bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous Estimation of Relative Permeabilities and Capillary Pressure
Authors: Chardaire-Rivière Catherine , Chavent Guy , Jaffré Jérôme , Liu Jun , Bourbiaux Bernard J. 
Published: December 2007

Summary
An automatic numerical method is proposed for simultaneous determination of relative permeabilities and capillary pressure from the results of a single two-phase flow experiment in a range of velocities representative of field flow conditions. The experiment is a standard imbibition or drainage displacement with an imposed difference of pressure or flow rate. The experimental data used are the outlet production, the pressure drop between the two faces, and local saturation profiles at different times along the core. Relative permeabilities and capillary pressure are estimated with a least-squares technique. Use of a high-order numerical scheme significantly reduces the numerical diffusion. The optimal control theory is used to solve the minimization problem. The corresponding FORTRAN code is generated by a symbolic program. The validity of the method first is demonstrated with simulated data, then is tested in two laboratory experiments: one imbibition and one drainage. Good agreement is obtained for both situations.
Experimental Investigation of Critical Condensate Saturation and Its Dependence on Interstitial Water Saturation in Water-Wet Rocks
Authors: Danesh Ali , Henderson G. D. , Peden J. M. 
Published: December 2007

SummaryAn experimental investigation of retrograde condensation in water-wet pores was conducted in micromodels and long cores to determine the critical condensate saturation and to evaluate the significance of interstitial water on condensate mobility. Although the interstitial water lowered the critical condensate saturation, it also could reduce the initial recovery rate by restricting condensate drainage.
Good Wells Make the Best Candidates for Well Stimulation
Authors: Jennings A. R. 
Published: December 2007

Summary
When such factors as well response, return on stimulation costs, well cleanup, and sustained productivity are considered, it often becomes apparent that good wells are viable candidates for well stimulation. This paper discusses critical factors related to well-stimulation success, emphasizes that good wells possess the majority of these characteristics, and illustrates technical points with case histories.
Barium and Strontium Sulfate Solid-Solution Scale Formation at Elevated Temperatures
Authors: Todd A. C. , Yuan M. D. 
Published: December 2007

Summary
Barium sulfate scale occurrence is a severe production problem in North Sea oil operations. Barium sulfate is often accompanied by strontium sulfate to form a completely mixed scale called (Ba, Sr)SO4 solid solution. This paper describes a laboratory study carried out at 70°C to examine (Ba, Sr)SO4 solid-solution scale formation in porous media and the formation damage resulting from the mixing of two incompatible waters. The paper is a continuation of the previously reported room-temperature work. Results of experiments carried out at the elevated temperatures again demonstrate that substantial scale deposition can occur in a rock core and can cause considerable decline of rock permeability as a result of concurrent flowing of two incompatible waters.
Effect of Wellbore Storage on the Analysis of Multiphase-Flow-Pressure Data
Authors: Hatzignatiou D. G. , Peres A. M. M. , Reynolds A. C. 
Published: December 2007

SummaryThis paper investigates the effect of wellbore storage on the analysis of pressure drawdown data obtained at a well producing a solution-gas-drive reservoir. Wellbore storage effects are incorporated by specifying a sandface oil flow rate that increases exponentially from zero to the specified constant value of the oil flow rate at the surface. Use of new computational equations derived here shows that effective oil permeability as a pointwise function of pressure can be computed directly from the measured values of the flowing wellbore pressure, provided the sandface oil flow rate is measured and incorporated into the analysis. If the sandface flow rate is unknown, effective permeability can be computed only after wellbore storage effects become negligible. In all cases, a semilog plot of wellbore pressure squared vs. time is shown to be a viable method for estimating effective oil permeability at initial conditions, effective oil permeability at the final flowing wellbore pressure value, and mechanical skin factor.
Cement Channeling: How to Predict and Prevent
Authors: Lockyear Christopher F. , Ryan Daniel F. , Gunningham Marcus M. 
Published: December 2007

