bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of Rock-Chip Removal by Turbulent Jetting
Authors: Wells M. R. 
Published: December 2007

Summary
The efficiency of the drilling process is largely governed by the efficiency with which the available hydraulics removes rock chips created by the mechanical action of the bit. To date, a physical understanding of the process associated with the hydraulic removal of the chips remains unknown. Rock chips mechanically freed from the parent rock by the drilling action of the bit are generally held in place by overbearing pressures. These pressures must be overcome either by hydraulic action or by mechanical regrinding before the chip may be removed. This work presents the experimental results of a study designed to examine the effects of dynamic forces brought about by jet turbulence on the removal of loose rock chips. Synthetic chips of known shape and size, embedded in a simulated hole bottom and held in place by hydrostatic pressure, were removed solely by the jetting action of a vertically impinging jet. The synthetic chips were flush-mounted into the plate, rendering the shear forces on the surface of the chips at least two orders of magnitude less than the hold-down forces. Measurements of the static jet-impingement pressure and the dynamic fluctuating pressure caused by the jet turbulence were related to turbulent time-scale measurements made using a laser Doppler anemometer, producing an analytical tool to predict the necessary conditions for chip removal. Tests were conducted in both water and an optically clear synthetic clay mixture having non-Newtonian viscosity characteristics similar to a bentonitic fluid. The results indicate that chip hold-down forces can be overcome by the turbulent action of the jet nozzle. Correlations are given indicating the conditions necessary (i.e., jet standoff, radial chip location, chip size, and viscosity) to permit chip removal. These results can be used to place and size jets optimally to maximize chip removal and bottomhole cleaning.
The Effect of Freezing of Slightly Consolidated Cores
Authors: Torsaeter Ole , Beldring Baard 
Published: December 2007

Summary
This paper presents laboratory experimental techniques, procedures, and routine core analysis data of unconsolidated to slightly consolidated core plugs from North Sea reservoirs. The effect of freezing on permeability has been investigated, and results from about 30 core plugs with permeabilities ranging from 0.2 to 12 darcies indicate a considerable change in permeability after freezing. Both increased and decreased permeability were obtained after freezing. For one rock type, the freezing seemed to increase the permeability in cores with initial permeability less than 2 darcies, while decreasing the permeability of core plugs with initial permeability greater than 2 darcies. The observed changes in permeability depend on the amount of kaolinite in the core plugs and the changes in kaolinite morphology during freezing and thawing.
Casing Wear: Laboratory Measurements and Field Predictions
Authors: White Jerry P. , Dawson Rapier 
Published: December 2007

Summary
Casing wear caused by rotation of nonhardbanded tool joints has been investigated with a full-sized test machine. Three grades of casing were used during this study: K55, N80, and PI 10. Tests were conducted in both water-based and oil-based muds. Contact forces between the tool joint and casing were either 1,000 or 2,000 lbf [4.4 or 8.9 kN]. Both the casing wear and friction forces were measured during the tests.
A linear wear-efficiency model was used to correlate the data. This model relates casing-metal removal to the amount of energy dissipated as friction in the wear process. The wear-efficiency model fits the data well and is easily used for field wear predictions.
The data from this study indicate that high-strength casing steels wear more rapidly than K55 and that wear in oil muds is possibly more rapid than in water muds. Partial hydrodynamic lubrication occurred during many tests; friction measurements and the wear-efficiency model were used to account for its effects.
Dispersion and Reservoir Heterogeneity
Authors: Arya Atul , Hewett Tom A. , Larson Ronald G. , Lake Larry W. 
Published: December 2007

