bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Electrostatic Approach to the Association of Sodium and Calcium With Surfactant Micelles
Authors: Hirasaki George J. , Lawson J. B. 
Published: December 2007

Summary
Association of sodium and calcium with surfactant micelles was measured and electrostatic models were used to interpret the experimental results. It was hypothesized that the association of calcium with micelles having sulfonate or sulfate anionic groups can be described by electrostatics alone—i.e., specific chemical associations were not considered. Interpretation of data obtained with ultrafiltration (UF) membranes that separate free electrolyte solution from micelles supports this hypothesis.
Two parameters estimated for the electrostatic model were the lengths of the hydrophilic groups and the specific areas of surfactants on the surfaces of micelles. The Donnan equilibrium model was used to calculate the exchange of sodium and calcium and to make a comparison with mass-action models.
Pressure-Derivative Type Curves, for Vertically Fractured Wells
Authors: Tiab Djebbar , Puthigai Suresh K. 
Published: December 2007

Summary
This paper presents a technique for interpreting pressure-derivative type curves for a vertically fractured well located in an infinite reservoir. These type curves can be used to match pressure test data to determine the formation permeability, the half-length of the fracture, and the nature of the fracture—i.e., uniform-flux fracture or infinite-conductivity fracture. At long producing times, the buildup type curves are identical to the drawdown type curves for both types of fractures.
Performance of Finite-Conductivity, Vertically Fractured Wells in Single-Layer Reservoirs
Authors: Bennett Curtis O. , Reynolds Albert C. , Raghavan Rajagopal , Elbel Jacques L. 
Published: December 2007

Summary
Although even a perfunctory survey of the literature suggests that considerable information is available on the response of finite-conductivity fractures in single-layer systems, the influence of the settling of propping agents and the effect of fracture height on the well response need to be examined. These topics are examined in this paper. We suggest methods to analyze well performance when the fracture paper. We suggest methods to analyze well performance when the fracture conductivity is a function of fracture height and fracture length. The performance of wells with fracture height greater than the formation performance of wells with fracture height greater than the formation thickness is documented. The consequences of being unable to contain the fracture within the pay zone are also examined.
Although incidental to this study, we found that solutions presented by various authors are not in agreement for all time ranges. In this paper, we discuss a systematic procedure to obtain a grid (mesh) so that paper, we discuss a systematic procedure to obtain a grid (mesh) so that accurate results are obtained by a finite-difference model. This procedure can be used for both two-dimensional (2D) and three-dimensional (3D) problems. problems.
Application of a Regression-Based EOS PVT Program to Laboratory Data
Authors: Coats K. H. , Smart G. T. 
Published: December 2007

Summary
An equation-of-state (EOS)-based PVT program was applied to match laboratory PVT data for three published and nine additional reservoir fluid samples. This paper includes laboratory test data for the nine samples and describes PVT program features, especially regression, that we find conducive to rapid determination of EOS parameter values needed to match data. With regression, both the Peng-Robinson (PR) and Zudkevitch-Joffe-Redlich-Kwong (ZJRK) EOS give comparable and generally good agreement with laboratory data. Without regression or significant adjustment of EOS parameters, neither EOS adequately predicts observed reservoir fluid PVT behavior.
Our EOS tuning uses a small degree of C7 + fraction splitting. The agreement of these EOS results with data compares favorably with that obtained in previously published studies that used extensive C7+ splitting.
A Nonequilibrium Description of Alkaline Waterflooding
Authors: deZabala E. F. , Radke C. J. 
Published: December 2007

