bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Gas Enrichment and Numerical Dispersion on Enriched-Gas-Drive Predictions
Authors: Stalkup Fred I. 
Published: December 2007

Summary
This paper examines the effect of gas enrichment in reservoir-scale enriched-gas-drive displacements through predictions made with a compositional simulator and the Peng-Robinson equation of state (PREOS). The calculations examine behavior for a classical three-component condensing-gas drive and for a 12-component reservoir-fluid characterization that predicts condensing/vaporizing-gas-drive behavior. The predictions also illustrate behavior for two simplified reservoir analogues: a homogeneous cross section with a low vertical/horizontal permeability ratio and a stratified cross section. An important feature of this study is that the impact of numerical dispersion on the predictions is assessed through numerical sensitivity calculations. The simulations show that (1) numerical dispersion causes an abnormally large, erroneous, predicted increase in recovery with increasing gas enrichment and a predicted incremental recovery over waterflooding that could be too large by as much as a factor of two; (2) the most realistic predictions are obtained by extrapolating recoveries to a gridblock size of zero, even though the extrapolation may be imprecise and the degree of convergence to the correct answer is unknown; (3) numerical dispersion causes too large a predicted increase in recovery with gas enrichment beyond the critical enrichment; and (4) calculated oil recovery vs. gas enrichment for the 3- and 12-component fluid characterizations studied is qualitatively similar for injection gases that give displacements ranging from highly immiscible to essentially first-contact miscible (FCM), although absolute differences in incremental recovery are sometimes as large as 1 to 2% of original oil in place (OOIP).
Rheology of Gas/Water Foam in the Quality Range Relevant to Steam Foam
Authors: Vries Arnold S. de , Wit Krijn 
Published: December 2007

Summary
Experimental results on the rheology of gas/water foam essentially show that if the gas flow rate is increased at an imposed water rate, the pressure gradient increases, reaches a maximum (the break point), and then decreases. A model for foam flow was formulated that explains this behavior semiquantitatively. It consists of a highly simplified model for foam in a single capillary coupled with a description for foam flow in a bundle of identical parallel capillaries. Below the break point, capillaries filled with foam occur with water-filled capillaries; above the break point, the water-filled capillaries are replaced by gas-filled capillaries.
A consequence of the model is that if one plots the results in a special way, a universal curve is obtained, dependent on only the porous medium and the fluid properties. The experimental data more or less conform to this curve, which can be used (in the same way as relative permeabilities) to predict pressure gradients for gas/water rates other than those experimentally measured. Consequences of the foam model for numerical simulation of foam flow are discussed.
Pressure-Transient Analysis of Arbitrarily Shaped Reservoirs With the Boundary-Element Method
Authors: Klkani Jitendra , Horne Roland N. 
Published: December 2007

Summary
Two boundary-element-method (BEM) formulations are proposed for the solution of pressure-transient problems in homogeneous, anisotropic reservoirs. Pressure solutions in arbitrary reservoir shapes with multiple sources and/or sinks and a variety of constant and/or time-dependent boundary conditions can be generated. This technique is superior to numerical methods because it preserves the analytical nature of the solution and because numerical dispersion and grid-orientation effects are nonexistent. Procedures for the convolution and Laplace-domain solution procedures are compared, and problems illustrating the various aspects of the BEM are solved.
Barium and Strontium Sulfate Solid-Solution Formation in Relation to North Sea Scaling Problems
Authors: Todd Adrian C. , Yuan Mingdong 
Published: December 2007

Summary
This paper presents the results of laboratory experiments carried out to investigate the formation of barium sulfate and strontium sulfate [(Ba, Sr)SO4] solid solution in multi-pressure-tapped cores. Two brines, one barium- and strontium-rich and the other sulfate-rich, were mixed in a core plug. Pressure differentials were measured and the changing permeability distribution along the core length was calculated. The morphology and chemical analysis of scaling crystals as shown by scanning electron microscopy (SEM) are presented. Results show a large extent of permeability damage caused by (Ba, Sr)SO4 solid solution deposits on the rock pore surface. The rock permeability decline and morphology and size of the scaling crystals indicate the influence of the supersaturations of BaSO4 and SrSO4 and the concentration ratio of barium to strontium ions.
Analysis off Gravity Separation in Freewater Knockouts
Authors: Powers Maston L. 
Published: December 2007