Summary
This paper describes experiments with a large-scale flow loop (45 ft of 7-in. pipe in nominal 8½-in. open hole) that measure the velocity of the interface between fluids of varying densities and rheologies. The work showed that single-fluid velocity profiles cannot be used to predict interfacial profiles (e.g., between spacer and cement) and confirmed the importance of turbulent flow in minimizing channeling through mechanisms of increased frictional pressure drop and mixing across the annulus. Large density differences, both negative and positive, also minimized channeling.
An Analysis of Miscible Flooding Chase-Fluid Strategies
Authors: Walsh M. P. 
Published: December 2007

Summary
This paper presents a fractional-flow-theory analysis of miscible flooding chase-fluid strategies. Graphical solution methods to analyze flood performance for arbitrary solvent/water ratios, chase gas/water ratios (GWR's), and solvent slug sizes are presented. The graphical solution techniques include methods to predict the effects of wave interference, an important precursor to oil-bank destruction or loss in mobility control. An examination of interference leads to a deeper understanding of the miscible slug process. The advantages and disadvantages of chase-water, chase-gas, and simultaneous chase-gas/water injection are summarized. The analysis provides the theoretical basis for many chase-fluid design practices, including the idea of a minimum solvent slug size to ensure displacement integrity and the concept of an optimal chase GWR to minimize solvent requirements.
Evaluation of Steam Resistance of Gravel-Packing Materials
Authors: Weaver J. D. , Knox J. A. 
Published: December 2007

SummaryThis paper compares the steam stability of common gravel-packing materials. The scope was limited to one set of down-hole conditions. Results indicated that none of the commonly used materials were entirely satisfactory, but another material not normally used in the petroleum industry was found to give excellent results.
Mathematical Simulation of Phase Behavior of Natural Multicomponent Systems at High Pressures With an Equation of State
Authors: Brusilovsky A. I. 
Published: December 2007

Summary
This paper presents the new general cubic equation of state (EOS) for predicting phase and volumetric behavior of natural multicomponent systems under pressure and temperature conditions that conform to reservoir engineering processes. A new effective method to calculate the critical pressure of C5+ or C7+ fractions in reservoir fluids is presented. The method is of great importance for successful simulation at pressures greater than 25 MPa and can be used with any cubic EOS. The results of the mathematical simulation are described and the effects of porous media on phase behavior for natural multicomponent systems and of capillary pressure on dew- and bubblepoint parameters are investigated.
Miscible-Gasflood-lnduced Wettability Alteration: Experimental Observations and Oil Recovery Implications
Authors: Yeh S. W. , Ehrlich Robert , Emanuel A. S. 
Published: December 2007

Summary
We present visual cell and coreflood data pertaining to the influence of water saturation on miscible gasflood residual oil (water blocking). In visual cell studies, we equilibrate miscible gases and oils at reservoir conditions with an intervening water phase. We find that the solvent-induced deposition of separated solids causes initially water-wet quartz surfaces to become oil-wet. A number of miscible coreflood displacements at high water saturation are considered, and the extent of water blocking is determined for Berea sandstone and reservoir cores.
Displacements of fluid systems with wettability alteration and those of refined oil systems without wettability alteration are reported. We find that water-blocking measurements with pure hydrocarbons overestimate miscible flood Sor regardless of the porous medium (Berea or reservoir sandstone or a reservoir carbonate) and the flood (CO2 or hydrocarbon miscible). We further find that water blocking is significantly more severe in Berea sandstone than in reservoir rock. We assert that water-blocking measurements with refined oil systems in Berea sandstone greatly overestimate water blocking in reservoirs, partially because refined oils cannot reproduce miscible-flood-induced wettability alteration.
Theoretical Study of Water Blocking in Miscible Flooding
Authors: Müller Thomas , Lake Larry W. 
Published: December 2007

