bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fracture Dimensions in Frac&pack Stimulation
Authors: Fan Yong , Economides M. J. 
Published: December 2007

Abstract
A model is introduced to predict dynamic fracture dimensions in frac&pack stimulation. Design aspects of the two-in-one step treatment techniques, required by soft and high-permeability reservoirs are discussed. A pressure-dependent leakoff model, based on the transient flow of a non-Newtonian fluid displacing a reservoir fluid has been developed and incorporated with fracture mechanics concepts to simulate the entire process of frac&pack treatments including fracture propagation, inflation, proppant packing, and closure. Results obtained in this study indicate the considerable difference between traditional fracturing and frac&pack treatments. In the latter, fracture length is much less important than fracture conductivity. This work shows how to terminate the fracture growth at the appropriate time, and how to design frac&packs resulting in fracture widths several times larger than those for traditional fracturing.
Computing Pressure Distributions in Wedges
Authors: Chen Chih-Cheng , Raghavan Rajagopal 
Published: December 2007

Abstract
Pressure distributions for wells in wedge-type systems are derived in terms of the Laplace transformation Characteristics of responses are discussed and computational issues are addressed. The algorithm given here is a practical tool for analyzing flows in wedge-type systems and may be incorporated immediately into existing software packages. Existing solutions, in the petroleum-engineering literature, for pressure distributions in wedges are a subset of the solution given here.
Measurement of Aperture and Multiphase Flow in Fractures With NMR Imaging
Authors: Kumar Arun T. A. , Majors Paul , Rossen William 
Published: December 2007

Summary
Nuclear magnetic resonance imaging (NMRI) techniques were used for the measurement of the spatial distribution of apertures and two-phase fluid distributions in rock fractures. Rock models of known apertures were used to validate the NMRI technique. NMRI aperture values were in good agreement with nominal and hydraulic aperture values. The fracture signal in porous rock was isolated by NMR spin-spin relaxation times. Areal distributions of oil and water in an immiscible fracture flow were resolved on the basis of their NMR spin-lattice relaxation times.
Radiotracers in Gas-Liquid Transportation Problems-A Field Case
Authors: McLeod W.R. , Rhodes D.F. , Day J.J. 
Published: December 2007

Presented here are the results of a field program to develop and Presented here are the results of a field program to develop and evaluate radiotracer techniques for simultaneously measuring linear velocities of the individual phases of a multiphase stream. The flow properties monitored were used to compare experimental two-phase pressure drops with values predicted by techniques currently used pressure drops with values predicted by techniques currently used in design work.

Introduction
Numerous studies have been published on the transportation of gas-liquid mixtures through pipelines. However, the range of applicability pipelines. However, the range of applicability of most of the methods suggested for describing two-phase flow is generally limited to the conditions under which the investigations were performed. This shortcoming can be attributed performed. This shortcoming can be attributed either to improper design and instrumentation of the experiments or to departure of the analytic models, upon which the correlations are based, from the physical model or both. Therefore, further research in two-phase flow is needed to obtain more meaningful data for the solution of gas-liquid transportation problems.
A prerequisite to understanding two-phase flow in a pipe is an adequate knowledge of the interrelationship between the velocities of the individual phases, individual densities, the gas volume fraction and the gas weight fraction. It is very difficult, however, to measure the relative velocities of the individual phases. In addition, the method most commonly used in the past to obtain the vapor volume fraction was very unsatisfactory. It constituted isolating a portion of the pipe by means of quick-closing valves, and subsequently measuring the actual quantity of liquid present. The volume fraction of vapor obtained in this manner was an average value over the length of the test section, so the effect of geometrical changes on density of the two-phase mixture could not be accurately determined. These are serious shortcomings of previous investigations of two-phase flow.
In recent years a technique that has become more common for measuring fluid flow involves the use of radioactivity. This technique now offers easy and accurate means of measuring the linear velocity of each individual phase (radioactive tracer survey), and both the density and void fraction (gamma-ray attenuation). The method reported here to determine linear phase velocities is the Isotope Velocity method; a slug of radioactive material is injected rapidly into the flowing stream, and the transit time of the radionuclide between positions of known detector separation is measured. The accuracy of such a flow measurement depends upon the strength of the gamma rays emitted by the chosen isotope, accurate knowledge of the internal dimensions of the pipe, detector sensitivity and velocity profile.
JPT
P. 939
A Study of Displacements in Microscopic Capillaries
Authors: Templeton Charles C. 
Published: December 2007

Abstract
Any explanation of the nature of multiphase fluid flow through porous media must ultimately involve a knowledge of the mechanism of such flow through the individual pores of the medium. To provide quantitative information of the latter type, a study was made of gas-liquid and liquid-liquid displacements in single uniform Pyrex capillaries with diameters as small as 4 microns.
Quantitative observation of air-liquid displacements with zero contact angle indicates the adequacy of a model based on Poiseuille's Law and the independence of capillary pressure and interfacial velocity. Consequently, this work discounts previous claims that flow is abnormally retarded in very small capillaries.
For the displacement of a very viscous oil by water in a capillary initially filled with water, flow is faster than predicted by the above model. This behavior is probably due to the existence of a thin annular film of water between, the oil column and the capillary wall as postulated by Yuster.