SummaryAlkaline waterflooding is complicated because the surfactant species are generated in situ from acidic components in the crude oil rather than injected externally. We previously outlined an equilibrium displacement theory1 that captured the essential features of the process. Assumption of local equilibrium, however, does not allow for a careful examination of the complex transport and kinetic phenomena that occur. Our non-equilibrium theory models the pertinent mass-transfer and kinetic resistances affecting interfacial tensions (IFT's) during displacement and oil-recovery efficiency. The model shows that when natural acid in a trapped oil blob contacts alkali, it diffuses to the interface, adsorbs, reacts with alkali, desorbs, and convects into the bulk aqueous phase. We quantify these transport steps, calculate concentration profiles in the oil and flowing aqueous phases during a linear displacement, and determine how transient tension behaves as a function of time and distance. Mass-transfer resistances are insignificant, but sorption resistances at the oil/water interface affect the transient evolution of IFT during alkaline displacement. Interfacial sorption barriers are modeled with first-order kinetics. Desorption resistances may be quite large, so low IFT's may not be established in typical laboratoryscale cores. Reversible or irreversible surfactant adsorption on reservoir rock is detrimental to alkaline waterflooding. Rock adsorption reduces the amount of surfactant available to the oil/water interface and may raise the IFT to levels that are ineffective in mobilizing residual oil globules. Most importantly, we provide a conceptual framework to design a successful alkaline waterflood.
A General Study of Asphaltene Flocculation Prediction at Field Conditions
Authors: Gharfeh Samir , Singh Probjot , Kraiwattanawong Kriangkrai , Blumer David 
Published: December 2007

Summary
A large set of field data have been collected during the last decade related to various facets of asphaltene instability problems at our production facilities. These problems include compatibility of heavy oil with hydrocarbon diluents in a Venezuelan operation, commingling of live oil and condensate in a North Sea production facility, compatibility of drilling mud-base oil, and miscible injectants with reservoir fluids in Alaskan operations. In each of the field cases, significant lab data were generated by titrating the neat dead crude oil, and oil-solvent blends with n-alkanes. The solvents used to study the asphaltene issue were toluene, condensate, and base oil. We have applied available asphaltene prediction techniques (Heithaus 1960, 1962; Wiehe and Kennedy 2000ab; Wiehe et al. 2001; Andersen 1999; Wang and Buckley 2001; Wang et al. 2003, 2004; Leontaritis 1998) to explain the field data. None of the models has been found comprehensive enough to explain flocculation at all the conditions, including the flocculation that occurs at ambient conditions in the presence of paraffinic diluents; stability enhancement that occurs upon addition of aromatic solvents; and the instability that occurs in a live fluid because of changes in composition, pressure, and temperature. To handle a complex crude oil system, these models made some simplifying assumptions that enabled them to make the problem manageable. In doing so, they lose some predictive capability. We found there are two forces that need to be accurately captured— dynamics of the alteration of solubility parameter of the hydrocarbon matrix, and change in entropy of mixing—to model the asphaltene behavior. The latter has been either empirically estimated by extrapolating the ambient titration data or neglected in many of the previous models. The basic parameters for our model can be calculated from lab data generated by titrating the dead crude oil, or oil solvent blends with n-alkanes, at different temperatures. So far, this model has been applied to various field conditions in production facilities and has been found successful in matching the field data.
Hydrate Remediation in Deepwater Gulf of Mexico Dry-Tree Wells: Lessons Learned
Authors: Harun A. F. , Krawietz T. E. , Erdogmus M. 
Published: December 2007

Summary
Hydrate plugs were formed above the mudline in two dry tree oil wells in the Gulf of Mexico. The plugs were formed when trying to open the downhole safety valve with crude to return the wells to production after they were shut-in because of hurricane evacuation. Several unsuccessful attempts to melt the hydrate blockages included pumping methanol through the chemical injection lines below the plugs and lubricating in glycol above the plugs. As a last attempt, before using coiled tubing, injecting hot oil into the tubing-casing annulus was considered. Transient simulations were performed to determine the required injection temperature, rate, and time. Well integrity issues were mainly associated with the compatibility of the hot oil with the elastomers and possible as-phaltene or paraffin precipitation in the annulus. Sensitivity studies show that with a 1-bbl/min injection rate and 150°F injection temperature, the pressure-temperature condition inside the tubing located 3,000 ft below the sea level will come out of the hydrate formation region within 4 hours. However, as the section goes deeper, the warm up time increases and at some point the conditions will not warrant being out of the hydrate region even after several days of injection time. Hydrate plugs in two dry tree wells melted after 6 and 60 hours of injection time, respectively. A revised restart procedure has been implemented to eliminate the hydrate problem in future startups.
Casing and Tubing Design Considerations for Deep Sour-Gas Wells
Authors: Stair M. A. , Mclnturff T. L. 
Published: December 2007

