bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elevated-Temperature Caustic/Sandstone Interaction: Implications for Improving Oil Recovery
Authors: Sydansk Robert D. 
Published: December 2007

Abstract
Caustic in the form of sodium hydroxide solutions is shown to interact strongly with sandstone at elevated temperature (185°F). Such interaction has substantial influence on the success of secondary and tertiary oil-recovery sodium hydroxide floods carried out in sandstone formations of more ordinary temperatures.
Caustic in the form of sodium hydroxide interacts with sandstone at elevated temperature to promote (1) significant dissolution of the more susceptible silicate minerals, predominantly clay and large-surface-area silica minerals; (2) sandstone weight loss; (3) increased porosity; (4) propagation of significant concentrations of water-soluble silicates, including sodium orthosilicate; (5) in-situ formation of new immobile aluminosilicate material; (6) changes in permeability; and (7) hydroxide ion consumption.
Caustic/sandstone interaction resulting from sodium hydroxide dissolution of silicate minerals is limited by kinetics. The interaction increases with increasing temperature, increasing sodium hydroxide concentration, and increasing caustic/sandstone contact time. The rate and the amount of interaction are sensitive to sandstone mineralogy and lithology. Although not studied during this work, the presence of crude oil, along with crude-oil type, may affect the rate and the amount of interaction.
Based on the laboratory study of elevated temperature caustic/sandstone interaction involving silicate-mineral dissolution by sodium hydroxide, it is concluded that, at lower temperatures, the much slower dissolution interaction has implications for field application of sodium hydroxide for improving waterflood sweep efficiency and enhancing oil recovery. Specifically, during field applications, the slow interaction could deplete the active hydroxide ions. More common low-temperature field applications are especially susceptible because of long caustic/sandstone contact times and because, in general, relatively small concentrations of sodium hydroxide have been used historically. This study points out that proper extrapolation of laboratory caustic-flooding results to field conditions should account for slow kinetic phenomena. The study also helps explain detrimental caustic/sandstone interactions and lower-than-expected oil recoveries experienced during a number of long-duration low-temperature enhanced oil recovery (EOR) field tests and floods.
On the positive side, the dissolution interaction, especially at elevated temperatures, generates in-situ significant concentrations of water-soluble silicates, including sodium orthosilicate. Water-soluble silicates have been reported as candidates for improving oil recovery and for use in preflushes to condition formations for other EOR techniques. Other than noting their in-situ formation and propagation, we did not study the alkaline water-soluble silicates in detail, and they are not discussed.
Laboratory Investigation on the Effect of In-Situ Stresses on Hydraulic Fracture Containment
Authors: Warpinski Norman R. , Clark James A. , Schmidt Richard A. , Huddle Clarence W. 
Published: December 2007

Abstract
Laboratory experiments have been conducted to determine the effect of in-situ stress variations on hydraulic fracture containment. Fractures were initiated in layered rock samples with prescribed stress variations, and fracture growth characteristics were determined as a function of stress levels. Stress contrasts of 300 to 400 psi (2 to 3 MPa) were found sufficient to restrict fracture growth in laboratory samples of Nevada tuff and Tennessee and Nugget sandstones. The required stress level was found not to depend on mechanical rock properties. However, permeability and the resultant pore pressure effects were important. Tests conducted at bimaterial interfaces between Nugget and Tennessee sandstones show that the resultant stresses set up near the interface because of the applied overburden stress affect the fracture behavior in the same way as the applied confining stresses. These results provide a guideline for determining the in-situ stress contrast necessary to contain a fracture in a field treatment.
Automatic Log Computation at Wellsite-Formation Analysis Logs
Authors: Tixier M.P. , Eaton F.M. , Tanguy D.R. , Biggs W.P. 
Published: December 2007

