bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Sensitivity Study of the Effect of Parameters on Results From an In-Situ Combustion Simulator
Authors: Anis M. , Hwang M. K. , Odeh A. S. 
Published: December 2007

Abstract
A study of the sensitivity of results from an in-situ combustion simulator to key parameter variations was made. The model was based on the finite-difference method of solution and accounted for the kinetics of the combustion process. The parameters were block size, dimensionality of the model, number of reactions, activation energy, reaction constant, and injection rate.
About 50 dry-combustion simulation runs were made using the model in one-, two-, and three-dimensional (ID, 2D, and 3D) modes. The chemical properties for a heavy oil were used. In general, runs were carried out for 6,000 days. The output results were cumulative oil production, oxygen consumption, peak temperature, injection bottomhole pressure (BHP), WOR, GOR, heat release from reactions, fuel consumptions, and saturation distribution.
The results were most sensitive to the flow convection parameters, such as block size and dimensionality. Kinetic parameter effects were not as significant as previously thought. Moreover, the investigation identified practical difficulties in running a kinetic-based model. Numerical distortion of the convection effects with large grid blocks limits the utility of such models. A brief discussion of a possible method to overcome some of the difficulties is given.
A Two-Dimensional Theory of Fracture Propagation
Authors: Biot M. A. , Masse L. , Medlin W. L. 
Published: December 2007

Summary
A basic theory of two-dimensional (2D) fracture propagation has been developed with a Lagrangian formulation combined with a virtual work analysis. Fluid leakoff is included by the assumption that an incompressible filtrate produces a piston-like displacement of a compressible reservoir fluid with a moving boundary between the two. Poiseuille flow is assumed in the fracture. We consider both Newtonian and non-Newtonian fluids with and without wall building. For non-Newtonian fluids, we assume the usual power-law relation between shear stress and shear rate. The Lagrangian formulation yields a pair of nonlinear equations in Lf and bj, the fracture length and half-width. By introducing a virtual work analysis, we obtain a single equation that can be solved numerically. For non-wall-building fluids, it predicts much higher leakoff rates than existing methods. The Lagrangian method also allows nonelastic phenomena, such as plasticity, to be included. A practical computer program developed from this theory has been used for more than 10 years to design fracturing treatments in oil and gas reservoirs in Canada, California, the midcontinent and Rocky Mountain areas, the U.S. gulf coast, the North Sea, and in northern Germany. In most of these applications, it has predicted fracture dimensions that have been in line with production experience. Optimization methods based on this program led to very large fracturing treatments in low-permeability gas sands that were forerunners of massive fracturing treatments in tight gas sands. Specific examples in which this method was used to design fracturing programs in large gas fields in Kansas and Texas are discussed.
Nonisothermal Effects During Injection and Falloff Tests
Authors: Benson S. M. , Bodvarsson G. S. 
Published: December 2007

Summary
Numerically simulated pressure transients during injection and falloff tests are analyzed to develop methods for obtaining the correct permeability/thickness of the reservoir and the skin factor for the well. The results show that to analyze correctly the pressure transients governed by a moving thermal front, the fluid-property values must correspond to the temperature of the injected fluid. For pressure falloff tests and for injection tests conducted in a well cooled by previous injection or drilling, however, the physical properties of the in-situ reservoir fluids must be used. The application of conventional isothermal methods for calculating skin values from injection and falloff data will give erroneous results. A new method is presented for calculating skin values from injection and falloff data that accurately corrects for nonisothermal effects. Examples are given to illustrate this analysis method. The technique is applied to the analysis of injection test data from a well located in the East Mesa geothermal field in southern California.
Some Practical Issues on Real-Time Reservoir Model Updating Using Ensemble Kalman Filter
Authors: Wen Xian-Huan , Chen Wen H. 
Published: December 2007

Summary
The concept of "closed-loop" reservoir management is currently receiving considerable attention in the petroleum industry. A "realtime" or "continuous" reservoir model updating technique is a critical component for the feasible application of any closed-loop, model-based reservoir management process. This technique should be able to rapidly and continuously update reservoir models assimilating the up-to-date observations of production data so that the performance predictions and the associated uncertainty are up-to-date for optimization of future development/operations. The ensemble Kalman filter (EnKF) method has been shown to be quite efficient for this purpose in large-scale nonlinear systems.
Previous studies show that a relatively large ensemble size is required for EnKF to reliably assess the uncertainty, and a confirming step is recommended to ensure the consistency of the updated static and dynamic variables with the flow equations. In this paper, we further explore the capability of EnKF, focusing on some practical issues including the correction of the linear and Gaussian assumptions during filter updating with iteration, the reduction of ensemble size with a resampling scheme, and the impact of data assimilation time interval.
Results from the example in this paper demonstrate that the proposed iterative EnKF performs better with more accurate predictions and less uncertainty than the traditional noniterative EnKF. The use of iteration reduces the impact of nonlinearity and non-Gaussianity. Results also show that iteration may only be required when predictions are considerably deviated from the observations. The proposed resampling scheme can significantly reduce the ensemble size necessary for reliable assessment of uncertainty with improved accuracy. Finally, we show that the noniterative EnKF is sensitive to the size of time interval between the assimilation steps. Using the proposed iterative EnKF, results are more stable, more accurate reservoir models and predictions can be obtained even when a large time interval is used. This also indicates that iteration within the EnKF updating serves as a process that corrects the stronger nonlinear and non-Gaussian behaviors when larger time interval is used.
The Role of the Simulator in Drilling Operations
Authors: Millheim K. K. 
Published: December 2007

