to mixtures with three or more components and its application in a general purpose conpositional simulator. This paper examines how a flash computation is performed with this model, how the singlephase region is detected, and how the derivatives required in the solution of the non-linear flow equations are obtained from the flash computation. The model is coded in a form that makes it interchangeable with conventional VLE models in a wide variety of general purpose compositional simulators.
Cleaning Up Spilled Gasoline With Steam: Compositional Simulations
Authors: Adenekan A. E. , Patzek T. W. 
Published: December 2007

Abstract
A finite-difference compositional simulator has been developed and tested at U.C. Berkeley to model the flow of mixtures of Nonaqueous Phase Liquids (NAPLs) through the air zone and into aquifers. The simulator has been successfully used to history-match a steam injection pilot at a ‘Clean Site’ near the Lawrence Livermore National Laboratory in California -- a test site for the Gasoline Spill Area (GSA) cleanup pilot plannned for early ’93. Because of its multicomponent capabilities, the simulator has been used to calculate (a) production rates of individual gasoline components in the GSA to size treatment facilities, (b) areal and vertical distribution of gasoline after the first cycle of steam injection, and (c) steam injection rate that limits growth of the steam zone beyond the cleanup area. It has been shown that gasoline present in the penneable sands and gravel layers can be successfully recovered by injecting steam into these layers in a 7-spot pattern. For the conditions assumed in the model, it will take less than 16 days to recover nearly all of the gasoline hi the sands and gravel layers. By that time, the maximum aqueous concentrations of all hydrocarbon components in these layers will have dropped to less than 0.01 mg/1. The results show that vaporization, followed by bulk movement of the vapor to the production well is the dominant recovery mechanism. In tenns of time required for cleanup, model results are most sensitive to penneability of the medium. Other parameters, such as the relative penneabilities and the number of components, also affect the outcome, but to a lesser extent.
Vectorization and Parallel Processing of Local Grid Refinement and Adaptive Implicit Schemes in a General Purpose Reservoir Simulator
Authors: Chien M. C. H. , Northrup E. J. 
Published: December 2007

Abstract
With less computer memory usage and a fewer number of calculations, local grid refinement and adaptive implicit schemes can effectively achieve similar accuracy as fully refined, fully implicit schemes. However, these methods become less appealing on a vector processor because they are not as susceptible to vectorization as the latter. This paper discusses the development of a vectorized, parallel-processed algorithm for the local grid refinement and adaptive implicit schemes in a general purpose reservoir simulator. The adaptive implicit scheme is considered as a subset of the dynamic, multilevel, mixed implicit, local grid refinement models.
The algorithm was tested on an enlarged 12th SPE comparative solution problem. Results indicate a fivefold speed improvement due to vectorization. Compared to a fully implicit, fully refined model, the local grid model requires 63% less computer memory and 42% less computer time without notable loss of accuracy.
Time-Dependent Incorporation of Locally Irregular Grids in Large Reservoir Simulation Models
Authors: Deimbacher F. X. , Heinemann Z. E. 
Published: December 2007

ABSTRACT
In field-scale reservoir simulation the demands to the grid-in-use may change significantly during a simulation run. Introduction of new wells (vertical and horizontal ones) at a later stage of the simulation run, phase breakthrough or coning may require a different grid than initially set up.
While in the past the reservoir simulation grid was considered static, this paper will describe a novel approach of a dynamically used grid. It is only applied locally and just for a specific time period. The geometry within such a local subdomain (window) may be regular or irregular and the grid construction is based upon the principle of perpendicular bisectors (PEBI or VORONOI grid).
Windows may be incorporated into the standard Cartesian simulation grid at any time and at any location. No non-neighborhood connections are used. The windows are linked to the system of equations based on their natural sequence and they are "switched on and off" as required. A multiple timestepping technique is applied that allows the use of different timestep lengths inside and outside the windows.
Examples will demonstrate the potential of this new concept. A local radial grid may be used for well test simulation, or arbitrary direction horizontal wells may be incorporated after history matching. The whole simulation is conducted using the familiar Cartesian grid with the irregular grids included only during a short period.
Dynamically Adaptive Godunov Schemes with Renormalization in Reservoir Simulation
Authors: Edwards Michael , Christie M. A. 
Published: December 2007