Abstract
New logs and greater flexibility in electrical well logging applications are now provided by truck-mounted computer systems. These special computers digitize and record on tape the data from well surveys. Simultaneously with the recording of a subsequent log, the computers merge taped data and perform continuous log analysis computation. The optical recordings of these computations provide a rapid means of formation evaluation in the field. Two computer systems have been developed. In one the data are recorded digitally on punched paper tape. The second system records the data digitally on magnetic tape using a format compatible with most digital computers. A major application of the truck-mounted computers systems has been the merging of data from an induction-electrical survey with that from either a sonic or a formation density log. The resulting formation analysis log consists of continuous curves of Rwa, Fr/Fs (or Fr/Fd), and apparent porosity. The location of potential pay zones is more easily and quickly accomplished by scanning these computed logs than by manually performing the many computations required for a similar study. Since computations are automatically performed on all zones, it is unlikely that productive zones will be overlooked. Other combinations of log data are also possible.
Introduction
Several years ago a method was proposed by Tixier, et al., in which simple computations of data from resistivity and sonic logs provide more reliable "quick look" interpretations. These techniques, which involve the manual computation of an apparent water resistivity Rwa and of an Fr/Fs ratio, have been widely used by the industry. The methods use the sonic data to normalize formation resistivities for variations in porosity and shaliness. In the application of the techniques, Rwa and Fr/Fs values are computed and tabulated for many levels. Computations are made not only for zones of apparent interest on the resistivity curves, but also for obvious water-saturated intervals and shaly sections. The tabulated results or, even better, semi-continuous plots, as shown in Fig. 1, focus attention on the zones of interest. Oil- or gas-bearing intervals are indicated by Rwa and Fr/Fs values significantly higher than obtained for water-saturated zones. The log analyst may then concentrate his attention on the formations that offer production possibilities. He can selectively use his more complete and more precise methods of interpretation and, thus, perform the necessary evaluations in the shortest time. These quick look methods are particularly beneficial at the wellsite.
JPT
P. 22ˆ
Experimental Determination of Solids Fraction and Minimum Volumetric Requirements in Air and Gas Drilling
Authors: Machado Carlos J. , Ikoku Chi U. 
Published: December 2007

Abstract
There are so many variables involved in air or gas drilling that one general correlation has not been developed to predict appropriate volumetric requirements in the field. The results of previous attempts to calculate minimum volumetric requirements are valid over limited ranges of drilling conditions.
This research has developed new empirical correlations for solids friction factor for sandstone, limestone, and shale. A new and more realistic technique for predicting minimum volumetric requirements is presented. This method includes a complete analysis of pressures throughout the system. It also offers flexibility in the selection of standpipe pressure, air flow rate, and, thus, compressor specification. The method is primarily graphical, so it can be used at the well site without access to a computer.
Our results confirm that existing methods may predict a volumetric flow rate too low or too high.

Introduction
In the late 1940's, air or gas drilling began, which can be defined as a technique that utilizes air or gas as the circulating medium. However, the injection of compressed air as a circulating medium has been in common use since the late 1800's.
Air (gas) is the ultimate low-density drilling fluid. Optimal results and greatest economy from air or gas drilling depend on several factors. Hard formations that are dry or produce relatively few formation liquids provide the best results. In air and gas drilling, the particles transported in the annular flow stream are of various sizes, shapes, and densities; therefore, each particle has a different terminal velocity in a determined medium. The particles are disintegrated during removal by the turbulent flow in the annulus and the grinding action of the drill stream; thus, the distribution of particle sizes varies at different levels in the annulus.
Equations governing the settling of rock particles and volume requirements for air drilling have been given by many researchers. The important relationship between the control of fluid properties and adequate hole cleaning was addressed first by Piggot in 1941. He applied modified forms of Stokes' law for viscous flow and Rittinger's formula for turbulent flow to predict terminal settling velocity.
JPT
P. 2645^
A Proposed Model for Multiphase Flow Through Naturally Fractured Reservoirs
Authors: Evans Ronald D. 
Published: December 2007

