bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Laboratory Study of Wilmington Tar Zone CO2 Injection Project
Authors: Sankur V. , Creek J. L. , DiJulio S. S. , Emanuel A. S. 
Published: December 2007

Summary
We conducted a laboratory study of heavy-oil recovery by CO2 injection to support-the Wilmington, CA tar zone CO2 injection project operated by Long Beach Oil Development Co. The study comprised (1) phase behavior of Wilmington tar zone reservoir oil and CO2, and (2) phase behavior of the oil and the refinery gas used for the field project, (3) viscosity measurements of oil/gas mixtures, (4) reservoir- condition displacements of oil by CO2 and by refinery gas, (5) equation-of-state characterization of phase behavior, and (6) computer simulation of gas/oil displacements.
Saturation pressures'and swelling factors were measured for oil/gas mixtures, which showed that N2 is substantially less soluble in oil than is CO2. Viscosity measurements show that the viscosity reduction is a function of pressure and of the total gas dissolved in the oil.
Four reservoir-condition corefloods showed that the recovery efficiency of CO2 is higher than that of the refinery gas for continuous or low WAG injection, and the recovery efficiency of the refinery gas at 1:1 WAG is about twice that of continuous injection. The corefloods were modeled with a finite-difference compositional simulator. Predictions agree with the experimental results.
Evaluation of Flow Characteristics of Perforations Including Nonlinear Effects With the Finite-Element Method
Authors: Tariq Syed M. 
Published: December 2007

Summary
This study presents results of finite-element modeling of steady-state flow in perforated natural completions. Use of a mesh chosen carefully by grid sensitivity analysis permits evaluation of flow with more precision than that achieved by previous investigators. Also, for the first time, flow characteristics of perforated completions are evaluated with the non-Darcy effect resulting from converging flow around the perforation taken into account. The results indicate (1) confirmation of Locke's results qualitatively but 5 to 10% overprediction by the nomograph, (2) the importance of angular phasing between adjacent perforations, (3) the uncertainty in generally accepted severe permeability impairment in the compacted zone, and (4) a significant reduction in productivity owing to a non-Darcy effect around the perforation for high-rate gas wells.
Response of Wells Producing Layered Reservoirs: Unequal Fracture Length
Authors: Camacho-V. R. G. , Raghavan R. , Reynolds A. C. 
Published: December 2007

Summary
The response of fractured wells producing noncommunicating layered reservoirs is the focus of this work. The conductivity of the fracture is assumed to be finite. The fracture length is assumed to vary from layer to layer. Two modes of production—constant wellbore pressure and constant rate—are considered.
In the first part, the fractures are assumed to communicate only at the wellbore. The results given in this section are intended to provide engineers with analytical capabilities to examine responses in wells where the layers that have been stimulated are separated by considerable distances. Procedures to interpret the results of pressure buildup and/or production tests (drawdown responses) in terms of layer properties are presented. Criteria to ensure maximum productivity are specified. The second part examines well responses when the fractures are in communication at points other than the wellbore. All other things being identical, we show that communication between fractures increases productivity.
Nonlinear Inversion of Pressure-Transient Data
Authors: Hanson Jonathan M. 
Published: December 2007

Summary
Analysis of pressure-transient data is typically carried out with graphical methods that include type-curve, semilog, and log analyses. When sparse and/or noisy data are available, interpretation of pressure transients by graphical means can be difficult. Nonlinear inversion coupled with statistical methods allows model uniqueness and reservoir parameter uncertainty to be quantified under these conditions.
Pressure Core Measurements in Tight Sandstone Lenses During the Multiwell Experiment
Authors: Sattler A. R. , Heckes A. A. , Clark J. A. 
Published: December 2007

