bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diverless Installation of the Skuld Modular Subsea Station
Authors: Freudenreich M. 
Published: December 2007

Summary
In 1984 and 1985, the Skuld experimental station was remotely operated and intensively tested in North Sea conditions for 1 year. This full-scale station, simulating production from a two-well cluster, was installed diverless in June 1984 outside Bergen, Norway, at 90-m [295-ft] water depth. Installation took less than 6 hours per module because we used guidelines and a dedicated landing tool, and the 1-year intensive test confirmed the reliability of the subsea equipment. This experiment demonstrates the validity of the development scheme using the Skuld modular concept.
Magnus Field: Surfactant Stimulation of Water-Injection Wells
Authors: Dymond P. F. , Spurr P. R. 
Published: December 2007

Summary
Water-injection wells in BP's Magnus field are located updip of the oil/water contact (OWC) because of poor aquifer injectivities. A pilot project was undertaken to increase water-injection rates by improving near-wellbore relative permeabilities to water by use of a surfactant to reduce residual oil saturations. This paper discusses the laboratory reservoir-condition coreflood tests, the field monitoring during surfactant treatment, and an interpretation of the success of the project.
A Study of Bulk Cement Handling and Testing Procedures
Authors: Gerke Richard R. , Simon John M. , Logan Jerry L. , Sablns Fred L. 
Published: December 2007

Summary
The variation between thickening-time test results from tests on pilot blends and cement-blend sample tests has been a subject of frequent investigation. Disagreement between these test results is often blamed on improper additive proportioning, inadequate blending, or incorrect sampling techniques.
A comprehensive study of blending, sampling, and testing variables was conducted. This paper describes the results of this research testing with a full-scale laboratory bulk plant. It also includes the results of a south Texas field study in which thickening time test results from more than 300 cement-blend samples were examined. Results of these studies suggest that significant statistical variations may be involved in blending, sampling, and testing procedures under deep-well conditions. The variabilities are used as guidelines for determining thickening-time acceptance windows. Variabilities or uncertainties can be minimized by optimization and standardization of these procedures.
Primary Cementing Improvement by Casing Vibration During Cement Curing Time
Authors: Cooke C. E. , Gonzalez O. J. , Broussard D. J. 
Published: December 2007

Summary
Vibration of casing to improve primary cementing was investigated in the laboratory and in a 200-ft [60-m] deep test well. The effect of vibration is to decrease or to eliminate gel strength of the cement slurry as it is curing. The slurry then flows downward to compensate for shrinkage and re-establishes the hydrostatic head of the cement. This method can prevent pore-fluid entry into the annulus before the cement cures and can increase the radial stress at the interface between the formation and the cured cement.
Effects of Texture on Rheology of Foam Fracturing Fluids
Authors: Harris P. C. 
Published: December 2007

Summary
A new laboratory technique was developed to measure changes in foam texture (bubble-size distribution) vs. foam viscosity in a recirculating pipeline viscometer. Fluid variables studied included foam quality, surfactant type and concentration, gelling-agent concentration, shear history, system pressure, and liquid-phase chemical type.
The viscous properties of foam fluids are determined primarily by quality (internal-phase volume) and liquid-phase properties. The viscosity of an equilibrated foam is influenced by texture to a lesser extent.
Foams are shear-history-dependent fluids. The bubble size and degree of dispersion will adjust to an equilibrium state that depends on time at a given shear rate. Finer-texture foams are produced by higher shear rates, higher surfactant concentrations, and higher pressures. Viscosity measurements at low pressure may not adequately simulate field use at high pressure.
The liquid-phase chemical type influences texture. The structure of methanol and hydrocarbon foams may result in sensitivity to degradation at high shear rates.
Estimation of Productivity of Lobo 6 Sand, Lower Wilcox, Texas, by Identifying Diagenetic Clays With Well Log Data
Authors: Berilgen B. A. , Sinha A. K. , Fertl W. H. 
Published: December 2007