SummaryTubular metallurgy is usually considered to be the dominant design requirement associated with deep sour-gas wells and as such has received extensive treatment in the industry's literature. Other requirements vital to the assurance of a successful well design, however, have not been treated adequately in the literature. This paper addresses some of the nonmetallurgical requirements incorporated in our drilling operations in the deep, sour, geopressured areas south of Jackson, MS, and in the Tuscaloosa trend in Louisiana. The following topics are included: (1) the need and use of the maximum distortion strain energy—von Mises—technique for designing production tubulars; (2) a testing technique used to evaluate connections for use with these tubulars; (3) unusual design and operational features of these wells; and (4) the inspection and handling requirements to ensure the integrity of the wellbore tubular.
Determination of Gas-Condensate Relative Permeability on Whole Cores Under Reservoir Conditions
Authors: Gravier J. F. , Lemouzy P. , Barroux C. , Abed A. F. 
Published: December 2007

SummaryRock samples from a Middle East carbonate retrograde condensate gas field were studied to determine their relative permeability to gas and condensate curves. We have emphasized the determination of condensate minimum flowing saturation—or critical condensate saturation—and the reduction of permeability to gas in the presence of immobile condensate saturation.A ternary pseudoreservoir fluid of methane/pentane/nonane made it possible to work in simulated reservoir conditions with a greater flexibility for experimental procedures. The initial water saturation equaling that in the reservoir was restored. The results of the gas-condensate system indicate that the critical condensate saturations are high (the average value is 36% PV) and that the reduction of permeability to gas is higher than for a standard gas/oil system. Also presented are the details of the experimental procedures, the fluid characteristics, the results, and a discussion.
Streamtube Relative-Permeability Functions for Flashing Steam/Water Flow in Fractures
Authors: Gudmundsson J. S. , Menzies A. J. , Horne R. N. 
Published: December 2007

Summary
The flow of steam/water mixtures into geothermal wells is analyzed by use of a two-phase model for flashing flow. The model includes the effect of heat transfer from the formation rock to the two-phase mixture. In the reservoir/well system, the two-phase flashing flow is assumed to occur in fractures. The model can be used to forecast the mass flow and enthalpy characteristics of two-phase geothermal wells. Relative permeability functions are derived for flashing steam/water flow in the feed-zone fractures of geothermal wells.
Alcohol Extraction Technique for In-Situ Determination of Resident Water Saturation and Resident Brine Salinity
Authors: Mut A. D. , Deans H. A. 
Published: December 2007

Summary
Water saturation and formation water salinity traditionally have been difficult to determine in reservoirs that are at irreducible water saturation conditions. An approach to the problem has been developed in the form of a single-well, in-situ extraction technique that can determine both quantities simultaneously. A mathematical model describing the technique was written and subsequently used to predict the behavior of a series of laboratory experiments. The experiments were performed on Berea sandstone cores at a variety of water saturations and brine salinities. The predicted and observed production profiles are in excellent agreement.
Experimental Investigation of the Effects of Temperature, Pressure, and Crude Oil Composition on Interfacial Properties
Authors: Hjelmeland O. S. , Larrondo L. E. 
Published: December 2007