SummaryA pressure-coring operation was performed in two tight sandstone lenses of the Mesaverde group during the drilling of one well of DOE's Multiwell Experiment (MWX). The goals were (1) to obtain accurate water saturation data; (2) to measure the amount and composition of gas on a foot-by-foot basis; and (3) to recover fluids for water-chemistry analysis. This application of pressure coring had not been tried before; it was felt to be a novel approach for accurate water-saturation measurements in tight sandstone core.Several changes to usual pressure-coring procedures were adopted, including the development of an organic, noninvasive coring fluid compatible with the oil-based drilling fluid used to help preserve the original water saturation. The pressure-core assembly was modified so that gas samples could be taken directly from the inner barrel and would allow the capture of any gas not trapped during the process; however, none was found. Three 15-ft [4.6-m] -long pressure-core barrels were taken from two sandstone lenses 20 and 30 ft [6.1 and 9.2 m] thick.Water-saturation data were obtained on the pressure core by both Dean-Stark distillation and vacuum-oven drying. The analyses of all recovered core suggest that water-extraction procedures should be carried on for a long time and that the Dean-Stark procedure may not be the water-extraction procedure of choice for tight sandstone core. The failure of one core barrel to hold pressure turned out to provide a bonus, because identical analyses were made on pressurized and unpressurized core from the same sandstone. These analyses showed no appreciable water-saturation difference on rock with the same porosities. No fluid was recovered during thawing alone; the rock was too tight. Gas was obtained in the pressure-coring process and measured on a foot-by-foot basis.
A Combination Air and Fluid Drilling Technique for Zones of Lost Circulation in the Black Warrior Basin
Authors: Graves S. L. , Niederhofer J. D. , Beavers W. M. 
Published: December 2007

Summary
Structural geologic information available for the coal-bearing formations in the Black Warrior basin documents the occurrence of numerous fault and fracture zones. A combination air/fluid drilling technique may be advantageous to coalbed-methane operations in this and other areas with similar hydrologie and geologic conditions. We successfully used this technique recently on coalbed-methane wells in Tuscaloosa County, AL.
Model Investigation of Wellbore Pressure Distribution in Stem-Induced Fracturing
Authors: Fourney W. L. , Holloway D. C. , Simha K. R. Y. 
Published: December 2007

Summary
This paper describes model testing conducted to investigate pressure variations along the length of a wellbore between a decoupled bottom charge and the stem. Tests were conducted in three-dimensional models made from thick plexiglass sheets that contained small decoupled explosive charges in the bottom of the borehole. Charge sizes varied from 75 to 200 mg, and the open borehole length between the top of the charge and the stem ranged from three to seven times the charge length. Both top and bottom charge initiations were investigated. Multiple pressure transducers were used along the borehore, and pressure/time distributions were determined at several locations.
An additional series of tests is described in which the borehole geometry was altered by varying the diameter of an orifice plate placed in the wellbore. The use of this orifice plate was demonstrated to be effective in controlling the increase rate of the pressure pulse at the stem location.
Success in Prevention of Casing Failures Opposite Salts, Little Knife Field, North Dakota
Authors: Rike E. A. , Bryant G. A. , Williams S. D. 
Published: December 2007

Summary
We became aware in early 1981 of a severe problem with casing failures opposite salts in the Little Knife field. A concerted engineering effort was initiated to isolate and to remedy the cause of failures. With the use of a relaxed invert-oil-emulsion drilling fluid and properly designed cementing programs, the problem has been arrested. In the 26 wells drilled in the Little Knife field since initiation of this drilling program, there have been no instances of casing failure.
Type Curves for Finite Radial and Linear Gas-Flow Systems: Constant-Terminal-Pressure Case
Authors: Carter Robert D. 
Published: December 2007

Abstract
This paper presents gas-prpduction-rate results in type curve form for finite radial and linear flow systems produced at a constant terminal (bottomhole) pressure. These results can be used in the analysis of acfual gas and oil rate/time data to estimate reservoir size and to infer reservoir shape. The type curves are based on dimensionless variables that are a generalized form of those presented previously.1,2 In addition, an approximate drawdown parameter is presented. Example applications that demonstrate the applicability of the type curves to a variety of reservoir configurations are given. The Appendix contains derivations of the dimensionless variables and the drawdown parameter.
A New Jet Perforating Charge Eliminates Carrot Plugging
Authors: Robinson R.L. , De Frank Pete , Hatfield R.F. 
Published: December 2007