Introduction
The need for experimental observation of the microscopic nature of multiphase fluid flow, to further the understanding of the results of macroscopic flow investigations, has been previously recognized. Chatenever and Calhoun in connection with the API Project 47B have extensively studied the flow of fluids through layers of glass or lucite spheres between glass or lucite plates.
Lowman prepared an interesting film concerning flow in a single capillary, using an apparatus which made a moving interface appear stationary in the field of a microscope.
The purpose of the present investigation was to determine what contribution might be made to this field by comprehensive quantitative observation of gas-liquid and liquid-liquid displacements in single capillaries of uniform, very small diameter. The techniques used are similar to those of Lowman but incorporate improvements necessary for quantitative work. Quantitative observations must begin with fluids of simple chemical composition to provide a basis for analyzing the more complex behavior that may be expected with natural reservoir fluids. However, some qualitative observations on systems involving crude oils are presented.
Low Surfactant Concentration Enhanced Waterflooding
Authors: Wellington Scott L. , Richardson Edwin A. 
Published: December 2007

Abstract
A new gradient scaled flooding test procedure indicated that oil is mobilized by the leading edge of the surfactant dispersion curve where the concentration is low, 1 to 10 ppm. Underoptimum, highly interfacially active blends of anionic and cationic surfactants were formulated to take advantage of the displacement mechanism. Essentially all the initial or residual crude oil was removed from shaly sand packs using approximately 0.4 percent surfactant with less than 0.1 pore volume loss.
Thermally Induced Fractures: A Field-Proven Analytical Model
Authors: Detienne J-L. , Creusot Max , Kessler Nicolas , Sahuquet Bernard , Bergerot J-L. 
Published: December 2007

Summary
Thermally induced fracturing (TIF) during water injection is a well-established phenomenon. TIF modeling implies solving equations simultaneously that conventional petroleum engineering applications deal with separately. Combining these equations leads to very complex computer programs. This has led to the need for a simple model, which we present in this paper. Coupling analytical expressions representing each of these phenomena, rather than the basic physical equations, has led to a computer program that can be run on a modern desk-top computer. This program has successfully matched the daily wellhead pressure and injection rate during a period of 3 to 5 years for injection wells in complex sandstone/dolomite reservoirs. The model can be used for injection-well monitoring as well as in a predictive mode when planning new water-injection projects. The algorithm is sufficiently simple to be implemented in a conventional reservoir simulator.
Recovery of Gas Condensate by Nitrogen Injection Compared With Methane Injection
Authors: Sänger Peter , Hagoort Jacques 
Published: December 2007

Summary
Methane injection or gas cycling is the recovery process of choice for gas-condensate reservoirs. For economic reasons, however, this process can often not be implemented. An alternative injection gas may be nitrogen, which is relatively cheap and available everywhere. Nitrogen, however, causes stronger liquid drop-out in the mixing zone between the gas condensate and the injected gas, which could reduce recovery.
This paper presents the results of slim-tube experiments and numerical simulations of the displacement of a model gas condensate at reservoir conditions by both nitrogen and methane. The gas condensate used is a three-component hydrocarbon system representative of a North Sea reservoir. The phase behavior and physical properties of mixtures of the gas condensate and injection gas were calculated with an equation of state tuned by some selected pressure/volume/temperature (PVT) experiments.
The main conclusion of this study is that the displacement of gas condensate by both nitrogen and methane is a developed miscible process, which results in high condensate recoveries. The recovery is adversely affected by dispersion; nitrogen is more sensitive to this than methane.
Theoretical Aspects of Emulsification in Porous Media
Authors: Raghavan R. , Marsden S.S. 
Published: December 2007

Abstract
A theoretical analysis of the mechanism of emulsification in porous media is presented. As an initial step in the investigation of the dispersion of one liquid in another, the hydrodynamic stability of a liquid layer surrounded by two other liquids is studied by the application of perturbation methods. Criteria for the hydrodynamic stability of the liquid layer are developed and the critical condition at which the instability occurs is predicted. Any disturbance of the interface is amplified, and, finally, jets of one liquid shoot out into the other phase. The radius of the droplets, as well as the phase. The radius of the droplets, as well as the number of droplets, formed are then determined.
The analysis presented pays due care to the viscometric aspects of the dispersion of one fluid into another. The mechanism oil emulsification proposed is based on the hypothesis that viscosity proposed is based on the hypothesis that viscosity differences between displaced and displacing liquids can lead to emulsion formation.