Summary
The laminated, structural, and grain-coating primary clays in the Lower Wilcox Sand, Lobo 6, tend to be potassium-bearing illite and some smectite, whereas diagenetic clays, the cause of pore-throat plugging, are largely potassium-deficient kaolinite and chlorite. These diagenetic clays largely control reservoir permeability, depending on the degree of pore-throat plugging. This paper presents different methods for qualitative and quantitative evaluation of these diagenetic clays, which are related to productivity of the Lobo 6 sand.
Qualitative evaluation consists of crossplot techniques using natural spectral gamma ray and other log data plus selected computed reservoir parameters. For quantitative evaluation, a sophisticated clay-analysis program that uses log-derived cation exchange capacity (CEC) and hydrogen index (HI) values is used. The average volume of different clay types in the zones of interest is calculated, presented, and correlated with production and core data. This approach was used on eight wells on which production data are available to evaluate the presence of diagenetic clays and to estimate productivity of the Lobo 6 sand. The reliability of the log-derived method applied is verified by the excellent correlation with actual production data.
Surfactant Selection With the Three-Parameter Diagram
Authors: Puerto Maura C. , Reed Ronald L. 
Published: December 2007

Summary
A procedure to select surfactants for microemulsion flooding is developed that requires only nominal phase-behavior information, acquired in experiments with pure oils and NaCl brines, provided that the field brine composition, crude oil molar volume, and crude oil hydrogen/carbon ratio are known. It is shown that, for alkylaryl sulfonates, microemulsion phase behavior correlates with ion size and charge rather than with ionic strength alone.
Dynamic Stability of Drillstrings Under Fluctuating Weight on Bit
Authors: Dunayevsky V. A. , Abbassian Fereidoun , Judzis Arnis 
Published: December 2007

Summary
This paper describes the theory and the underlying formulation behind the development of a drillstring-dynamics simulator that predicts rapidly growing lateral vibrations triggered by axially induced bit excitations. The analyses center on calculations of stable rotary speed ranges for a given set of drillstring parameters and are presented in vibration "severity" vs. rotary speed plots. The critical rotary speeds, which correspond to the rapidly growing lateral vibrations, are pinpointed by spikes on the severity plots. Some applications of the drillstring-dynamics simulator are presented, and limitations and further model development are discussed.
Simultaneous Determination of Capillary Pressure and Relative Permeability by Automatic History Matching
Authors: Jennings J. W. , McGregor D. S. , Morse R. A. 
Published: December 2007

SummaryThis paper presents a new method for the simultaneous determination of capillary pressure and relative permeability that is a modification of the porous-plate capillary pressure experiment. The modifications involve the use of thin core samples and thin plastic filtration membranes, resulting in a significantly faster experiment. Relative permeabilities are determined from the experimental data by the use of an automatic history-matching simulator. The new method is found to be particularly well suited for the measurement of small oil relative permeabilities in gas/oil systems.
Evaluation of Low-Resistivity Cased-Off Reserves With the Shale-Compensated Chlorine Log
Authors: Tanner H. L. 
Published: December 2007

Summary
Twenty years of experience accrued from analyzing more than 500 wells has substantiated the overall usefulness of the chlorine logging system. This logging system, developed more than 25 years ago, has proved to be an effective log to run when low-resistivity sands of the U.S. gulf coast area are identified and evaluated.
A Borehole Correction Model for Capture Gamma Ray Spectroscopy Logging Tools
Authors: Grau James A. , Roscoe Bradley A. , Tabanou Jacques R. 
Published: December 2007