Summary
Macroscopic dispersion is the mixing, on the scale of several hundreds of grain diameters, at a point in a permeable medium that is free of boundary effects. Megascopic dispersion is the one-dimensional (1D) dispersion derived by averaging across an entire cross section. This work investigates how both dispersions vary with heterogeneity, aspect ratio, diffusion coefficient, and autocorrelation. The theoretical results are compared to existing field and laboratory data and to existing theories for limiting cases.
The degree of autocorrelation in the medium determines whether or not megascopic dispersivity (dispersion coefficient divided by velocity) is uniquely defined. Large correlation distances (with respect to the medium dimensions) imply a dispersivity that grows with distance traveled. Small correlation distances imply a dispersivity that is eventually stabilized at some constant value. This value is related to the heterogeneity of the medium. On the field scale, diffusion is insignificant, but on a laboratory scale, it can stabilize the dispersivity even if the medium is correlated. Macroscopic dispersivity is sensitive to diffusion in both the laboratory and field scale. It is smaller than or equal to megascopic dispersivity, also in conformance with experimental data, and comparable to laboratory-measured dispersivity.
Radioactive Tracers Monitor Solvent Spreading in Rainbow Vertical Hydrocarbon Miscible Flood
Authors: Mclntyre F. J. , Polkowski G. A. , Bron J. , Pow M. J. 
Published: December 2007

Summary
This paper describes the design, implementation, and results of a tracer project. Three different radioactive tracers (tritiated methane, ethane, and butane) were used to monitor the initial phase of solvent spreading. As a result, adjustments were made to the distribution of injected solvent, ensuring the placement of a stable solvent bank.
Reservoir Engineering in Coal Seams: Part 2—Observations of Gas Movement in Coal Seams
Authors: Gray Ian 
Published: December 2007

Summary
This paper, the second of two concerning the movement of gas in coal seams, covers observations of seam fluid pressures and flows in mines in northern and central Queensland, Australia. Techniques based primarily on underground measurement rather than measurements from surface boreholes were used to gain information on the seams. The techniques used for in-seam studies are described because they differ substantially from conventional oil and gas surface borehole techniques. The paper demonstrates the importance of cleats and joints in the control of fluid movement and records flow increases consistent with increasing permeability with production.
Well Singularities in Reservoir Simulation
Authors: Carey G. F. , Chow S. S. 
Published: December 2007

Summary
In this study, we examine the problem of relating the computed solution at a well in reservoir simulation to the actual bottomhole pressure (BHP) and the related questions concerning determination of an effective radius for the computed pressure. We provide a mathematical analysis of this problem from a slightly different standpoint than that used elsewhere. Our approach provides further insight into the nature of the singularity, the extension to multisingularities, nonuniform grids, and the development of related approximation techniques for radially symmetric nonhomogeneous problems. We present some fundamental new results based on the analysis.
Application of the van Everdingen-Meyer Method for Analyzing Variable-Rate Well Tests
Authors: Whitson C. H. , Søgnesand Sigmund 
Published: December 2007

Summary
This paper discusses application of superposition to pressure-transient analysis when rate varies significantly before and during pressure measurements. To apply rigorous superposition, use of conventional pressure-transient and rate-time methods is recommended to estimate permeability, skin, and in some cases, drainage area. These properties allow calculation of the dimensionless time constant used in superposition calculations on the basis of rate change and dimensionless pressure. As van Everdingen and Meyer proposed, the time constant is varied until a linear fit of the pressure variable is made vs. superposition time. An important step is to use all available rate data, even though pressures may not be measured during periods of rate change. Our work shows the use of full superposition to check the consistency of standard well-test analysis based on the constant-rate or constant-pressure assumption. Data from two gas wells and results from a gas-well simulator provide the basis for our discussion. Problems covered are choosing the dimensionless pressure solution, estimating initial pressure by extrapolation of the superposition plot, and analyzing rate-dependent effects.
Sand Concentration for Maximum Fracture Flow Capacity
Authors: Romero-Juarez Antonio 
Published: December 2007

Abstract
This paper is concerned with the effect of propping-agent concentration on flow capacity of a fracture in the case in which there is embedment of the propping agent. Previous published studies have shown definitely that there is a relationship between fracture flow capacity and propping-agent concentration, and it has been shown that the theoretical results are confirmed by laboratory experiments.
The problem of directly finding sand concentration for maximum flow capacity of a sand-propped fracture is solved, and formulas and charts are given to obtain this concentration under various conditions of effective overburden pressure, medium sand-grain diameter and rock properties. It is shown that, for the same effective overburden pressure and the same rock characteristics, optimum sand concentration in pounds per gallon does not depend on medium sand diameter. For conditions met in hydraulic fracturing operations, it is found that sand concentration in grains per square inch for maximum flow capacity varies within a wide range of values; this indicates the convenience of using data of fracturing pressure and rock characteristics for calculating sand concentration in order to achieve the best results in fracture treatments.