Summary
This paper presents a reference on the simulation industry—the state of the art, how the simulator is used, different types of simulators, and how simulator use applies to the drilling industry. For those contemplating buying or developing a simulator, this paper cites the uses and pitfalls of the simulator in drilling applications. This paper is intended to aid the engineer and manager in making decisions pertaining to the development, acquisition, or use of a drilling simulator.
Temperature-Dependent Relative Permeability and Its Effect on Oil Displacement by Thermal Methods
Authors: Nakornthap K. , Evans Ronald D. 
Published: December 2007

Summary
An analytical theory is presented that permits the formulation of a mathematical model to describe the variation of relative permeability with temperature in a water/oil system. The theory develops analytical equations for temperature-dependent relative permeability in terms of water saturation, irreducible water saturation, and differential change in irreducible water saturation with temperature. These equations predict and agree reasonably well with experimental results reported by other researchers.
The implications of temperature-dependent relative-permeability data on reservoir performance of a thermal process are also presented. These data together with the application of the Buckley-Leverett frontal-advance theory and the fractional-flow equation are used to predict oil recovery.
Steep Wave Forces on Large Offshore Structures
Authors: de St. Q. Isaacson Michael 
Published: December 2007

Abstract
A new numerical method for calculating the interaction of steep (nonlinear) ocean waves with large coastal or offshore structures of arbitrary shape is described. The evolution of the flow, and in particular the loads on the structure and the runup around it, are obtained by a time-stepping procedure in which the flow at each time step is calculated by an integral equation method based on Green's theorem.
A few comparisons are made with available solutions and results are presented for a typical design wave in shallow water. The method is capable of predicting forces caused by steep waves accurately and without prohibitive computer effort.
Comparison of Sodium Carbonate, Sodium Hydroxide, and Sodium Orthosilicate for EOR
Authors: Burk J. H. 
Published: December 2007

Summary
Alkaline and alkali/polymer flooding are economical and versatile techniques proposed for application in EOR. Recently, the use of high-pH alkaline chemicals was emphasized to obtain low interfacial tensions (IFT's) with the crude oil and to counteract alkali loss by both reservoir rock and interstitial water reactions. This experimental study compares the utility of sodium carbonate (Na2CO3) buffer solutions with sodium hydroxide (NaOH) and sodium orthosilicate (Na4SiO4) at equal Na2O levels for alkaline and alkali/polymer flooding.
The alkalis were found to be equally effective in reducing IFT with Wilmington Ranger zone crude, and eight other acid crude oils. Tertiary recovery results from 20 Berea corefloods with the Ranger zone crude and hard reservoir brine were equivalent (6 to 17%) for Na2CO3, NaOH, and Na4SiO4. Similar modest recoveries were obtained for polymer floods that used Polyacrylamide or xanthan gum. However, polymer augmentation of alkaline floods dramatically increased tertiary oil yields to 73 to 95%. In addition, alkali improved the injectivity of polymer solutions. The alkali reactions with sandstone were much less severe with Na2CO3 than with NaOH or Na4SiO4.
Comparison of an Improved Compositional Micellar/Polymer Simulator With Laboratory Corefloods
Authors: Camilleri Dominic , Fil Andre , Pope G. A. , Rouse B. A. , Sepehrnoori Kamy 
Published: December 2007

SummaryIn this paper, we compare numerical simulations made with our previously reported simulator with both our own and literature experiments. The most significant improvement concerns the phase behavior model used in the simulator. The new model approximately represents the phase behavior of pseudoquaternary mixtures containing surfactant, cosurfactant, oil, and brine. The different effects of sodium and calcium cations in the mixtures are accounted for with a new cation exchange model allowing for exchange with both clays and micelles. A tertiary oilflood experiment is reported that includes a more complete analysis of phase compositions and properties than generally available previously. Produced samples were analyzed for surfactant, alcohol, sodium, calcium, polymer, tritium, water, carbon-14-tagged decane, and decane. These analyses and pressure drop were compared with simulated behavior. Supporting physical property data were used as much as possible to estimate simulator input parameters rather than adjusting or "history matching" the results. Agreement with the most important features of the experiment was good. This agreement and good agreement with an experiment from the literature lead us to conclude that a significant improvement over previous efforts has been achieved. Especially noteworthy is our capability to account for the chromatographic separation of surfactant and alcohol.
Analytical Representation of the van Everdingen-Hurst Aquifer Influence Functions for Reservoir Simulation
Authors: Fanchi J. R. 
Published: December 2007