Introduction
Production equal to or greater than open-hole completions is possible through perforated completions if the flow paths throughout the perforations are free of obstructions. Previous investigations have indicated that, in some cases, maximum productivity is not obtained due to plugging of the perforations with debris from the wellbore fluid and/or debris from the perforating process. Control of wellbore fluid and proper well completion techniques are very important in the elimination of perforation plugging. Selection of properly designed perforating equipment also is quite important for maximum well productivity.
Studies made with the use of the perforation flow laboratory, in which perforating tests are run under simulated well conditions, have shown that perforation plugging occasionally occurs. Plugs in perforations result from various causes. One of the contributors to plugging that can be controlled by the perforating device is the slug or carrot resulting from jet perforating. This condition has undergone extensive study, and previous developments have resulted in a decrease in carrot size-but not in complete elimination. It was felt that, if a method of completely eliminating the carrot could be found (with charge performance equal or better than previously obtained), a significant contribution would have been made. Such a charge has been developed and is reviewed in this paper.

Theoretical Considerations of Carrot Elimination
There are several popular theories of how a shaped charge jet is formed. One of these is the hydrodynamic theory, wherein the liner is treated as a fluid under the impact of the explosive forces. Another is the spalling theory, where the interaction of shock waves in the liner causes small particles to be torn from the inner surface of the liner and projected at high velocity toward a common focal line to form the jet. It is not unreasonable to assume that both of these theories may be partially correct. For purposes of our discussion, it is simpler to use the second theory.
A Ternary, Two-Phase, Mathematical Model of Oil Recovery With Surfactant Systems
Authors: Thomas Charles P. , Fleming Paul D. , Winter William K. 
Published: December 2007

AbstractA mathematical model describing one-dimensional (1D), isothermal flow of a ternary, two-phase surfactant system in isotropic porous media is presented along with numerical solutions of special cases. These solutions exhibit oil recovery profiles similar to those observed in laboratory tests of oil displacement by surfactant systems in cores. The model includes the effects of surfactant transfer between aqueous and hydrocarbon phases and both reversible and irreversible surfactant adsorption by the porous medium. The effects of capillary pressure and diffusion are ignored, however. The model is based on relative permeability concepts and employs a family of relative permeability curves that incorporate the effects of surfactant concentration on interfacial tension (IFT), the viscosity of the phases, and the volumetric flow rate.A numerical procedure was developed that results in two finite difference equations that are accurate to second order in the timestep size and first order in the spacestep size and allows explicit calculation of phase saturations and surfactant concentrations as a function of space and time variables. Numerical dispersion (truncation error) present in the two equations tends to mimic the neglected effects of capillary pressure and diffusion. The effective diffusion constants associated with this effect are proportional to the spacestep size.
New Developments in Induction and Sonic Logging
Authors: Tixier M.P. , Alger R.P. , Tanguy D.R. 
Published: December 2007

Abstract
In the combination induction-electrical log used at present in the field, the induction logging tool is appropriate for the investigation of moderately invaded formations. A new induction sonde with a radius and investigation about twice as large has been developed recently for the case of deep invasion. It has very nearly the same vertical resolution as the present sonde so that thin beds are defined as accurately as before. The characteristics of the new tool are described, the corresponding interpretation charts are given and field examples are discussed.
The design of the sonic logging tool has been modified to improve the calibration and the reliability. The fact that porosity can be accurately recorded by means of the sonic log has prompted new interpretation. procedures for saturation estimation, wherein the data concerning the various permeable beds in a given well are correlated.
One approach consists of plotting transit time vs true resistivity, with an appropriate scale. With this approach, saturations can be estimated conveniently even in cases where formation water resistivity is not well known.
In another approach, a comparison is made of the values of the formation waters computed from the resistivity and sonic logs. Using the concept of continuity, this procedure makes possible a quick determination of zones of saturation in shaly sands and/or in case of appreciable variations of formation salinities with depth.
It has been found that the comparison of porosity from the sonic log with the apparent porosity computed from a short-investigation resistivity log may reveal, in many cases, the presence of residual oil and thus detect potentially productive formations; this procedure is valuable when the true formation resistivity and the resistivity of the formation water are in doubt.