Summary
A borehole correction model, based onmore than 1,000 laboratory measurements, has been developed for logging tools that measure gamma ray energy spectra induced by the capture of thermal-energy neutrons. The measurements were made with a field-worthy tool incorporating a pulsed source of 14-MeV neutrons and a NaI(TI) gamma ray detector. In addition to the obvious geometric dependencies on borehole and casing sizes, the sensitivity of the measurement to elements within the borehole was found to depend just as strongly on the porosity and salinity of the borehole and formation fluids. The model decouples the geometric effects from most of the nuclear physics effects by explicitly including the time decay of the neutron flux in each homogeneous region.
Proof of the Two-Phase Steady-State Theory for Flow Through Porous Media
Authors: Chopra Anil K. , Carter Robert D. 
Published: December 2007

Summary
A two-phase steady-state theory presented by O'Dell and Miller1 and modified later by Fussell2 predicts the performance of single-well gas condensate systems when there is liquid condensate dropout. The proof of this theory is developed with material-balance equations and phase equilibrium concepts. In this proof, dispersion, capillary, and gravity effects are neglected. We also show that this theory can be applied to any two-phase hydrocarbon system (e.g., black oil, volatile oil, or gas condensate) when steady-state conditions exist in the vicinity of a single producing well. Results obtained with this theory are compared with the simulation results obtained with a compositional model. A new procedure to compute the in-place composition profiles for systems under steady-state conditions greatly reduces the computation effort because only the phase equilibrium data for the original reservoir fluid are required. Composition profiles calculated with the proposed procedure are identical to the steady-state composition profiles generated with the compositional model. This theory's usefulness for unsteady flow is also illustrated.
The Effects of Mud-Filtrate Invasion on the Interpretation of Induction Logs
Authors: Semmelbeck Mark E. , Holditch S. A. 
Published: December 2007

Summary
A rigorous model of mud-filtrate invasion has been developed with a numerical fluid-flow simulator. This model is used to investigate the effects of certain fluid-flow properties on the invasion process. The model also has the capability to calculate the resistivities that would be measured by deep and medium induction logs. The resistivity measured by the two logs is shown to vary with time, and the difference between the resistivities measured by the two logs is indicative of the amount of invasion that has occurred. This study indicates that multiple logging runs over an interval could be used to evaluate the fluid-flow characteristics of a formation.
Toughness Study of Drillpipes by Use of Instrumented Impact Tests
Authors: Tumuluru Muralidhar 
Published: December 2007

Summary
The toughness behavior of API Grades E and G pipe was studied by use of the instrumented impact test on Charpy V-notch specimens. This study was done at various locations in the pipes, including the upset, nonupset, and transition from upset to nonupset regions. The use of instrumented impact testing made it possible to distinguish the stage of crack initiation from that of propagation during the impact tests. The study revealed that the Grade E pipe possessed poor toughness as evidenced by the low energy values required to propagate the crack. The toughness behavior varied from upset to nonupset regions in the Grade E pipe. The Grade G pipe, on the other hand, exhibited superior toughness uniformly throughout its length as revealed by the high energy values required for crack propagation. Scanning electron microscope (SEM) and metallographic techniques were used to explain the fracture behavior of both types of pipe. The toughness of Grade E pipe, and therefore its tolerance to the presence of defects, can be improved by adopting a quench-and-temper heat treatment.
Recent Developments in the Design of Grouted Connections
Authors: Tebbett I. E. 
Published: December 2007

Summary
A recently completed major research project on the structural behavior of grouted pile/sleeve connections covered static strength, the effect of cyclic movement during grout setting, long-term fatigue, calibration of measured strengths for different quality-control samples, and the investigation of connections removed after 13 years of service in the North Sea. Preliminary data from this project resulted in the issue of revised guidance notes by the U.K. Dept. of Energy and have been recognized in recent amendments to API RP 2A. This paper discusses unpublished test results, the provisions of the latest design codes in relation to the available data, and the implications for design. Results and discussions apply to all types of grouted connections and many types of structures, including pile/sleeve connections for fixed jackets and tension leg platforms and grouted connections used for repair of tubular structures.
Some Invariant Solutions to Two-Phase Fluid Displacement Problems Including Capillary Effect
Authors: Chen Z. X. 
Published: December 2007