Summary
The selection of a freewater knockout depends on the desired performance. The design criterion developed here is based on the perception that most FWKO's are installed to remove the bulk of the water from a high-water-cut flow stream so that the oil can be dehydrated economically to salable specifications and to discharge water requiring minimal treatment before disposal. Only the gravity separation process is considered; the contribution of coalescing devices is excluded. Vertical FWKO's are discussed briefly, but the bulk of this paper is devoted to horizontal FWKO's, which constitute a majority of vessels. Hydraulic similarity of horizontal FWKO's and API separators is demonstrated, and a design criterion for FWKO's is developed with the basis used in the design development for API separators. This analysis discloses that commonly used criteria overrate the ideal flow capacity of FWKO's by a factor of 4/π. It shows that maximum FWKO capacity occurs when the oil/water interface is maintained at a level of 0.769 diameters in the case of ideal vessels and somewhat higher for nonideal vessels, rather than 0.50 as commonly believed. Published FWKO residence-time distributions (RTD's) indicate nonideal flow. Consequently, a design allowance for short-circuiting and turbulence effects was incorporated into the FWKO design. The effect of vessel proportions on cost per unit capacity is analyzed and an equation is developed for determining optimum proportions.
The Effect of Viscous Fluid Properties on Excess Friction Pressures Measured During Hydraulic Fracture Treatments
Authors: Holditch Stephen A. , Robinson Brad M. , Ely John W. , Rahim Zillur 
Published: December 2007

Summary
A plot of excess pressure vs. time can be used to predict fracture-growth patterns only when both the viscosity of the fluid in the fracture and the stress at the fracture tip remain constant. This paper uses laboratory data and field examples to explain how increased friction owing to viscous slurries affects the interpretation of fracturing pressures.
A New Model for Two-Phase Oil/Water Flow: Production Log Interpretation and Tubular Calculations
Authors: Hasan A. Rashid , Kabir C. Shah 
Published: December 2007

Summary
This work presents the results of an experimental and theoretical investigation of two-phase oil/water flow behavior in vertical pipes. Bubbly flow is observed to be the predominant flow pattern, although at high flow rates, slug flow was noted. The proposed method, developed from the drift-flux principle, is validated by our experimental data and those obtained from other sources. Limited study indicates the proposed method's superiority over others available in the literature. This work further shows the error involved when oil/water flow behavior is predicted by homogeneous, gas/liquid, and constant-slip models. Application of the model for production log interpretation is also documented.
Recent Performance of the Dual-Resistivity MWD Tool
Authors: Grupping Theo I. F. , Wagstaff J. D. 
Published: December 2007

Summary
The dual-resistivity MWD tool uses sections of the drill collar as electrodes and provides two independent resistivity measurements: a principal well-focused lateral measurement of the current flowing radially from a defined segment of the drill collar and a secondary axial or bit measurement of the current flowing from a defined portion of the lower bottomhole assembly (BHA). In oil-based muds, a single (bit) measurement is made of the current flowing to the formation through the drill bit.
Optimal Input Design—A Method for Enhancing Data Quality
Authors: Foss Bjarne A. 
Published: December 2007

Summary
This paper presents a generic design method for specifying the flow sequence from one or multiple wells. The method seeks to maximize the information content in collected data. It is shown how the information content, defined in precise terms, is a function of the flow sequence. Three examples demonstrate how the proposed method improves data quality, and guidelines for practical use are presented.
Physics and Modeling of Thermal Flow and Soil Mechanics in Unconsolidated Porous Media
Authors: Settari Antonin 
Published: December 2007