Summary
Miscible displacement processes can leave a substantial amount of residual oil behind the displacement front. This phenomenon has two general causes: instabilities caused by local heterogeneities or viscous fingering and water blocking. This paper describes a study of the latter. Numerous laboratory experiments have shown that significant blocking of oil from the solvent by mobile water can occur in water-wet media and at large water saturations. Despite this, water-blocking studies have been limited to either simple correction functions in numerical simulations or microscopic models. To the best of our knowledge, no explicit theoretical model considers the macroscopic bypassing and subsequent interaction of the solvent stream with a trapped hydrocarbon phase.
In this study, CO2 is the miscible solvent. A numerical model calculates the mass flux between flowing and stagnant regions separated by a water film. The model considers solvent diffusion and diffusional extraction of oil accompanied by swelling or shrinking of the stagnant hydrocarbon phase. The various process parameters are represented by a set of dimensionless numbers, which allow the problem to be scaled to any size. We show that the conditions for the mobilization of water-trapped oil are determined essentially by two numbers: the ratio of the stagnant water/oil volumes and the ratio of the solvent equilibrium constants at the phase boundaries. We apply the model to published laboratory miscible flood experiments. The water-film thickness is used as a matching parameter to reproduce closely the measured residual oil data for different flood velocities. Results indicate that solvent diffusion and oil swelling mechanisms effectively account for trapped oil on the laboratory scale. Trapping rapidly decreases at field scale if larger water barriers exist.
Significance of Quality Control of Liner-Wall Symmetry on Shaped-Charge Perforator Performance
Authors: Kececloglu Iflyenia 
Published: December 2007

SummaryThe objectives of this investigation were to demonstrate experimentally the significance of liner-wall mass uniformity and concentricity on the penetrating effectiveness (total target penetration and target hole size and symmetry) of conical shaped charges and to devise a systematic approach for selecting the optimum manufacturing conditions for the production of acceptably uniform shaped-charge liners. Experimental results indicated that total target penetration decreased with increasing liner-wall mass nonuniformity. Moreover, a statistical quality-control method was implemented to investigate systematically the variation in the symmetry of newly produced liners as a function of several manufacturing parameters, such as die vibration, die rotation, die pressing loads, and die dwelling/shaping times.
Empirical Correlations of Saturated Steam Properties
Authors: Chien Sze-Foo 
Published: December 2007

Summary
Both steamdrive and steam stimulation processes for EOR involve thermodynamic and transport properties of steam. These properties have roles in the fluid flow, heat transfer, and mass and heat balances of recovery processes. Hence, they affect, not only the operation of the process, but also the economics and management of the oil recovery project. This paper presents empirical correlations of thermodynamic and transport properties of saturated steam in dimensionless forms as functions of either reduced temperature or reduced pressure. The pressure range of the correlations extends from atmospheric to 3, 000 psia [20.7 MPa]. The properties include saturation temperature, saturation pressure, specific volume, specific enthalpy, specific entropy, isobaric specific heat, dynamic viscosity, thermal conductivity, dielectric constant, surface tension, and isentropic expansion exponents. Compared with values listed in current steam tables, the calculated properties are accurate within ±0.02 % for saturation temperature and pressure, within ±0.12 % for thermodynamic properties, and within ±0.27% for transport properties.
Modeling Annular Flow Behavior for Gas Wells
Authors: Alves I. N. , Caetano E. F. , Minami Kazuloshl , Shoham Ovadla 
Published: December 2007

Summary
A mechanistic model is developed for the prediction of annular two-phase flow behavior in gas wells. The model can predict annular flow characteristics, such as liquid film thickness, gas void fraction, and pressure gradient. It was evaluated against a data bank of 75 wells for which the pressure drop between the bottom of the well and the wellhead was available. The model was also compared with data from two wells with measured pressure profiles. Model predictions are in agreement with these data and superior to most commonly used correlations.
Hole Cleaning in Full-Scale Inclined Wellbores
Authors: Sifferman T. R. , Becker T. E. 
Published: December 2007