Summary
Analytical investigation of the two-phase displacement problem that considers capillary force is one of the most important and difficult problems in the theory of fluid flow through porous media. This paper presents some invariant solutions on the subject, including a self-similar solution for the axisymmetric case, a self-similar solution in a linear, isoclinal reservoir that considers the effects of gravity and capillary forces simultaneously, and a progressive wave solution corresponding to a stabilized zone of saturation distribution. The relations and differences among (1) a model that completely includes capillary effect, (2) a model that considers capillary action partially and implicitly (the Buckley-Leverett model), and (3) a model that completely ignores capillary effect are indicated and discussed.
Stability Theory and Its Use to Optimize Solvent Recovery of Oil
Authors: Perrine Richard L. 
Published: December 2007

Abstract
This paper shows how stability theory can be used to optimize solvent recovery of oil. Application of the theory leads to definition of the limiting conditions required for stable displacement to occur. One of these conditions is that the size of a solvent "slug" must at least equal a prescribed minimum. The criteria to be satisfied are miscibility and stability. Stability implies that no viscous fingering will occur and that mixing will be caused only by a dispersion process. Miscibility implies that complete recovery will be obtained from the swept regions. Thus, for any specified set of reservoir conditions, an optimum use of solvent is defined.

Introduction
The early outlook for solvent flooding as a means to increase oil recovery was very favorable. Some laboratory results indicated that a "slug" containing perhaps 2 to 3 per cent of a hydrocarbon pore volume could be successful. However, other data suggested as much as 30 per cent would be required. The difference is of considerable economic importance. A theoretical explanation for these divergent results has been advanced by the author. Stability theory defines conditions for two distinct flow regimes. In stable displacement, solvent and oil become mixed by a dispersion process, and the solvent requirement is small. On the other hand, unstable displacement can degenerate into viscous fingering. The practical result is a considerable increase in the extent of mixing and, thus, in the solvent required.
The present paper shows how to use stability theory to optimize solvent recovery of oil. Oil is usually considered to be displaced by a small amount, or a slug, of solvent. Gas in turn follows solvent. Any fingering will permit contact of nearly solvent-free gas and oil, leading to immiscibility and reduced recovery. Thus, our optimum is defined by two restrictions - stable flow and miscibility.
A Study of Multiphase Flow Behavior in Vertical Wells
Authors: Hasan A. Rashid , Kabir C. Shah 
Published: December 2007

Summary
This paper presents a physical model for predicting flow pattern, void fraction, and pressure drop during multiphase flow in vertical wells. The hydrodynamic conditions giving rise to various flow patterns are first analyzed. The method for predicting void fraction and pressure drop is then developed. In the development of the equations for pressure gradient, the contribution of the static head, frictional loss, and kinetic energy loss are examined. Laboratory data from various sources show excellent agreement with the model.
Analysis of Gas-Cap or Dissolved-Gas Drive Reservoirs
Authors: Stone H.L. , Garder A.O. 
Published: December 2007

Abstract
A numerical method of solving the partial differential equations which describe the one-dimensional displacement of oil by gas has been presented. Possible extension of the method to treat multidimensional flow is discussed, and the limitations of this extension are indicated. Using this method, it is possible to allow for the existence of a gas cap, the presence of any number of gas-injection or oil-production wells and the evolution of dissolved gas from the oil. It is also possible to allow for variation in the cross-sectional area, elevation, porosity and permeability of the reservoir. The influence of relative permeability and the force of gravity in the direction of flow upon the displacement is considered.
The influence of capillary pressure upon the flow and the effect of gravity in the direction perpendicular to flow are neglected. The physical properties of the fluids are considered to be functions of pressure only, and equilibrium between contiguous phases is assumed.
The numerical calculations can be readily carried out by the use of a digital computer. Several example analyses have been performed using the IBM 704 computer, and about one-third of an hour of computing time was required per case. Reservoir behavior predicted by use of this numerical method was compared to data obtained by other methods for three cases - complete pressure maintenance, dissolved. gas drive and gas-cap drive. The independent solutions to these problems were obtained by analytical solution, laboratory experiment and field data, respectively. Agreement of the numerical solution with data from these sources was good; this agreement establishes the convergence and accuracy of the numerical method.