Summary
This paper describes a new formulation of nonlinear soil mechanics and multiphase thermal flow. The nonlinearities of the soil behavior and their interactions with fluid flow causing shear failure of the soil are the dominant features of the process. The numerical formulation of the coupled flow/stress solution model includes nonlinear compressibility and flow properties as functions of pressure, stress, and temperature; nonlinear, incremental, thermal poroelastic stress analysis; and shear or tensile failure and its effects on transport properties, porosity, and stress. An efficient sequential numerical scheme was developed. It is mass conservative and applicable to external coupling of existing simulators. The 1D examples show some startling new features of reservoir mechanics in unconsolidated media.
Effect of the Presence of Oil on Foam Performance: A Field Simulation Study
Authors: Law D. H. -S. , Yang Z. -M. , Stone T. W. 
Published: December 2007

Summary
This paper describes a field-scale sensitivity study of the effect of the presence of oil on foam performance in a steam-foam-drive process. The 2D field-scale simulation was based on a field pilot in the Karamay formation in Xin-Jiang, China. Numerical results showed that the detrimental effect of oil on the foam performance in field operations is significant. The success of a steam-foam process depended mainly on the ability of the foam to divert steam from the depleted zone.
Calculating the Effective Permeability Tensor of a Gridblock
Authors: Kasap Ekrem , Lake Larry W. 
Published: December 2007

Summary
We propose an analytical method to calculate effective block permeabilities as a full tensor based on the geometry, block size, full local tensorial permeabilities, and the geology within the block. The method was validated with a finite-element numerical simulator and was applied to a simulation of flow through an outcrop of the eolian Page sandstone. Results show that the relative positions of the main geologic features and the ratio between the grain-flow and wind-ripple permeabilities are more important than bounding surfaces and dispersion in determining flow behavior.
Volumetric Treatment Efficiencies of Some Commercial Clay Stabilizers
Authors: Hesterberg Dean , Reed M. G. 
Published: December 2007

SummaryVolumetric treatment efficiencies of three commercially available clay-stabilizer treatments were evaluated in the laboratory. Rock volume treated per unit chemical volume varied up to three-fold between stabilizers and depended on sandstone mineral properties. The results are valuable for designing clay-stabilizer treatments and maximizing stabilizer cost-effectiveness.
A Bayesian Methodology for Estimating Relative Permeability Curves
Authors: Yang P. -H. , Watson A. T. 
Published: December 2007

Summary
Among the various properties important for simulating reservoir behavior, relative permeability curves may be the most poorly determined by current methods. This paper presents a method for obtaining improved estimates of relative permeability curves. A Bayesian-type performance index is used to incorporate prior estimates of relative permeability curves into an automatic history-matching algorithm. Estimates obtained with the method are consistent with the reservoir production and yet conform to the prior estimates.
A Practical Equation of State
Authors: Ahmed Tarek 
Published: December 2007

Summary
To use the Peng-Robinson equation of state (PREOS) to predict the phase and volumetric behavior of hydrocarbon mixtures, one needs to know the critical pressure, pc, critical temperature, Tc, and acentric factor, ω, for each component present in the mixture. For pure compounds, the required properties are well-defined, but nearly all naturally occurring gas and crude oil fluids contain some heavy fractions that are not well-defined and are not mixtures of discretely identified components. These heavy fractions often are lumped and called the "plus fraction" (e.g., C7+ fraction). Adequately characterizing these undefined plus fractions in terms of their critical properties and acentric factors has long been a problem. Changing the characterization of the plus fraction can have a significant effect on the volumetric and phase behavior of a mixture predicted by the PREOS. This limitation of the PREOS results from an improper procedure of determining coefficients a, b, and α for the plus fraction and for hydrocarbon components with critical temperatures less than the system temperature (i.e., methane and nitrogen). This paper presents a practical approach to calculating the parameters of the PREOS for the undefined fractions to improve the predictive capability of the equation. Use of the modified equation is illustrated by matching laboratory data on several crude oil and gas-condensate systems.
Rate Performance of a Layered Reservoir With Unsteady-State Interlayer Crossflow
Authors: Olarewaju J. S. , Lee W. J. 
Published: December 2007