Summary
A 4-year multifactor experimental study was completed recently on hole cleaning in inclined wellbores. Ten variables-annular mud velocity, mud density, mud rheology, mud type (oil- or water-based), cuttings size, rate of penetration (ROP), drillpipe rotary speed, drillpipe eccentricity, drillpipe diameter, and hole angle-were studied over a range of values. The full-scale annular test section was 60 ft [18.3 m] long, with 3- and 4.5-in. [76- and 114-mm] drillpipe in an 8-in. [203-mm] ID (wellbore diameter). Hole angle varied from 45 to 90° from vertical. Results frequently showed a large buildup of cuttings in the annulus, and cuttings were difficult to remove once a bed had built up on the low side of the wellbore. Cuttings-bed sliding also was more intense than anticipated. Mud velocity and mud density have the greatest effect on hole cleaning. Several two- and three-factor variable interactions also emerged from a subsequent statistical analysis.
The Use of Filtration Theory in Developing a Mechanism for Filter-Cake Deposition by Drilling Fluids in Laminar Flow
Authors: Flsk J. V. , Shaffer S. S. , Helmy Samy 
Published: December 2007

Summary
This paper presents a mechanism for filter-cake deposition by drilling fluids in laminar flow. The mechanism evolved from analysis of filtration-data plots obtained from two linear equations derived from filtration theory. With these plots, various fluid-loss additives were evaluated on their ability to form a low-permeability filter cake that can be eroded by a fluid in laminar flow. The mechanism was tested on two wells with high torque and drag, and the static API high-temperature/high-pressure (HTHP) values were minimized.
NMR Imaging of Pore Structures in Limestones
Authors: Gleeson James W. , Woessner Donald E. , Jordan Clif F. 
Published: December 2007

SummaryNuclear-magnetic-resonance (NMR) imaging was used to examine pore structures and liquid flow paths in rocks nonde-structively. Various pore types were recognized in a spectrum of limestones, including growth-framework, moldic, vuggy, between-particle, and within-particle porosities. Pore connectivity was examined by fluid displacement and flow-weighted and 3D imaging.
Effect of Oxidation-Reduction Condition on Wettability Alteration
Authors: Wang Fred H. L. , Guidry Larry J. 
Published: December 2007

Summary
This paper presents results of a laboratory study exploring the effect of the oxidation-reduction (redox) condition on crude-oil adsorption on rock mineral surfaces and consequent wettability alteration. Experiments were performed by aging Berea outcrop and Loudon reservoir sandstones with crude oil under various redox conditions and water saturations. Wettability alterations after aging were evaluated by the U.S. Bureau of Mines (USBM) method and by waterflood tests. The natural, oxidized Berea cores changed from strongly water-wet to mixed-wet conditions when aged at irreducible water saturation. Wettability alteration was greatly reduced when aging experiments were conducted under reduced conditions. The degree of wettability alteration depended on availability and redox state of iron on the mineral surfaces and also on aging time. We suggest two possible mechanisms to explain the role of iron in the wettability-alteration process. Wettability alteration in the water-wet Berea cores was insignificant when the cores were aged at residual oil saturation (ROS). Wettability alteration was also insignificant in the mixed-wettability Loudon reservoir cores, regardless of the water saturation or redox condition used in the aging experiments. We present the implications of these findings on core-handling procedures for wettability preservation.
Fractured Reservoir Characterization Through Injection, Falloff, and Flowback Tests
Authors: Peng C. P. , Singh P. K. , Halvorsen Hugo , York S. D. 
Published: December 2007

Summary
This paper presents the development of a multiphase pressure-transient-analysis technique for naturally fractured reservoirs and the analysis of a series of field tests performed to evaluate the water injection potential and the reservoir characteristics of a naturally fractured reservoir. These included step-rate, water-injectivity, pressure-falloff, and flowback tests. Through these tests, a description of the reservoir was obtained.
The Design of Pulsed-Neutron Reservoir-Monitoring Programs
Authors: Kimminau S. J. , Plasek R. E. 
Published: December 2007