Abstract
A general mathematical model is derived that may be used to describe fluid movement through naturally fractured reservoirs. The model treats the reservoir as a double-porosity medium consisting of heterogeneous, isotropic primary rock matrix blocks and an anisotropic, heterogeneous fracture matrix system. The fractures are assumed to have a general distribution in space and orientation called the fracture matrix function to represent their statistical nature. Simplifying assumptions are made concerning flow in individual fractures, and a hemispherical volume integration of microscopic fracture flow equations is performed to arrive at a generalized Darcy-type equation, with a symmetric permeability tensor evolving to describe the flow in the fracture matrix. For flow in the primary rock matrix blocks, Darcy's law for an isotropic medium is assumed.
Time-dependent porosity equations for the primary rock matrix and the fractures are derived and coupled with the conservation of mass principle for each system to arrive at a governing set of continuity equations. Each resulting continuity equation is coupled further by a fluid interaction term that accounts for fluid movement that can take place between rock matrix blocks and fractures. The resulting equations of continuity and the equations of motion are generalized for multiphase flow through the fractured medium with variable rock and fluid properties. To complete the model formulation, a general set of auxiliary equations are specified, which can be simplified to fit a particular application.
An Oscillating Backpressure Regulator for Low Flow Rate, High-Pressure Coreflooding Experiments
Authors: Lease W. O. , Van Egmond C. F. 
Published: December 2007

Summary
An oscillating back pressure regulator (OBPR) has been developed that is capable of accurately controlling backpressures as high as 6,000 psi at flow rates ranging from approximately 1 to 100 mL/hr. It has been applied successfully in CO2/crude oil coreflooding experiments involving the simultaneous flow of three fluid phases. The device is assembled easily from off-the-shelf components.
Steamflooding
Authors: Matthews C.S. 
Published: December 2007

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering.

Introduction
Steamflooding has become an established recovery technique within the last20 years. This overview discusses its evolution, methods for selecting and designing steamfloods, constraints, and possible improvements. The term steamflooding is used here in a general sense. The discussion includes steamsoak (cyclic steam injection) and steam drive. For additional information the reader should refer to Farouq Ali and Meldau.

Early Developments: Steam Soak
There are records of steam injection into a Texas oil reservoir as far back as 1931. Steam drive on a sustained basis, however, did not begin until 1959–60 when Shell affiliates undertook steamflood pilots in Schoonebeek, the Netherlands, Mene Grande, Venezuela, and Yorba Linda, CA. Steaming operationsstill under way at Schoonebeek and Yorba Linda are discussed later.
Venezuela. The steamdrive pilot in Mene Grande led to development of the steamsoak process. While attempting to relieve the formation pressure by opening a steam injector to production, oil was produced surprisingly at a rate of 100 to 200 B/D. produced surprisingly at a rate of 100 to 200 B/D. This was the first steamsoak well. This process underwent considerable development in both
Venezuela and the U.S. Most of the oil produced by steam from 1960 to 1970was by this process. Typically, steam is injected for several weeks and then the well is closed in (soaked) until the steam has condensed, A pump then is run and the well is placed on production. When oil production falls to a lowlevel, the cycle is repeated. Thermal production in Venezuela is still almost entirely (95%) from steam soak. Compaction of these thick, unconsolidated sands together with solution-gas drive is leading to satisfactory oil recovery atvery high ratios of oil recovered per barrel of steam used.
The Netherlands. One of the first large-scale steam drives began at the Schoonebeek field in The Netherlands in 1960. Recovery of the moderately viscous oil (180 cp) was quite successful. This encouraged additional fieldtrials of steam drive in the U.S. and in Venezuela. Coring showed that steamwas achieving low residual oil saturations of the order of 8%. The residual oilin the zone swept only by hot water was about 35%. Later tests at Schoonebeek were carried out at high pressure and high temperature. Under these conditionsCO2 and H2S are generated in situ. Consequently, new alloys had to bedeveloped. Thus, Schoonebeek led to pioneering along both reservoir andmetallurgical lines.
U.S. Commercial steamflooding began in the U.S. in 1960 in the Yorba Lindafield, CA.
JPT
p. 237
Genome size microscale divergence of Cyclamen persicum in Evolution Canyon, Israel
Authors: Pavlíček Tomáš , Bureš Petr , Horová Lucie , Raskina Olga , Nevo Eviatar 
Published: December 2007