Summary
This paper presents an analytical solution for rate performance of a well intercepting a bounded two-layer reservoir. The solution is for modeling two-layer reservoirs with or without crossflow, with each layer having different layer skins and drainage radii. We present the effects of partial completion and of different layer skins and drainage radii on the rate behavior in layered reservoirs.
Case Studies off the Bending Vibration and Whirling Motion off Drill Collars
Authors: Vandiver J. Kim , Nicholson James W. , Shyu Rong-Juin 
Published: December 2007

Summary
This paper describes two principal sources of bottomhole-assembly (BHA) bending vibration: (1) drill-collar whirling and (2) linear coupling between weight-on-bit (WOB) fluctuations and bending vibration of an initially curved BHA. It also evaluates the consequences of bending vibration in terms of drill-collar wear and connection fatigue. Equations are given for forward and backward whirl rate and for tangential velocity at the borehole wall. Downhole measurements of bending moment are used to detect and to identify bending-vibration events, and data taken with a downhole vibration-measurement system are used to illustrate cases of linearly coupled bending vibration, forward and backward whirl, and bit bounce.
Improvement of Drill-Collar Fatigue Property by Last-Engaged-Thread-Height Reduction of Pin
Authors: Tsukano Yasushi , Nishi ShunJi , Nishida Shin-Ichi , Ueno Masakatsu 
Published: December 2007

Summary
This paper describes a method to increase the fatigue life of a drill collar by reducing the height of a pin's last-engaged thread (LET). The effectiveness of the method was verified with finite-element analysis (FEA), and the results were evaluated by full-size fatigue tests. Also, the practicality of the redesigned connection was confirmed through overmakeup, make-and-break, and full-size tensile testing.
Hydraulic Fracturing Slurry Transport in Horizontal Pipes
Authors: Shah Subhash N. , Lord David L. 
Published: December 2007

Summary
Horizontal-well activity has increased throughout the industry in the past few years. To design a successful hydraulic fracturing treatment for horizontal wells, accurate information on the transport properties of slurry in horizontal pipe is required. Limited information exists that can be used to estimate critical deposition and resuspension velocities when proppants are transported in horizontal wells with non-Newtonian fracturing gels.
This paper presents a study of transport properties of various hydraulic fracturing slurries in horizontal pipes. Flow data are gathered in three transparent horizontal pipes with different diameters. Linear and crosslinked fracturing gels were studied, and the effects of variables—e.g., pipe size; polymer-gelling-agent concentration; fluid rheological properties; crosslinking effects; proppant size, density, and concentrations; fluid density; and slurry pump rate—on critical deposition and resuspension velocities were investigated. Also, equations to estimate the critical deposition and resuspension velocities of fracturing gels are provided.
Laboratory and Field Evaluations of Clad Christmas Tree Equipment
Authors: Sisak W. J. , Gordon J. R. 
Published: December 2007

Summary
A methodology is presented for evaluating the corrosion resistance of clad equipment in sour environments. This paper describes the laboratory and field test programs used to evaluate the suitability for sour service of gate valves clad with Alloy UNS N06625 by weld overlay and by hot, isostatic pressing (HIP). The laboratory tests used to evaluate corrosion and cracking resistance of the clads are reviewed. Experience with actual field installations of both types of clad valves is presented, and the test/inspection methods used to evaluate the equipment during and after the service period are discussed. Finally, laboratory and field results are compared to highlight key findings related to the clad valve bodies and to the trim components.
Comparison of Laboratory and In-Situ Measurements of Waterflood Residual Oil Saturations for the Cormorant Field
Authors: van Poelgeest Frits , Niko Helmut , Medwld Andrew R. 
Published: December 2007

Summary
Shell Expro and Koninklijke/Shell E&P Laboratorium (KSEPL) have been engaged in a multidisciplinary effort to deter mine the waterflood residual oil saturation (ROS) in two principal reservoirs of the Cormorant oil field in the U.K. sector of the North Sea. Data acquisition included special coring and testing. The study, which involved new reservoir-engineering and petrophysical tech niques, was aimed at establishing consistent ROS values.
Reservoir-engineering work centered on reservoir-condition corefloods in the relative-permeability-at-reservoir-conditions (REPARC) apparatus, in which restoration of representative wettability conditions was attempted with the aging technique. Aging results in a con sistent reduction of water-wetness of all core samples. The study indicated that ROS values obtained on aged cores at water throughputs of at least 5 PV represented reservoir conditions. The petrophysical part of the study involved ROS estimation from sponge-core analy sis and log evaluation.
A Newly Developed Chromium(lll) Gel Technology
Authors: Sydansk Robert D. 
Published: December 2007