Abstract
Linear regression analysis has been used to develop some simple analytical expressions for the van Everdingen-Hurst aquifer influx influence functions. Regression results are presented for a variety of aquifer radius/reservoir radius ratios. The regression equations are designed for use in reservoir engineering applications, especially reservoir simulation.
Gravitational Effects During Diffusional Mass Transfer at the Pore Scale
Authors: Mahers Eric G. , Dawe Richard A. 
Published: December 2007

Summary
A novel approach to study and to quantify diffusional mass transfer at the pore scale is by holographic interferometry. This is a passive technique as information is obtained from what is occurring within the pores while the fluids in the pores are not physically disturbed. The porous media used were transparent micromodels with carefully designed two-dimensional (2D) network patterns where fluids could be readily trapped. The holograms of these micromodels were made by a wet-gate technique that ensured that they would not be moved during processing, and the live fringes were observed and recorded for subsequent analysis while the mass transfer processes occurred. Maps of lines of constant composition obtained over the whole pore showed the direction and rate of diffusion and any convective component of mass transfer.
This paper gives examples for both miscible and partially miscible systems and demonstrates that the alignment of the pores with respect to the gravitational field is a significant factor in the mass transfer. The correct modeling of the pore-scale mass-transfer phenomena is essential for proper scaling to reservoir EOR processes.
Glenn Pool Surfactant Flood Pilot Test: Comparison of Laboratory and Observation-Well Data
Authors: Bae J. H. , Patrick C. B. 
Published: December 2007

Summary
A surfactant flood pilot test was conducted in the William Berryhill lease of the Glenn Pool field, Creek County, OK. The test was conducted in the Upper sand in a 20-acre [8.1-ha], four-inverted-five-spot pattern. The field had been waterflooded and had a residual oil saturation of 30% PV.
A preflush preceded the surfactant slug, which was specifically formulated for this oil-wet reservoir. There were two observation wells in line between an injector and the central producer. Fluids from the observation well were periodically sampled and analyzed. A large oil bank observed in these wells had an oil cut of 40% or higher.
Despite chromatographic separation and changing sulfonate concentration and salinity, ultralow tension was maintained for a long period. The interfacial tension (IFT) behavior involving these variables was much more complex than expected. It was concluded that the process performance in the field as monitored in the observation wells was as good as expected from laboratory linear core test results.
Simple Frictional Analysis of Helical Buckling of Tubing
Authors: Mitchell R. F. 
Published: December 2007

Summary
Previous analyses of helical buckling of tubing have not considered frictional forces. In this paper, differential equations are derived and solved for two simplified cases of interest: downward motion of the tubing—e.g., when buckling occurs during the landing of the tubing—and upward motion of the tubing—e.g., when buckling occurs as a result of thermal and differential pressure loading subsequent to landing. While somewhat more complicated than the conventional frictionless buckling equations, these solutions are still suitable for hand calculations. These solutions, however, do not represent general solutions to buckling with friction. Load reversals and lateral frictional forces add complications that would require computer analysis. Several examples are examined to evaluate the relative importance of friction, which has a significant impact on tubing length change for loaded cases. For instance, the choice of a conservative value for the friction coefficient may allow the solution of a difficult seal-design problem by reducing a large predicted length change. Friction also has an important effect on set-down loads. Frictionless buckling calculations do not give conservative results for this problem.
Injection Well Logging Using Viscous EOR Fluids
Authors: Knight Bruce L. , Davarzani Mohammad J. 
Published: December 2007

Summary
A new tool has been developed that overcomes problems associated with logging injection wells in the presence of viscous fluids. The tool was evaluated in the laboratory and the field in water and polymer injection wells. Results indicate that the tool provides better information than conventional equipment. Special attention to log interpretation is required in zones where the flow pattern changes from turbulent to transition flow. A method is suggested to improve log interpretation that considers changes in flow regime.
Vertical Interference Testing Across a Low-Permeability Zone
Authors: Ehlig-Economides C. , Ayoub J. A. 
Published: December 2007