Abstract
Simulation of unstable flow pr.cesses requires the use of both accurate and efficient techniques. Accurate results have been obtained efficiently for flow in a uniform permeability field, by using a higher order Godunov scheme combined with dynamic grid adaptivity. Application of the adaptiye higher order scheme to unstable flows resuiting from a randomly varying permeability field is described here. Use of dynamic grids with varying levels of refinement demands an adaptive definition of the permeability field. Effective permeabilities of coarsened grid blocks are defined by local cell renormalization. High resolution results are obtained together with large savings in computer time.
A Finite-Element Black Oil Simulation System for Heterogeneous Reservoirs with Horizontal Wells Having Vertical Hydraulic Fractures
Authors: Kocberber Sait 
Published: December 2007

Abstract
In this study, a newly developed threedimensional, fully implicit, finite element black oil simulation system for heterogeneous reservoirs with horizontal wells and vertical fractures is presented. This simulation system utilizes an efficient and almost fully automatic three-dimensional finite element grid generation technique with natural grid refinement capabdities around wells and fractures. The region between the well/fracture system and the outer boundary is gridded by an automatic tettahedronization scheme such that selective refinement and accurate representation of heterogeneities are achieved. The result is a fine and well graded grid based on expected flow patters around the well/fiacture system.
In this simulation system the wellbore is tteated as a hollow tube. The multi-phase black oil flow within fractures is accurately modeled including variable fracture conductivity. Furthermore fracture and reservoir flow equations are analyticaly coupled utilizing continuity of fluxes at the domain interfaces. This allows easy application of established black oil simulation techniques to reservoirs with horizontal wells and vertical fractures.
The use of the model is demonstrated in simulating waterflooding in a square reservoir using one horizontal injection well and two vertical production wells. The model seems to produce accurate numerical results almost free of grid orientation effects.
The Fractal Nature of Viscous Fingering: Saturation Profiles and Fractional Flows From Modeling of Miscible, Two-Component Flows in Two-Dimensional Pore Level Models
Authors: Ferer M. V. , Sams W. N. , Geisbrecht R. A , Smith D. H. 
Published: December 2007

Abstract
Use of saturation-dependent relative mobilities leads to linear flow in wliich the saturations scale as x/t (i.e., position/time). However, experiment and theory liave shown ttiat, in the limit of very large viscosity-ratio, the flow is not linear but fractal. Thus, two questions naturally arise: i) If the actual viscous fingering were fractal, what would be the effect on traditional reservoir simulation? and ii) Is the viscous fingering fratfal for viscosity-ratios of real reservoirs?
To study the first question, we used general arguments to show that fractal flow produces saturations which scale not as x/t but rather as x/t1+ε and fractional flow curves which are functions not solely of saturation S but rather t ε S Thus, when the flow is fractal, fractional flows and the relative mobilities depend on time t and saturation s not solely on saturation. Earlier studies have determined the values of ε : in three dimensions, ε ≈ 1 : in two dimensions, ε ≈ 0.4. Using a standard pore-level model of twodimensional, miscible floods, we have shown that the flow for this model is fractal for a large viscosity-ratio (M=10,000) and that the functional dependencies of the saturation and fractional flow agree with the results of our general arguments but not with the results from the traditional models, such as Buckley-leverett or Koval.
We addressed the second question using our model, witfi viscosity-ratios, M = 3 → 300. Our modeling of, the finite viscosity-ratio showed that, initially, the flows are fractal; but that they become compact or stable on a time scale, τ, which increases with viscosity-ratio.as τ =τOM0.17. Once stable, the saturation front advances as x = VOM0.068 t.
Furthermore, using our functional dependency of fractional flow, we showed that the factor M0.068 plays the role of a two-dimensional Koval factor.
Adaptive Implicit Volume Balance Techniques
Authors: Farkas Èva 
Published: December 2007

Abstract
Implicit improvement possibilities of the VB modeling technique are studied in this paper. Short overviews deal with the different variable sets of reservoir simulators, and the IMPEM(E) VB solution. Then, the felly implicit approxhnation is discussed. The IMPEM and implicit parts of this technique are separated and analyzed. Two adaptive implicit VB methods, are examined. Some comparisons of the calculations are demonstrated using a ID radial model.
Development of Dynamic Local Grid Refinement in Reservoir Simulation
Authors: Ding Yu , Lemonnier P. A. 
Published: December 2007