Introduction
A considerable amount of the world's crude oil is produced in the form of stable emulsions. These produced in the form of stable emulsions. These must be broken down into their two constituents, crude oil and brine, before sale and transportation of the former and disposal of the latter. The application of new recovery methods such as thermal simulation and surfactant flooding has, in many cases, accentuated the problem of emulsion formation. This, together with the introduction of new recovery methods using emulsions or emulsion floods, has led to considerable interest in both the generation and the flow of emulsions. Since there is sound evidence that emulsions are generated in some instances while liquids are flowing in porous media, we have investigated some of the viscometric aspects of emulsification by considering the hydrodynamic stability of liquid-liquid interfaces in porous media. porous media.
The Statfjord Satellites: Challenges and Experiences During Development and Production Startup
Authors: Malmin P. C. 
Published: December 2007

Summary
Production from the Statfjord Øst field was started up as planned and the project was completed within the overall budget. This paper reviews the handling of the more significant problems that were encountered during the development phase and gives a summary of the initial experiences after production startup.
After a description of the Statfjord satellite fields, the paper gives a résumé of the major tasks encountered during the development of these fields. The extensive modifications to the Statfjord C platform required by this project were performed while the platform was producing at its maximum capacity. Manning level and control of hot-work were two major issues in this context. In addition, the project team was able to add the necessary subsea equipment to ensure timely startup of gas production at Sleipner to the scope of the project. Two areas of environmental concern are described: (1) the reduction of flaring during well testing and (2) the containment of CO2 emissions as power consumption on the platform was increased.
Production from the two fields started in September 1994 and January 1995, respectively. After an initial running-in phase of a few weeks, production was very stable. The final challenge to overcome to start production was the need to get an agreement to reduce the continuous high production at Statfjord C to provide processing capacity for the Statfjord satellites.
Prediction of Gas Hydrate Formation Conditions in Aqueous Solutions of Single and Mixed Electrolytes
Authors: Zuo You-Xiang , Stenby Erling H. 
Published: December 2007

Abstract
In this paper, the extended Patel-Teja equation of state1 was modified to describe non-ideality of the liquid phase containing water and electrolytes accurately. The modified Patel-Teja equation of state (MPT EOS) was utilized to develop a predictive method for gas hydrate equilibria. The new method employs the Barkan and Sheinin hydrate model2 for the description of the hydrate phase, the original Patel-Teja equation of state3 for the vapor phase fugacities, and the MPT EOS (instead of the activity coefficient model) for the activity of water in the aqueous phase. The new method has successfully predicted the gas hydrate formation conditions in aqueous solutions of single and mixed electrolytes. The agreement between experimental data and predictions was found to be excellent.
A Contribution to Electrical Log Interpretation in Shaly Sands
Authors: Poupon A. , Loy M.E. , Tixier M.P. 
Published: December 2007

Abstract
Simple qualitative methods are explained for identifying those shaly sands in a well that are most likely to contain oil. A need for more precise measurement of the variables that enter shaly sand analysis is indicated. Field examples are given to illustrate the methods.
A theoretical discussion of the quantitative interpretation of shaly sands is given as a basis for discussion and as a guide for the future. While not generally capable of practical application at the present time because of the lack of sufficient accuracy of the electric log data, these methods may become more feasible in the future as the result of the improved logging methods now being introduced.

Introduction
Experience has shown that for porous formations containing only a negligible amount of clayey material, reliable information on the fluid saturation and porosity of the reservoir rocks can usually be derived from the electrical logs. The interpretation is based on empirical formulae relating the true resistivity of a porous formation to its lithologic character, to the resistivity of the interstitial water, and to the proportions of water and hydrocarbons in the pores. If the resistivity of the interstitial water is not known, its approximate value can be derived from the SP curve. The porosity can usually be determined to a good approximation from a MicroLog, or a MicroLaterolog.
When the reservoir rocks contain an appreciable percentage of clayey material, an additional factor is introduced into the analysis. In a clean formation, the matrix is an electrical insulator, so that the ability of the formation to conduct current is due only to the conductivity of the electrolytes in the pores; in a shaly formation, the shale constitutes a part of the rock matrix able to conduct current, and influences the resistivity of the formation.
Use of the Finite-Element Method in the Solution of Diffusion-Convection Equations
Authors: Shum Y.M. 
Published: December 2007

Abstract
A variational principle can be applied to the transient heat conduction equation with heat-flux boundary conditions. The finite-element method is employed to reduce the continuous spatial solution into a finite number of time-dependent unknowns. From previous work, it was demonstrated that the method can readily be applied to solve problems involving either linear or nonlinear boundary conditions, or both. In this paper, with a slight modification of the solution technique, the finite-element method is shown to be applicable to diffusion-convection equations. Consideration is given to a one-dimensional transport problem with dispersion in porous media. Results using the finite-element method are compared with several standard finite-difference numerical solutions. The finite-element method is shown to yield satisfactory solutions.