Summary
Bremer et al.1 described a mathematical model for analysis of a vertical interference test across a low-permeability zone. The test configuration called for recording wellbore pressure vs. time opposite one permeable layer while fluid is produced from the second permeable layer. The two permeable layers are separated by a tight zone of low vertical permeability. This paper offers a more general interpretation technique that allows for distinct properties in the two permeable layers and includes wellbore-storage and skin effects.
The purpose of the vertical interference test across a low-permeability zone is to determine the vertical permeability of the tight zone separating the two permeable strata. The results of such a test may influence well completion decisions for primary, secondary, and enhanced oil recovery. Of particular interest is the estimation of the fluid flow rate into or out of the packed-off layer.
Field test data have been analyzed with the new techniques. By including wellbore-storage and skin effects, the model presented in this study provides a much better fit with the data presented by Bremer et al.1 Because this method allows for determination of formation properties in both permeable zones, simultaneous recording of the pressures in both the producing and packed-off layers is recommended. Results indicate that the wellbore- pressure difference between the flowing and packed-off zones becomes constant after sufficient time and depends only on the permeabilities in the three zones. If wellbore-storage effects can be minimized, the behavior of pressure vs. log time may exhibit two distinct slopes: the first providing for calculation of the permeability in the flowing layer, and the second allowing calculation of the permeability in the packed-off layer. Type curves are presented for analysis of both the pressure and pressure-derivative transients.
The interpretation method is suitable for broader application than previous methods would allow. An important result is an estimate of the rate of crossflow between layers separated by a low-permeability zone.
Influence of Minor Components on Strength Development of 2CaO/SiO2-Silica Cement
Authors: Sasaki S. , Kobayashi W. , Okabayashi S. 
Published: December 2007

Summary
We have been accumulating the technical data on 2CaO/SiO2-silica cement as cementing material for deep oil wells and high-temperature geothermal wells. For this paper, we chose 21 inorganic compounds as minor components that are supposed to contaminate cement slurries at cementing and investigated their influence on strength development of 2CaO/SiO2-silica cement.
The early compressive strength of β-2CaO/SiO2-silica cement at 662°F [350°C] decreased remarkably with the addition of borates and hydroxides, but the strength of hardened specimens with 0.5 to 1.0% calcium chloride and magnesium chloride increased significantly. Also, we confirmed that the effect of the addition of minor components on β-2CaO/SiO2-silica cement was similar to that on γ-2CaO/SiO2-silica cement. Within this work, the strength of hardened specimens cured at 350°F [177°C] decreased with the addition of any inorganic compounds.
Design, Testing, and Planning Considerations for a 20-in. Record Casing String
Authors: Pejac R. D. , Fontenot E. P. 
Published: December 2007

Summary
During May 1984, a total of 12,455 ft [3800 m] of 20-in., 169-lbf/ft [51-cm, 2.47-N/m] C-95 casing was successfully run and cemented to the surface in L.W. Magoun No. 1, Concordia Parish, LA. The string consisted of 303 joints and required 49 hours to run. The casing weight in 9.7-lbm/gal [1162-kg/m3] mud was l.8×106 lbm [826 Mg].
This paper discusses the engineering, operational planning, and job execution for this world-record string of 20-in. [51-cm] casing. The topics include casing design, manufacturing, connection testing, and running and cementing procedures.
Bentonite Quality and Quality-Evaluation Methods
Authors: Bol G. M. 
Published: December 2007

Summary
Problems with bentonite quality and bentonite-quality-control methods have consistently been observed in the field in recent years. These problems are investigated and proposals are made on how to mitigate them. A number of commercial bentonites have been analyzed and their performances evaluated (1) to determine to what extent quality variations occur between commercial bentonites from different manufacturers, (2) to determine the cause(s) of these variations, and (3) to develop a proper quality-control method for bentonite.
The results show significant variations in quality between Oil Companies Materials Assn. (OCMA) and API-grade bentonite. The main cause of these variations is the different type and amount of extending chemical added.
Differences in rheology and fluid loss between bentonite suspensions in fresh water, seawater, and hydrogen-peroxide (H2O2) solutions give a quantitative measure of bentonite extension. Differences in performance before and after hot-rolling do the same.
Steam-Injection Profile Control Using Limited-Entry Perforations
Authors: Small G. P. 
Published: December 2007

Summary
A completion technique for steam-injection wells that ensures improved profile distribution of steam into several independent sands is being used at the South Belridge field in California. Previously, steam profiles were poor for many of the conventionally perforated (two ⅜-in. [9.5-mm] -diameter holes per foot) injection wells. This standard completion does not guarantee that the thicker, higher-permeability sands will not act as thief zones with respect to the thinner, tighter sands open in the same wellbore. Limited-entry perforating (typically one hole per 15 to 20 ft [4.6 to 6.1 m] of gross interval with at least one in each major sand member) provides the best assurance of achieving a uniform injection profile in single-wellbore multisand completions.