Abstract
In reservoir simulation, the grid size is usually too large, to give accurate results, especially in active regions near wells and displacement fronts. A grid refinement of the whole domain is very memory and CPU time consuming for field-scale simulations. Dynamic local grid refinement can be used to overcome this problem.
In this paper, an adaptive local grid refinement method is presented for two-phase threedimensional immiscible flow. Data structure and grid management are proposed which are very efficient for dynamic grid monitoring. Several levels of refinement are allowed, space discretization is based on the finite-volume method. The linear system is solved by an ILU-ORTHOMIN method well-suited for irregular gridding. The criteria for refinement and unrefinement are based both on the saturation threshold and the flux tolerance.
Some examples are given to show the ability of the adaptive method to track the displacement fronts in heterogeneous reservoir simulations. The quality and accuracy of the solution are similar to those obtained with a fine discretization over the whole domain while great savings of grid blocks and computer time are obtained.
Reservoir Engineering Aspects of Horizontal Drilling in an "Ultra-Thin" Oil Column: A Case Study
Authors: Curnutt R. C. , Benesch J. M. , Prikel K. M. , Indrarto Dradjat , Sumolang F. G. H. 
Published: December 2007

SUMMARY
This paper focuses on P.T. Stanvac Indonesia's (PTSI) efforts to evaluate, justify and drill a horizontal well at the current edge of Industry technology. This pilot well, Gunung Kembang 7 (GK-7), located in a remote area of South Sumatra, Indonesia, was drilled successfully within an "ultra-thin" 33-foot oil column encompassed by both a gas cap and aquifer (see simplified cross section, Figure 1). Vertical wells in this field produce at low oil rates and yield marginal to non-commercial economic results.
The paper details efforts to numerically model the optimum case for vertical and horizontal wells to allow a fair economic comparison. Each alternative's optimum was derived by determining the respective spacing and rate for maximum profitability. Other associated studies are also discussed in addition to well performance and the actual horizontal drilling and completion results.
Reservoir Limit Testing in Water-Drive Systems
Authors: Kaczorowski N. J. 
Published: December 2007

Abstract
Reservoir limit testing is a powerful tool to determine the reservoir volume of a bounded system. This procedure was first recognized by Jones1 Its use, however, has been restricted to depletion drive systems due to the boundary conditions assumed to solve the radial pseudo steady state flow diffusivity equation.
There are many instances when determining the remaining hydrocarbon volume is desired after production has commenced. In a bounded system, Jones' method is applicable. But in water drive systems, water influx affects test results and Jones' method is not applicable.
An empirical method has been developed to accurately determine the moveable hydrocarbon volume in water drive systems. This new technique provides a means to determine not only the moveable hydrocarbon volume but also aids in the determination of accurate values of permeability and skin. It has been verified with numerical reservoir simulations and applied to actual field data.
This method is particularly applicable to determine remaining moveable hydrocarbon volumes in water driven gas reservoirs of small to moderate size and oil reservoirs above the bubble point. Because this method requires reaching pss flow at two different rates, it may prove impractical in large, low pressure gas reservoirs or those with many wells.
Simulation of Rapid Depressurization and Blowdown of an Offshore Oil Pipeline
Authors: Zagalai B. M. , Montgomery D. W. , Redus C. L. , Tan T. K. 
Published: December 2007

Abstract
A practical investigation is reported of rapid depressurization and blowdown in case of riser rupture of an offshore pipeline exporting live oil at high pressure. This work was performed to assess the environmental and safety consequences of not installing sub-sea isolation valves on the Heather-Ninian pipeline. The Heather Field is close to its economic limit, consequently, the overriding objective was to evaluate changes in operating procedure which would provide an equivalent level of safety to that of installing a sub-sea isolation valve.
Three methods – simple analytical, approximate and rigorous numerical simulation were used to predict leak rates in case of riser rupture. To build confidence in the predictions, a blowdown test to the separators on the exporting platform was performed. The test results are in good agreement with the model predictions.
The oil was found to have a bubble point pressure near the threshold pressure at which riser rupture could cause sustained hydrocarbon release due to solution gas drive in the sub-sea pipeline. As a result, the process facility on the exporting platform was modified to lower the bubble point pressure. The effects are compared to the installation of a sub-sea isolation valve. A blowdown system on Heather platform was shown to be effective when the leak is from a hole with a diameter of less than 2 inch (50 mm).
Monel Cladding as Splash Zone Coating for Pipeline Risers
Authors: Vastenholt H. , Fukuda T. 
Published: December 2007