Introduction
It has been pointed out in the published literature that one important factor controls the success of a hydraulic fracturing operation - the propping of the fracture. The main effect of the propping agent is to hold the fracture open by means of the reaction forces that oppose the pressure due to the overburden. It is assumed in this paper that the propping agent is sand, that the grains are spherical and uniform in size, and that this sand is distributed in a monolayer in the fracture.
The existence of a sand concentration value for maximum fracture flow capacity has been recognized since the publication of one of the first studies on the subject. In the reference cited, flow capacity was assumed to be proportional to the cube of the fracture volume per square inch not filled by sand.
A Potentiometric Study of the Effects of Mobility Ratio on Reservoir Flow Patterns
Authors: Bradley H.B. , Heller J.P. , Odeh A.S. 
Published: December 2007

Abstract
A potentiometric model technique is presented for determining the a real sweep efficiency of a five-spot well pattern, at and beyond breakthrough. A sharp interface between displaced and displacing fluids is assumed. Although the prototype system is referred to as a water flood operation, obvious changes in the notation and computations will adapt the results to other displacement processes.
The results of the study include the following.Areal sweep efficiencies for a five-spot well pattern, at and beyond breakthrough, for mobility ratios (displacing to displaced fluid) of 4:1, 2:1, 1:1 and 1:4.Extension of potentiometric analysis to the investigation of the areal sweep-efficiency beyond breakthrough in a five-spot pattern by the application of conformal mapping and conductive-solid models.The use of layers of conductive fabric in representing mobility ratio changes in potentiometric models.The development of a probe mechanism for probing conductive solids.
The results obtained by conductive-cloth models agree with earlier areal sweep efficiencies at breakthrough obtained by Aronofsky and Ramey on the potentiometric analyzer using electrolytic-tank models. Results beyond breakthrough differ from those obtained by the X-Ray Shadowgraph technique. Data from this study show that, for mobility ratios greater than one, water cut rises rapidly as fluid is produced after breakthrough. However, for mobility ratios smaller than one, a large increase in area swept resulted with only a small increase in water cut.

Introduction
In calculating reservoir performance of waterflooding operations and other fluid-injection programs, it is necessary to estimate the areal sweep efficiency before and after injected-fluid breakthrough into production wells. Influence of mobility ratio on oil-production history, before and after breakthrough for a five-spot well pattern, has been studied by X-Ray Shadowgraph techniques and by gelatin models. In none of these investigations was the transition zone controlled experimentally.
Equations for Leak Resistance of API 8-Round Connectors in Tension
Authors: Schwind Brian E. 
Published: December 2007

Summary
This paper presents stress and leak-resistance equations based on the theory of elasticity for API 8-round connectors in tension and compares results of these equations to those of the finite-element method (FEM) and full-scale physical testing. The new equations identify significant nonconservative aspects inherent in current API methodologies.
Surfactant-Enhanced Low-pH Alkaline Flooding
Authors: Peru Deborah A. , Lorenz Philip B. 
Published: December 2007

SummarySodium bicarbonate was investigated as a potential alkaline agent in surfactant-enhanced alkaline flooding because it has very little tendency to dissolve silicate minerals. In experiments performed with Wilmington, CA, crude oil and three types of surfactants, the bicarbonate/surfactant combination caused a marked lowering of interfacial tension (IFT). Bicarbonate protected the surfactant against divalent cations and reduced adsorption of surfactant and polymer on various minerals. Coreflood tests confirm that sodium bicarbonate plus surfactant can be an effective alternative to the high-pH flooding process.
Near-Critical Condensate Fluid Behavior in Porous Media—A Modeling Approach
Authors: Williams John K. , Dawe Richard A. 
Published: December 2007