Summary
The wettability of the fluid/rock system affects the distribution of fluids within a porous medium; this distribution in turn strongly affects displacement behavior and oil recovery efficiency. This paper is an investigation of the influence of temperature, pressure, and oil composition on the wettability of a specific carbonate reservoir. Contact-angle measurements were used to quantify wettabilities on calcium-carbonate crystals. The experimental conditions included varying temperature and pressure for both dead crude oil and oil recombined to the original bubblepoint. In addition to quantification of wetting properties, interfacial tension (IFT) between oil and water was measured, and formation of rigid films was observed.
A complete reversal from a predominantly oil-wet system at lower temperatures to a predominantly water-wet system at higher temperatures was found. Pressure alone had little effect on the wettability of the system. IFT between crude oil and brine showed an increase with increase in temperature under anaerobic conditions, whereas at aerobic conditions, IFT decreased with increase in temperature. The tendency to form rigid films at the crude-oil/brine interface was found to be temperature-dependent. The formation of rigid films was stronger at lower temperatures.
Automatic History Matching of Laboratory Corefloods To Obtain Relative-Permeability Curves
Authors: Macmillan D. J. 
Published: December 2007

Summary
A standard automatic history-matching technique is applied to a Buckley-Leverett solution of laboratory corefloods to obtain oil/water relative-permeability curves. Several laboratory coreflooding examples are included to illustrate the usefulness of this method.
Bumper-Pile Design for Mating Platform and Subsea Drilling Template
Authors: Nelson W. E. , Murphy Benton S. , Stahl Bernhard 
Published: December 2007

Summary
This paper describes the procedures used to design bumper piles for the docking installation of a large North Sea platform jacket over a subsea drilling template. Model tests are described and their response data presented and interpreted for design use. Procedures are presented for evaluating ultimate load- and energy-absorbing capacities of the docking piles together with the jacket-bottom horizontal framing. Conclusions are drawn and observations offered concerning analytical methods for determining docking pile design loads and the feasibility of mating large platform assemblies offshore.
Displacement of a Viscous Oil by the Combined Injection of Hot Water and Chemical Additive
Authors: Karakas M. , Saneie S. , Yortsos Y. 
Published: December 2007

Summary
A model of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is presented. The process considered is one-dimensional (1D), two-phase flow, with negligible effects of dispersion, heat conduction, and lateral heat losses. The model allows for the chemical to be soluble in the aqueous phase and to be adsorbed on the solid surface. The effects of temperature on the viscosity ratio and the adsorption thermodynamics and of chemical concentration on the fractional flow curves are considered.
The theory of generalized simple waves (coherence) is used to develop solutions for the temperature, concentration, oil-saturation profiles, and oil-recovery curves. The results show that, in the adiabatic case, the combined injection of chemical and hot water enhances the oil recovery considerably. The sensitivity of the recovery performance to the process parameters is discussed. It is shown that, for Langmuir adsorption equilibrium, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value and in the unheated region if its concentration exceeds this critical value. Typical results for a chemical pulse injection in a tertiary recovery process indicate that the recovery performance is maximized when the chemical resides entirely in the heated region of the reservoir.
A Laboratory Investigation of Sweep During Oxygen and Air Fireflooding
Authors: Garon A. M. , Kumar M. , Lau K. K. , Sherman M. D. 
Published: December 2007

Summary
An experimental investigation of volumetric sweep during fireflooding was conducted in threedimensional (3D) scaled models. The effect of oxygen vs. air injection, water/oxygen ratios, injection rates, and crude-oil parameters on sweep efficiency and performance of the fireflood were evaluated. Results indicate that the sweep of a fireflood was similar for both oxygen and air combustion; water injection resulted in a small decrease in the sweep of the fireflood; wet combustion required less oxygen or air and increased the oil recovery and recovery rate; fireflooding a medium-gravity crude-oil reservoir resulted in a larger sweep than a heavy-oil reservoir; and (within the limited range of this study) higher injection rates improved the sweep efficiency.
Estimation of In-Situ Stresses From Ultrasonic Measurements
Authors: Mao N. H. , Sweeney J. J. 
Published: December 2007