Introduction
Most petroleum reservoirs can be produced by any one of several alternative programs. When a reservoir is produced by primary methods, production economics can be influenced by controlling the number and location of wells and the flow rate of each well.
The Calculated Performance of Solution-Gas-Drive Reservoirs
Authors: Levine J.S. , Prats M. 
Published: December 2007

Abstract
Several methods are available for calculating the performance of solution-gas-drive reservoirs from the PVT properties of the oil and from the relative permeability and other properties of the formation. These methods require a number of simplifying assumptions. The present method of computation has made use of a high-speed computer to solve simultaneously the nonlinear partial differential equations that describe two-phase flow by solution-gas drive in order to calculate the performance of a reservoir. Some of the results obtained by the nonlinear partial differential equation solution are compared with those obtained with an approximate method, which has been called the semi-steady-state solution. The pressure and saturation profiles from the wellbore to outer boundary calculated by the two methods are compared for one constant-terminal-rate case and two constant-terminal-pressure cases. The agreement in these profiles, as well as in the values of average reservoir pressure and cumulative recovery, leads to the conclusion that, for most engineering calculations, the semi-steady-state method will give a reasonable approximation to the numerical solution of the differential equations describing solution-gas drive.
An unfavorable (as regards ultimate oil production) set of relative permeability curve was used in the calculations in the belief that the effect of the parameters which were studied would be emphasized to a greater degree. Furthermore, the reservoir was assumed to be completely homogeneous, and these results should not be considered applicable to any other type of reservoir. Gravity effects are not considered.
The absolute permeability was varied from 25 to 0.5 md. At an economic limit of 2 B/D, the recovery for a 25-md reservoir is about 1.8 times as great as that for a 0.5-md reservoir. The effect of permeability on the producing gas-oil ratio is minor. Once PVT properties of the oil and the relative permeability properties of the reservoir are fixed, the producing gas-oil ratio is found to be a function of the fraction of oil recovered.
Velocity-Log Interpretation: The Effect of Rock Bulk Compressibility
Authors: Geertsma J. 
Published: December 2007

Abstract
Tbe relationsbip between porosity and the speed of propagation of acoustic waves in fluid-saturated porous rocks as measured by the Sonic log and by ultrasonic techniques is analyzed. Biot's continuum theory is used to explain the difference in acoustic wave propagation between a dry and a liquid-saturated porous material. The porosity is a variable in this theory. However, the acoustic wave propagation in the dry rock depends too on porosity, and this dependence is not predicted by the theory. Frequently in dry sandstones, a nearly linear relationsbip between reciprocal acoustic wave velocity and porosity is observed in the low-porosity range. The physics behind this behavior is outlined. An empirical relationship of the form, 1/V ~ A + B ø, applies accordingly for many porous dry rocks, provided the porosity is the only variable. The presence of a liquid in the pores changes the value of B, and this change is found to be in agreement with the Biot theory.
The time-average relation introduced some years ago results in an equation of the same type 1/V = ø/Vf + (1 - ø)/Vr - but is not based on a sound physical picture. Still, this relation sometimes predicts approximately correct A and B values.
Carbonate rocks with their complicated pore structures sometimes show a different relationship between wave velocity and porosity, unfavorable for log interpretation. Examples are presented. The simultaneous presence of calcite, dolomite and anhydrite, with their different grain densities and matrix compressibilities, complicates acoustic-log interpretation in carbonate rocks still further.
Other complicating effects of acoustic-log interpretation are discussed. They are related to the influence of shale streaks and natural fractures on the average wave velocity observed by the logging tool and to the effect of adsorption phenomena on wave propagation in unstressed rocks particularly in sandstones.