Abstract
Using DAPI flow cytometry, we examined genome size divergence of the Persian violet, Cyclamen persicum (Primulaceae) (2n=48) on close opposite slopes of Evolution Canyon (EC), Mt. Carmel, Israel. The range of genome size variation detected among measured cyclamens was 6.41% in relation to the smallest measured DNA content. Our data on C. persicum at EC showed that local variability in the 2C-value exists. Significantly less DNA was recorded in plants growing in one station of the African savannah-like south-facing slope (AS) but not in the remaining two stations of the same slope. We were not able to reject the null hypothesis that there are no significant interslope differences in the genome size between the temperate European garrigue-like north-facing slope (ES) and the drier AS. In spite of the nonsignificant interslope trend for the higher genome size in C. persicum, the data-fusion (meta-analysis) test using correlations between C-values in C. persicum, and earlier studied carob tree (Ceratonia siliqua), trifoil (Lotus peregrinus) and a beetle (Oryzaephilus surinamensis) and their distribution along the aridity gradient indicates a positive relationship between drought and genome size at the microsite.
Coronary angiography and dual-source computed tomography are complementary methods in diagnosis of significant stenosis of the right coronary artery originating from the left aortic sinus
Authors: Veselka Josef , Zemánek David , Duchoňová Radka , Blaško Peter , Adla Theodor , Tesař David , Neuwirth Jiří 
Published: December 2007

Abstract
Anomalous origin of the right coronary artery from the contralateral aortic sinus is a rare but potentially fatal congenital abnormality. We analyzed 8.066 consecutive coronary angiograms and found 4 cases demonstrating this anomaly. In 2 cases the right coronary artery was without significant atherosclerotic lesions and coursed between the aorta and pulmonary trunk. In the 2 other cases the right coronary artery was significantly stenosed. In the last case, diagnosis was based on angiographic and dual-source computed tomographic examinations. Dual-source computed tomography showed precisely the origin and course of the right coronary artery between the ascending aorta and pulmonary artery. Moreover, stenoses of the anomalous coronary artery were depicted. Subsequent coronary interventions required modification of the Amplatz left guiding catheter, which enabled a sufficient support even for coronary artery stenting. Both methods seem to be complementary in the diagnostic and therapeutic process of this coronary anomaly.
Successful discontinuation of insulin treatment after gestational diabetes is shown to be a case of MODY due to a glucokinase mutation
Authors: Talapatra Indrajit , Kalavalapalli Shyam , Robinson Jonathan , Ellard Sian , Tymms David 
Published: December 2007

AbstractWe describe a woman who first presented with gestational diabetes at 26 weeks gestation and was managed with insulin. Following delivery of a healthy baby she had an abnormal OGTT (oral glucose tolerance test) 6 weeks post partum and was managed with diet. In her second pregnancy she was diagnosed with gestational diabetes at 10 weeks and required insulin. Following delivery she was again managed on diet alone. Four years later, during her third pregnancy, she was managed with insulin from the outset. She remained on insulin post partum and for several years. Later her two younger children, aged 11 years and 7 years, were found to have GCK mutation causing MODY (Maturity Onset Diabetes Of the Young) subtype glucokinase. Following this she underwent molecular genetic testing and was also shown to have the GCK mutation. She was gradually taken off insulin and is now managed on diet alone with excellent glycaemic control. Her two children are under regular follow up care and on no medication for diabetes.
Technology and characterisation of GaAsN/GaAs heterostructures for photodetector applications
Authors: Ściana B. , Zborowska-Lindert I. , Pucicki D. , Boratyński B. , Radziewicz D. , Tłaczała M. , Serafińczuk J. , Poloczek P. , Sęk G. , Misiewicz J. 
Published: December 2007