Abstract
It has been identified that neoprene coated risers of large gas pipelines, expose continually manned platforms to high safety risks. The neoprene is susceptible to impact damage and due to peeling, corrosion may occur along the edges of the coating. Available alternatives to reduce those risks are for instance: to terminate those gas pipelines at a separate riser platform, or to install riser fenders in combination with improvements to the riser splash zone coating. Monel has been used in some instances in the oil industry as an alternative to neoprene as riser coating. In these cases the Monel was applied as sheeting; however inspection of the riser by ultra-sonic means was not possible because of the gap between the Monel sheets and riser pipe.
This paper addresses the possibility of continually bonding the Monel onto the riser pipe by means of hot rolling, thereby maintaining the ability to inspect the risers with ultra-sonic means. However this production process has some areas of concern: in particular, iron contamination of the Monel reduces its corrosion resistance in sea water. This paper reports on the trials that were conducted to quantify the above problem associated with iron contamination and a solution is provided.
Gas-Lift Optimisation on Barrow Island, Western Australia
Authors: Mantecon J. C. 
Published: December 2007

Abstract
Improving the design and Operation of gas lift Systems to obtain Optimum production (within the limits of existing facilities) is very attractive with low Investment and a corresponding acceleration/increase in reserve recovery to maximise profit.
This paper discusses the studies conducted and methods used to increase oil production and optimise the gas injected/fluid produced ratio in the Barrow Island Field by utilising the existing compression capacity and field staff.
This multi-stage optimisation program used on Barrow Island (BWI) can be readily adapted to other producing areas, even those with limited remaining field life. During the first stage, emphasis was placed on: (1) individual well optimisation; (2) improving gas lift design techniques; (3) Converting to intermittent gas lift (IGL), gas assisted plunger lift (PL) or sucker rod pumping when continuous gas lift (CGL) was no longer efficient; (4) improving System diagnostics; (5) field personnel training, and; (6) enhancing Operations / Engineering communication. After the first stage is completely implemented and results evaluated, fieldwide optimisation is planned and will be actively pursued.
Performance results indicate a very attractive retum from a low risk Investment. Significant improvements have been obtained in: (1) individual well profitability; (2) optimising injection gas usage; (3) well monitoring, and; (4) the amount and quality of collected well data.
Additional intangible benefits have come from the much closer well surveillance, such as faster detection and diagnosis of problems, and quicker response to failures.
The results demonstrate the potential that exists in producing areas similar to BWI for maximising economic retum through the application of sound engineering and operating principles. A united effort from Operating and Engineering personnel that is strongly supported by Management, along with an effective communication and training program can improve gas lift System efficiency quicker and more consistently to minimise costly errors and/or delays.
Emulsion Treatment Program
Authors: Soffian Roslan M. , Niven T. L. 
Published: December 2007

Abstract
Increasing emphasis has been placed by Esso Production Malaysia Inc. (EPMI) to address the potential emulsion concems in its existing operations in light of projected increases in water production offshore and in anticipation of potential impact on its export crude quality. The proper approach to demulsification is offen a point of contention, as a generic solution to oil treatment is relatively difficult to find. Although oil treating approaches can be grouped into four main categories, i.e., heat, Chemical, settling time, and agitation, each producing System is unique and must be reviewed individually to arrive at its respective solution.
This paper will discuss EPMI efforts to identify methods of resolving its emulsion concems, with focus on one of its offshore locations, Guntong Complex. This paper will discuss the initial provisions included in the original platform design basis, tests performed to identify resolution requirements and studies to determine the Optimum practical facility requirements.
This paper will focus on EPMI's efforts to remove water from emulsified crudes (forward emulsion treatment) only. Produced water treatment disposal is not addressed in this paper.