Introduction
During the past year, the efficiency of log interpretation has been vastly improved. The improvements have largely resulted from the introduction of a deep-investigation induction device and from the application of new interpretation techniques that utilize sonic vs resistivity readings. Since the new interpretation techniques depend, in part, upon good values of true formation resistivity, the new induction log will be discussed under Part I. The sonic interpretation techniques will be studied under Part II.
Development of a Fluorimetric Method for Detection of Pay Zones During Drilling With Invert Muds
Authors: Connell D. L. , Coates J. A. , Frost D. A. 
Published: December 2007

Summary
An examination of possible pay-zone detection techniques was prompted by the introduction of low-toxicity oil muds. Infrared (IR) spectroscopy, thin-layer chromatography (TLC), and fluorimetry are shown to be applicable. Fluorimetry is preferred for its better sensitivity and ease of use offshore. We examine the requirements for use of the technique in the field.
A Study of Mineral/Alkali Reactions
Authors: Mohnot S. M. , Bae J. H. , Foley W. L 
Published: December 2007

Summary
A study of the reaction of alkaline chemicals with minerals constituting reservoir rock is presented. Static tests were conducted with high concentrations of NaOH and orthosilicate solutions and minerals (montmorillonite, kaolinite, illite, and quartz sand). The reaction time varied from 10 minutes to 2 months. Solutions were analyzed for hydroxide, Si, and Al, and solids were analyzed by X-ray diffraction (XRD) and other spectroscopic techniques. The loss of useful alkalinity was the highest with kaolinite and the least with quartz sand for high alkali concentration (5 wt%) or temperature (180°F [82 °C]). A detailed study of kaolinite/alkali reaction kinetics and quartz/alkali equilibrium is presented.
Optimal Spacing for Casing Centralizers
Authors: Lee H. K. , Smith U. C. , Tighe R. E. 
Published: December 2007

Summary
In the placement of centralizers on casing, it is necessary to integrate information on hole trajectory, casing properties, and centralizer performance. This paper summarizes the basic theory and algorithms for optimizing centralizer spacing based on these considerations. The algorithm predicts the wall forces in a three-dimensional (3D) borehole.
Although centralizer placement is important in all wells, it is especially important for highly deviated boreholes and deep, heavy strings. With the detailed approach described here, centralizer placement design gives the operator greater confidence in the prediction of minimum standoff distance for these types of wells.
Some examples of field applications are presented. Also, cementing results from field wells support the conclusion that good cement placement is obtained when adequate centralizers are used.
Pressure Falloff Behavior in Vertically Fractured Wells: Non-Newtonian Power-Law Fluids
Authors: Vongvuthipornchai S. , Raghavan R. 
Published: December 2007

SummaryThis paper examines pressure falloff behavior in fractured wells after the injection of a non-Newtonian power-law fluid. Results are presented in a form suitable for field application. Responses at wells intercepting infinite-conductivity and uniform-flux fractures are considered. Procedures to identify flow regimes are discussed. The solutions presented here are new and to the best of our knowledge are not available in the literature. The consequences of neglecting the non-Newtonian characteristics of the injected fluid are examined.Although the main objective of our work is to examine pressure falloff behavior at fractured wells, we also examine responses at unfractured wells. This part of our study examines the validity of using the superposition principle to analyze pressure falloff data. (The pressure distribution for this problem is governed by a nonlinear partial-differential equation.) If the solutions given in the literature are used, then correction factors are needed to analyze pressure falloff data. The results of this phase of our work can also be used to analyze data in fractured wells provided that pseudoradial flow conditions exist.
Gas Well Test Analysis: Use of Normalized Pseudovariables
Authors: Meunier D. F. , Kabir C. S. , Wittmann M. J. 
Published: December 2007