AbstractThe nitrogen-containing conventional AIIIBV semiconductor alloys, so-called diluted nitrides (AIIIBV-N), have been extensively studied recently. Unusual properties of these materials make them very promising for applications in lasers and very efficient multijunction solar cells. This work presents the technology and properties of undoped GaAs1-xNx/GaAs heterostructures used as active regions in the construction of metal-semiconductor-metal (MSM) photodetectors. The atmospheric pressure metal organic vapour phase epitaxy (APMOVPE) was applied for growing MSM test structures. Their structural and optical properties were examined using high resolution X-ray diffraction (HRXRD), photoluminescence (PL), and photoreflectance spectroscopy (PR). Chemical wet etching was applied for forming an active region and a multifinger Schottky metallization was used as MSM contacts. Dark and illuminated current-voltage characteristics were measured. Based on the obtained results, the main detector parameters as responsivity and spectral response were estimated
Temperature dependence of linear electrooptic coefficients r 113 and r 333 in lithium niobate
Authors: Górski P. , Ledzion R. , Bondarczuk K. , Kucharczyk W. 
Published: December 2007

AbstractA new method of determination of individual linear electrooptic coefficients is proposed. The technique is based on the dynamic polarimetric measurements and takes into consideration the temperature dependences of ordinary and extraordinary refractive indices. Results obtained for the electrooptic coefficients r113 and r333 in LiNbO3 are presented. The coefficients are found to increase significantly within the considered temperature range 25-200°C. The temperature dependences of the intrinsic coefficients m113 and m333, defined in terms of the induced polarisation, are considered as well.
Analysis of quadratic electrooptic response of BaTiO3 crystal in ferroelectric phase
Authors: Izdebski M. , Kucharczyk W. 
Published: December 2007

AbstractUsing the example of BaTiO3 in a ferroelectric phase it is shown that a large difference in magnitudes of individual linear electrooptic coefficients may be a reason of additional indirect quadratic contributions that are independent of real quadratic coefficients. For some directions of the applied field and light, the indirect contributions may be even larger than the real quadratic ones. Independently of nonlinear distortions that can affect applicability of technical devices, a large difference between linear electrooptic coefficients may lead to serious problems in measurements of the real quadratic electrooptic effect. The analysis is based on the extended Jones matrix calculus applied to a Gaussian beam.
Density‐functional Theory of Magnetism
Authors: Bihlmayer Gustav 
Published: December 2007

AbstractThis chapter gives an outline of density‐functional theory (DFT) and its applications in the field of magnetism in the solid state. The basics of non‐spin‐polarized DFT and vector‐spin DFT are presented. Successes and limitations of different approximations to the exchange‐correlation functional, in particular the local‐density approximation (LDA), or the generalized gradient approximation (GGA) are discussed. The main focus in this chapter is on spin magnetism, but orbital magnetism and relativistic effects (magnetocrystalline anisotropy) are briefly introduced. Several methods, that can improve the description of localized states, for example, the self‐interaction correction or the LDA+Umethod are presented, as well as the orbital polarization (OP) technique, which can improve the underestimation of orbital moments in LDA or GGA. The relation to other theoretical methods, that is,GWor the dynamical mean‐field theory (DMFT), is indicated. Special techniques, like adiabatic spin dynamics, constrained local moment calculations and the treatment of incommensurate spiral spin‐density waves are presented. They can be used to determine the magnetic ground state or to extract exchange interaction constants from density‐functional calculations. Applications, for example, the calculation of the spin stiffness or the Curie temperature finally illustrate the predictive power of the theory.