Summary
Laboratory testing of a recently developed chromium(III) [Cr(III)] gel technology is reported. The gels can be used in conjunction with a number of oilfield treatments. The single-fluid acrylamide-polymer/Cr(III)-carboxylate aqueous gels are formed by crosslinking acrylamide polymer with a Cr(III)-carboxylate-complex crosslinking agent. Representative gel compositions and associated gel properties are discussed.
An Experimental Study of the Annulus Pressure Drop in a Simulated Air-Drilling Operation
Authors: Supon S. B. , Adewuml M. A. 
Published: December 2007

Summary
A comprehensive experimental wellbore model was built to simulate the multiphase flow of compressed air and sand that occurs in an air-drilling process. The model was designed to control the air volumetric flow rate and sand mass flow rate through a transparent annulus. The model also permitted observation of the sand and air in the annulus and allowed measurement of the pressure drop across the annulus. An empirical equation was developed for the minimum annulus pressure drop as a function of the sand mass flow rate through the system, the optimum annulus air velocity, the weight fraction of coarse sand particles entering the annulus, the weight fraction of coarse sand particles in the annulus, and solids loading in the annulus. The experimental results were compared with annulus pressures predicted by a semiempirical model of the air-drilling process developed by Angel. Angel's model failed to predict the observed minimum annulus pressure drops. In addition, the experimental results indicated that an annulus air velocity lower than the value assumed by Angel's model may be required.
New System Provides Continuous Quantitative Analysis of Gas Concentration in the Mud During Drilling
Authors: Roberts G. L. , Kelessidls V. C. , Williams J. M. 
Published: December 2007

Summary
Continuous monitoring of hydrocarbon gases in drilling fluids at the surface is essential for identification of prospective reservoir zones as well as for safety. This paper describes a new gas-analysis system that determines the total amount of gas in the mud below the bell nipple. The system is continuous, consistent, and fully quantitative (unlike a gas trap) but not labor-intensive (like a steam still). It also recovers and analyzes gas liberated into the air at the bell nipple, which test results have shown to be almost 50% of the total gas in the mud below the bell nipple.
Permeability Reduction Induced by a Nonhydrostatic Stress Field
Authors: Holt Rune M. 
Published: December 2007

Summary
Stress-dependent permeability was measured in a high-porosity/high-permeability sandstone with mechanical and fluid-flow parameters similar to those found in typical North Sea reservoirs, particularly the little-investigated effect of triaxial stress configurations. Hydrostatic loading from atmospheric conditions to stress levels comparable to those found in situ causes a slight permeability reduction. When the applied stress is nonhydrostatic, the permeability decrease is more pronounced. In particular, as failure is approached in triaxial loading or unloading, the permeability may be significantly reduced (in some cases to &lt; 10% of its initial value). This paper discusses the consequences of these results for interpretation of standard permeability measurements. An example quantifies the formation damage (skin) induced by the near-wellbore stress field.
Modeling Low Interfacial Tension Hydrocarbon Phenomena in Porous Media
Authors: Gray Jane D. , Dawe Richard A. 
Published: December 2007

SummaryThis paper investigates pore-scale mechanisms of both wetting and nonwetting phase dropout and flow at low interfacial tensions (IFT's) (approximately 0.1 to &lt; 0.01 mN/m) by use of transparent 2D micromodels with a partially miscible binary fluid system. Quantification is possible with this liquid system because it has uniquely defined physical properties at any given temperature. Phase dropout and flow behavior at phase saturations of &lt; 10% are emphasized. Wettability effects are dominant, but the fluid/fluid interactions change as the IFT drops. The ramifications for the relative permeability curves are discussed.