Summary
Pressure data from gas wells are normally analyzed by use of pseudopressure, which is a transformation of measured pressure. When tests are associated with large pressure changes accompanied by a severe wellbore storage effect, such as in tight reservoirs, use is made of pseudopressure and pseudotime transforms. The purpose of the pseudovariables is to linearize "effectively" the governing diffusivity equation so that proper test interpretation can be made.
In this study, normalized pseudovariables or transforms are introduced. Use of these new pseudovariables produces results identical to those obtained with the conventional pseudovariables. However, the proposed pseudovariables offer some distinct practical advantages. For example, units of pressure and time are retained, thus giving a physical "feel" for the pseudovariable definitions. Other features include use of liquid equations for solving the gas flow problems—i.e., constants of the working equations remain unchanged.
This study also proposes two methods for estimating the rate-dependent skin, together with permeability, mechanical skin, and well deliverability. The first method involves logarithmic convolution of pressure with flow rate, both measured downhole, by use of a radial model. A trial-and-error approach is used to obtain the rate-dependent skin on a convolution plot. The second method requires a transient flow-after-flow test of short duration; a standard graphic technique allows the estimation of the desired reservoir parameters.
Once the reservoir parameters are estimated with either method, the absolute open-flow potential (AOFP) of a well can be established by assuming a reservoir radius because the AOFP is relatively insensitive to this assumption.
Drilling Techniques Improve Success in Drilling and Casing Deep Overthrust Belt Salt
Authors: Unger K. W. , Howard D. C. 
Published: December 2007

Summary
One of the most challenging drilling problems encountered in the Western Overthrust belt occurs in the deep Jurassic Preuss salt. A history of lost holes caused by stuck drillstrings, stuck casing, and collapsed casing plagues operators in the Wyoming/Utah Overthrust belt. An ongoing engineering study is being conducted to identify the problem salt-drilling areas and to solve the associated drilling and casing-collapse problems.
In the first part of this study, completed in June 1983, salt-drilling problems were studied in the Anschutz Ranch East field. Problem intervals within the salt section were identified, and unique salt-drilling techniques were developed. As a result of implementation of the salt-drilling techniques, salt-drilling success in Anschutz Ranch East has improved substantially.
Included in this study are an evaluation and recommendations for mud systems, bottomhole assemblies (BHA's), drilling parameters, and caliper logging through the salt interval. Casing collapse caused by nonuniform loading is discussed, and preventive measures are recommended.
Review of PDC Bits Run With Invert-Emulsion Oil Mud in Shallow South Texas Wells
Authors: McClelland G. M. 
Published: December 2007

Summary
This paper examines 56 polycrystalline-diamond-compact (PDC) bit runs, discusses the evolution of the PDC bit, and recommends guidelines for selecting the most economical bit design for shallow south Texas wells drilled with invert-emulsion oil mud. From March 1981 to April 1984, our South Texas Div. Drilling documented 88 PDC bit runs with invert-emulsion oil mud in shallow south Texas wells. These PDC bits primarily drilled soft Frio formations of sand and shale to less than 12,000 ft [3660 m] total depth (TD). Throughout this time, PDC bit design continually improved, providing progressively greater time and cost savings. Field data indicated that improvements in bit material, body design, cutter placement, and operating procedures have increased rates of penetration (ROP's) and bit life, thus decreasing drilling costs.
Three-Parameter Modification of the Peng-Robinson Equation of State To Improve Volumetric Predictions
Authors: Jhaveri Bharat S. , Youngren Gary K. 
Published: December 2007

Summary
The Péneloux-Rauzy-Fréze (PRF) method of improving volumetric predictions by introducing a third parameter into a two-parameter equation of state (EOS) is applied to the Peng-Robinson EOS (PR-EOS). The modified PR-EOS is evaluated for application to hydrocarbon fluids. A method is developed for characterizing the third parameter for the heptanes-plus fractions. The usefulness of the modified PR-EOS in improving volumetric predictions is illustrated by applying the equation to several crude-oil and gas-condensate systems from the literature.