Introduction
The problem of finding suitable numerical approximations for equations describing the transport of heat (or mass) by conduction (or diffusion) and convection simultaneously has been of interest for some time. Equations of this type, which will be called diffusion-convection equations, arise in describing many diverse physical processes. Of particular interest to petroleum engineers is the classical equation describing the process by which one miscible fluid displaces another in a one-dimensional porous medium. Many authors have presented numerical solutions to this rather simple presented numerical solutions to this rather simple diffusion-convection problem using standard finite-difference methods, method of characteristics, and variational methods.
In this paper another numerical method is employed. A finite-element method in conjunction with a variational principle for transient heat conduction analysis is briefly reviewed. It is appropriate here to mention the recent successful application of the finite-element method to solve transient heat conduction problems involving either linear, nonlinear, or both boundary conditions. The finite-element method was also applied to transient flow in porous media in a recent paper by Javandel and Witherspoon. Prime references for the method are the papers by Gurtin and Wilson and Nickell. With a slight modification of the solution procedure for treating the convective term as a source term in the transient heat conduction equation, the method can readily be used to obtain numerical solutions of the diffusion-convection equation. Consideration is given to a one-dimensional mass transport problem with dispersion in a porous medium. Results using the finite-element method yield satisfactory solutions comparable with those reported in the literature.
Innovations in Handling and Processing Unconsolidated Cores
Authors: McCollough C.N. 
Published: December 2007

Introduction
Techniques and equipment have been developed for preserving the integrity, of cores from unconsolidated preserving the integrity, of cores from unconsolidated sand reservoirs. New procedures are employed for coring, for removing the cores from the core barrel and handling them at the well site, and for preparing them for sampling in the core processing laboratory and preserving them for future use. The analytical laboratory methods used for drilling plugs with liquid nitrogen and mounting them in triaxially loaded holders are similar to those already reported and will not be discussed here.
The goal of the new techniques is to obtain essentially undisturbed samples in order to determine in the laboratory, under simulated in-situ conditions, such parameters as porosity, permeability, relative permeability, and formation factor, and to establish permeability, and formation factor, and to establish more precise geological and petrophysical relationships from cores.
The need for better data has arisen primarily from the large number of supplemental recovery projects in shallow sand reservoirs in California and elsewhere. These projects created a need for accurate reservoir data not critical during primary depletion. A majority of the shallow oil sands are unconsolidated and there is little or no cohesive strength in the fabric. Frequently when cores are recovered the better quality reservoir rock ends up as piles of sand in the core tray, and only the poorer rock with enough clay or cementation to bind it together can be sampled for laboratory analysis.
P. 1191
Combined Free and Forced Convection in Porous Media
Authors: Combarnous Michel A. , Bia Paul 
Published: December 2007

Abstract
An experimental study of thermal convection in a horizontal porous layer bounded by isothermal planes has been performed with and without a mean flow of the saturating fluid phase. The temperature distribution and heat transfer resulting from convection have been determined.
The theoretical criterion for the onset of convection (Rayleigh number NRa &gt; 4p2) has been verified. For low values of NRa (&lt; 260) a regular pattern of convective cells has been observed which may be motionless or moving depending on the experimental conditions. For NRa values higher than 260, another convective state has been found that is mainly unstable.
Numerical computations have been worked out that confirm the experimental results on the heat transfer and size of convective cells.

Introduction
Thermal convective currents may exist in a porous medium when the vertical component of the temperature gradient runs in the same direction as the gravity vector. Such a configuration is possible in some cases during a real in-situ combustion test4 or during hot fluid injection. A general understanding of convection is also of interest for analyzing the abnormal temperature gradients sometimes observed in oil and gas reservoirs.22
From the phenomenological standpoint a distinction must be made between the natural or free convection occurring in a closed volume and the mixed or combined free and forced convection arising when there is a mean flow of the fluid phase.
Natural convection in porous media has been the subject of numerous experimental attempts to determine a convection criterion, e.g., by using a linear theory,1,2,9 and to measure the mean heat transfer.3,7 Numerical studies8,10,15,19,20 have also been made, and their results are not always in good agreement with experimental observations. However, no thorough study of mixed convection has been made except for a theoretical analysis of the convection onset criterion5 and some qualitative experimental observations.4
This paper presents some findings concerning both the natural and mixed convection of an incompressible fluid in a homogeneous horizontal porous layer bounded by two parallel impervious isothermal surfaces. The temperature for the cooler upper surface is T1 and that of the lower surface is T2=T1+?T.