SummaryRetrograde condensate reservoir behavior is complex, particularly the flow behavior of near-critical fluids, with many of the details of the physical processes involved being a matter of speculation. Conventional coreflooding experiments, while providing indispensable macroscopic data (relative permeabilities, capillary pressure, etc.), are very difficult to carry out under representative reservoir conditions and give little insight into the underlying microscopic processes.Simple physical models can yield many insights into the fundamental pore-scale physics of condensates that may lead to eventual clarification and understanding of the macroscopic processes occurring in the reservoir. The salient features are the use of partially miscible liquid/liquid systems, critical-point universality, and micromodels, giving controlled realizations of porous media. Experimental observations are presented that illustrate pore-scale behavior of near-critical fluids; wettability phenomena and gravity effects are seen to be especially important. Finally, the implications of these observations for macroscopic processes are discussed.
Applications of Real-Time Matrix-Acidizing Evaluation Method
Authors: Prouvost L. P. , Economides M. J. 
Published: December 2007

Summary
A new technique for real-time matrix-acidizing job evaluation has recently been presented that uses reservoir transients during acid injection to simulate pressure response of the unperturbed reservoir and compares simulated pressures with measured values. The difference between these values is attributed to the changing skin effect. An associated pretreatment injection/falloff test is presented as an essential element of that method. It involves injection of an inert fluid (water or reservoir oil) and analysis of the ensuing falloff for a period during which pumping has stopped, just before acid enters the perforations. Injection resumes immediately thereafter.
Two field case studies, a water-injection well in a fissured carbonate reservoir and an oil well completed in a sandstone reservoir, demonstrate the technique. For both treatments, conclusions are drawn regarding the effectiveness of the acid injection. The job evolution is demonstrated, and forecasts of expected well performance for unstimulated and stimulated cases are presented. The skin evolution is shown as a function of injection time. The simulated and measured pressure values for both treatments are shown, indicating the real-time job progression.
Influence of Compound Grease on the Performance of Premium Connections
Authors: Tsuru Eiji , Maruyama Kazushi , Yazakl Youichi , Peters Ekwere J. 
Published: December 2007

SUMMARY
We investigated the harmful effect of compound grease on premium connections. The pressure buildup of compound grease trapped between threads was measured during and after makeup of the connection. The resulting hoop stress in the coupling and the reduction in the seal interference were also measured. Mathematical models were developed to calculate coupling stress and grease pressure. Results indicate that for the conventional API buttress-thread profile, the pressure of trapped compound grease remains permanently high after the connection is made up because of the small thread-clearance area. This high pressure results in a high coupling stress and a large reduction in seal interference diameter, thereby degrading the integrity of the connection. To solve this problem, the thread profile was redesigned with a thread-clearance area larger than that of conventional buttress thread. The connection with the new thread design showed a significantly lower pressure buildup, coupling stress, and seal interference reduction than that with the conventional thread design. Therefore, premium connections with the new thread design are recommended over those with conventional buttress thread design for wells in hostile environments.
Temperature Distribution in Synthetic Diamond Cutters During Orthogonal Rock Cutting
Authors: Prakash V. , Appl F. C. 
Published: December 2007

Summary
A heat-transfer model based on the finite-element method is developed for synthetic polycrystalline-diamond-compact (PDC) cutters used in oil well drill bits. The model is verified by comparison with single-cutter experiments. Effects of process variables, such as film coefficient and diamond thickness, on the temperature distribution in the cutter are studied.
Use of Pattern-Recognition Techniques in Analyzing Downhole Dynamometer Cards
Authors: Dickinson Roderick R. , Jennings James W. 
Published: December 2007