Summary
The use of pulsed-neutron logs to infer fluid saturations behind casing in both stand-alone and time-lapse modes depends on the reproducibility of the intrinsic cross-section measurement. Experimental and field results from North Sea and North Slope fields show how imprecision and inaccuracy vary with conditions. A general design checklist is presented.
Impact of Flow-Unit Reservoir Description on Simulated Waterflood Performance
Authors: Silseth J. K. , MacDonald A. C. , Alvestad Jostein , Buller A. T. , Torp S. B. 
Published: December 2007

Summary
The impact on simulated waterflood performance of adopting a "discrete" and simplified flow-unit representation of reservoir heterogeneity, rather than a conventional "smooth" model based on contouring of petrophysical zonal averages, was assessed with a synthetic model of a heterogeneous barrier-bar sand body. On the basis of comparative simulations, the contour models did not generate consistently optimistic predictions of reservoir performance (compared with their flow-unit counterparts). Individual well behavior, however, varied significantly according to model type.
Modeling Forces on a Beam-Pump System During Pumping of Highly Viscous Crude
Authors: Lea J. F. 
Published: December 2007

SummaryIn previous dynamic predictive models of beam-pump performance, drag forces on the rod string commonly are modeled by an input empirical drag coefficient multiplying the local rod velocity. This paper shows how forces on the rods and pump plunger can be modeled theoretically and calculated for viscous flow. Results of viscous-flow calculations to develop drag coefficients compare well with measured field data.
Normalization of Nitrogen-Loaded Gas-Lift Valve Performance Data
Authors: Nieberding M. A. , Schmidt Zelimlr , Blais R. N. , Doty D. R. 
Published: December 2007

Summary
The flow performance of two nitrogen-loaded gas-lift valves and one combination gas-lift valve was tested under simulated downhole conditions. Set pressures up to 1, 500 psig and injection pressures up to 1, 650 psig yielded a maximum observed gas flow rate of 3.6 MMscf/D. Pressure-operated valve performance depends on injection pressure for specific production and dome pressures, valve geometry, and other factors. Two performance characteristics, separated by the test-rack opening pressure, are observed: throttling and orifice flows. Semimechanistic models predict throttling and orifice flow performance. Experimental performance characteristics tune the model for any port size used in the Camco R-20 valve.
Flow-Related Corrosion in Large-Diameter Multiphase Flowlines
Authors: Green A. S. , Johnson B. V. , Choi H. J. 
Published: December 2007

Summary
A strong relationship between field measurements of flow regime and corrosion rate has been found. In multiphase flow, the slug flow regime produces high liquid velocities and high inherent turbulence levels for significant periods. The exact mechanism for removing a corrosion-inhibitor film from a pipe wall or preventing the film from forming remains unclear, but high turbulence and wall shear stresses always are present when flow-related corrosion occurs. The levels of wall shear stress may be estimated for a variety of pipeline features when subject to a passing slug. This provides a basis for realistic corrosion-inhibitor trials in the laboratory and a means of relating this information to field conditions. The onset of slug flow may be predicted to identify those times when a flowline may be especially at risk.
History Match of Multiwell Simulation Models of the Cyclic Steam Stimulation Process at Cold Lake
Authors: Boberg T. C. , Rotter M. B. , Stark S. D. 
Published: December 2007

Summary
Various simulation model elements were examined in an effort to match observed behavior of a selected steam stimulation well at Cold Lake. The best match required a large model encompassing eight wells, but a three-well model provided an adequate match. Well location, fracture angle, and geology must be represented accurately.
A Superposition Method for Representing Wellbore Crossflow in Reservoir Simulation
Authors: Modine A. D. , Coats K. H. , Wells M. W. 
Published: December 2007

Summary
Production from highly stratified reservoirs can result in significant crossflow between layers through wellbores. This paper describes a new, relatively simple superposition method to represent this, crossflow in a numerical simulator. The method calculates vertical wellbore saturation variations throughout the wellbore and gives more accurate results than a fully mixed wellbore method. Equations are given for the new method, a fully mixed wellbore method, and the exact solution for crossflow in a well completed in a column of gridblocks. Three examples, including a field-scale depletion, are given comparing exact results with those from the superposition and fully mixed wellbore methods.