Summary
The results of an effort to develop a technique for estimating in-situ stresses by measurement of stress-induced velocity anisotropy around a borehole are presented. Relevant parameters required to make the estimate were identified and measured in the laboratory on a 35.6-cm [14.0-in.] cube of Nugget sandstone with a 10.2-cm [4.0-in.]-diameter hole under biaxial loading. Two pairs each of radially and tangentially polarized transducers were placed inside the hole with displacement directions either parallel or perpendicular to the principal stress directions. With this configuration, relative travel times were measured by both a pulsed phase-locked loop (P2L2) technique and a cross correlation of digitized waveforms. The biaxial velocity data were used to back-calculate the applied stress. The standard deviation of the differences between the calculated and applied stresses is 0.62 MPa [90 psi] for a stress level up to 8.63 MPa [1,252 psi].
Magnus Subsea Wells: Design, Installation, and Early Operational Experience
Authors: Dawson A. P. , Murray M. V. 
Published: December 2007

Summary
This paper describes the subsea aspects of the Magnus field development. The design and installation of the well completions and control systems are described. Problems encountered during this phase and during the early production life of the system are discussed. Some of the longer-term operational aspects are also discussed, and recommendations are made to improve subsequent subsea developments.
The Geologic Aspects of Reservoir Characterization for Numerical Simulation: Mesaverde Meanderbelt Sandstone, Northwestern Colorado
Authors: Jones J. R. , Scott A. J. , Lake L. W. 
Published: December 2007

Summary
Major shortcomings in the geologic descriptions used in numerical simulations are addressed by a reservoir characterization of Mesaverde sandstone outcrops in northwestern Colorado. A geologic model for Mesaverde point-bar deposits using core plug data relates permeability trends to stratification type. This reservoir characterization helps develop a general reservoir descriptor that analyzes actual field permeability data that are related to an observable feature (stratification type).
Rock-Property Changes During Reservoir Compaction
Authors: Morlta Nobuo , Gray K. E. , Srouji Farlz A. A. , Jogl P. N. 
Published: December 2007

Summary
Deformations, absolute permeability, electrical resistivity, PV change, and compressional- and shear-wave velocities were measured for Berea sandstone under various loading paths at temperatures from 70 to 380°F. The experimental behavior was subdivided into five categories. The experimental results were analyzed for each category, and the analysis was used to construct semianalytical rock-propery equations. These equations accurately simulate complex rock properties under various loading paths, which, unlike conventional rock-property equations, are expressed in terms of strain components. This formalism is practical because strains are more directly related to rock properties than are stress components. This paper presents unique rock-property data, including axial and radial measurements with various loading paths and temperatures; semianalytical equations that accurately simulate rock properties under various loading paths up to rock failure; and realistic predictions of rock-property changes during reservoir compaction.
Triple-Fluid Evaluations Using Density, Neutron, and Electromagnetic Propagation Logs
Authors: Peeters M. 
Published: December 2007

SummaryDetermining the remaining oil, gas, and water saturations simultaneously, independent of water salinity, is often necessary for EOR. The triple-fluid method determines these saturations quantitatively using the apparent porosities of the electromagnetic propagation tool (EPT), density, and neutron logs.Field examples are compared with service-company products to demonstrate that neutron-log shale corrections are mandatory. Dielectric logging tools with larger investigation depth are required to make the method generally applicable.
A New Technique for Visualizing the Distribution of Oil, Water, and Quartz Grains in a Transparent, Three-Dimensional, Porous Medium
Authors: Chen Jing-Den , Wada N. 
Published: December 2007

Summary
A new technique for visualizing the distribution and structure of oil, water, and quartz particles in a transparent, three-dimensional (3D), porous medium is presented. A laser light sheet illuminates a slice of a rectangular cell containing a mixture of oil, water, and quartz particles. All three phases have the same refractive index. The quartz particles do not fluoresce. From the different fluorescence colors of water and oil, the cross-sectional distribution of the three phases can be visualized. Photographs of different cross sections are presented that show both the solid grain structure and trapped oil blobs. This technique can be used to study two-phase flow in porous media.