Summary
Four pattern-matching methods are presented to evaluate the downhole condition of sucker-rod-pumped wells. Comparing the generated pump dynagraph of a well being tested to various downhole dynagraphs characteristic of particular rod-pump problems allows the pattern-matching methods to diagnose a variety of different pump conditions. In the future, one of the pattern-matching methods could be incorporated into an automated system designed to monitor the performance of an oilfield's rod-pumped wells.
Permeability Reduction Mechanisms Involved in In-Situ Gelation of a Polyacrylamide/Chromium(VI)/Thiourea System
Authors: McCool C. S. , Green D. W. , Willhite G. Paul 
Published: December 2007

Summary
An investigation of the in-situ gelation of a polyacrylamide/chromium(VI)/thiourea system under flow conditions in unconsolidated sandpacks is presented. High flow resistance was observed in a localized section of the sandpacks that was consistent with deep-bed filtration mechanisms. A method to measure the size of aggregates in a gel solution is also presented. Results from this method showed that the gel aggregates grow with reaction time and distance traveled through the sandpack, supporting the conclusion that filtration is a dominant factor in the in-situ gelation process under flow conditions.
Simulation of the Effects of Mixing in Gasdrive Core Tests of Reservoir Fluids
Authors: Negahban Shahin , Shiralkar Gautam S. , Gupta Surendra P. 
Published: December 2007

Summary
This paper shows that inclusion of a physical dispersion formulation in a fully compositional simulator improves the ability to model and interpret the displacement characteristics of horizontal gasdrive corefloods conducted in 2-in.-diameter, 2- to 32-ft-long, horizontal Berea cores at secondary and tertiary conditions. Foremost among these improvements are (1) quantifying the effects of mixing, characterized by the Peclet number (L/αe), on breakthrough time and displacement efficiency; (2) simulating the effect of core length on miscibility development observed experimentally for multiple-contact-miscible (MCM) displacements with vaporizing/extraction mass transfer, including immiscible behavior in short cores (large mixing) and miscible behavior in long cores (small mixing); and (3) eliminating the need to adjust the number of gridblocks to match coreflood performance.
Development of Correlations To Predict Biopolymer Mobility in Porous Media
Authors: Hejri Shahab , Willhite G. P. , Green D. W. 
Published: December 2007

Summary
This paper describes the flow and rheological behavior of biopolymer solutions in sandpacks over a wide range of permeability and frontal advance rates. Empirical correlations were developed to estimate polymer mobility in porous media. The correlations are based on porous medium properties, polymer concentration, and rheological parameters for the polymer derived from steady-shear measurements.
Review of an Immiscible CO2 Project, Tar Zone, Fault Block V, Wilmington Field, California
Authors: Spivak Allan , Garrison William H. , Nguyen John P. 
Published: December 2007

Summary
The Long Beach Oil Development Co. (LBOD) tertiary immiscible CO2 project began in March 1982 with the injection of a mixture of about 85% CO2/15% N2 into the Tar zone of Fault Block V in the Wilmington field, Los Angeles County, CA. The 330-acre [134-ha] project had been waterflooded since 1961, and the water cut was more than 95%. Gas was injected alternately with water for a period of about 5 years. This paper reviews project performance from inception to the end of 1987.
Pressure-Transient Behavior of Horizontal Wells With and Without Gas Cap or Aquifer
Authors: Kuchuk F. J. , Goode P. A. , Wilkinson D. J. , Thambynayagam R. K. M. 
Published: December 2007

Summary
New analytic solutions are presented in real time and as Laplace transforms for horizontal wells in reservoirs bounded at the top and bottom by horizontal planes. Two types of boundary conditions are considered at these planes, and the Laplace-transform pressure solutions are used to include wellbore-storage and skin effects. Solutions are based on the uniform-flux, line-source solution, but differ from most existing solutions owing to the use of pressure averaging to approximate the infinite-conductivity wellbore condition and use of the correct equivalent wellbore radius for an anisotropic reservoir. New flow periods (regimes) are identified, and simple equations and existence criteria are presented for the various flow periods that can occur during a transient test.