bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Correlation of the Viscosity of Hydrocarbon Systems With Pressure, Temperature and Composition
Authors: Little J.E. , Kennedy H.T. 
Published: December 2007

Abstract
An empirical equation for the prediction of the viscosity of several pure paraffin hydrocarbons and nitrogen is presented. It involves temperature, pressure and six constants of the material, and it applies reliably to both liquids and gases. The equation is similar in form to van der Waal's equation of state. For the paraffin hydrocarbons methane through n-hexane and nitrogen, an average absolute deviation of 1.9 percent was obtained on 1,006 data points described in the literature by 14 authors. When this equation is extended to complex, liquid hydrocarbon mixtures, a correlation was obtained with an average absolute deviation of 9.9 percent.

Introduction
Equations describing the flow of gas and liquid through porous media contain the viscosity coefficient of the fluid. If other pertinent variables remain constant, the volume rate of flow is inversely proportional to this coefficient. In dealing with condensate fluids and volatile oils, however, the compositional effects resulting from changing pressure materially affect the viscosity. The effect of compositional changes also may be significant in certain secondary recovery or pressure maintenance processes, notably miscible displacement or gas injection. Early attempts to describe the performance of reservoirs utilized a volumetric material balance method wherein gas and liquid in the reservoir were identified as produced gas and liquid at the surface. This method of analysis proved adequate for reservoirs at moderate temperature and pressure that contained gas with moderately low amounts of condensable materials. The volumetric material balance procedures for "black oil" reservoirs leave much to be desired when applied to condensate and volatile oil reservoirs because phase behavior and compositional changes the relatively more important in these cases. The alternative is a compositional material balance, which in turn, requires a correlation of properties of the reservoir fluid with composition. This paper supplies this correlation in regard to viscosity, for reservoir crude oils.

REVIEW OF LITERATURE
The literature contains many empirical equations describing the effects of composition, temperature and pressure on the viscosities of pure liquids and binary liquid mixtures. However, the applicability of a majority of these equations is limited to very low pressures and to a small number of systems. Most of the, when applied to complex hydrocarbon systems, are of little value. The lack of utility of the majority of equations results from the fact that they were developed to show the separate effect of temperature, pressure or composition on viscosity, but not to predict the viscosity as a function of all three variables. And with the few exceptions noted below, they were developed to apply to much simpler systems than hydrocarbon mixtures.
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Advanced Techniques Improve Liner Cementation in North Sea Wells: An Operator's Experience
Authors: Buchan R. , Little M. T. S. 
Published: December 2007

SummaryImprovements in liner cementation in the North Sea are being made through optimization of cementing practices and the use of advanced technology, which includes liner rotation during hole conditioning and cementing. This paper reviews our experiences and discusses key aspects of liner rotation, including equipment selection, job design, and implementation. Comparison of cement-bond logs (CBL's) with those from nonrotated-liner cement jobs shows that liner rotation during cementing can greatly improve results.
Estimation of Effective Permeabilities in the Lower Stevens Formation of the Paloma Field, San Joaquin Valley, California
Authors: Desbarats Alexander 
Published: December 2007

Summary
Simulation programs used in reservoir studies require effective gridblock permeability values representing spatial averages over large volumes of formation. Within such volumes, most reservoir rocks exhibit a considerable degree of heterogeneity, with permeability measurements often varying over several orders of magnitude. A satisfactory method for averaging permeabilities must consider not only the magnitude of permeability variations, but also the variations of permeability in space. Using experimental histograms and variograms to describe the heterogeneous permeability field within gridblocks, a Monte Carlo technique is used to estimate effective permeability. The method is illustrated by an example with actual permeability data from the lower Stevens formation of the Paloma field in Kern County, CA. Experimental downhole variograms of permeability showed a large nugget effect at short lags and a longer correlation structure with a range of 100 ft [30 m]. For the particular distribution and spatial correlation structure of these data, effective horizontal and vertical permeabilities were found to be respectively higher and lower than the geometric mean. Calculated effective permeabilities were found to be relatively insensitive to assumptions regarding the horizontal range of spatial correlation. This lack of sensitivity is caused by the large nugget effect or random short-range correlation structure. Effective permeabilities obtained with an approximate analytical relation were compared with effective permeabilities calculated numerically.
Impulse Testing
Authors: Ayoub J. A. , Bourdet D. P. , Chauvel Y. L. 
Published: December 2007

Summary
This paper proposes a new method for evaluating hydrocarbon wells. The formation is subjected to a rate impulse created by briefly flowing the well or injecting into the formation. The pressure response to an ideal rate impulse (i.e., to an instantaneous source of strength unity) is given by the derivative of the pressure response to a conventional step-rate change. This general solution is used in developing an interpretation method based on recently published type curves of the derivative of pressure.
Impulse™ testing is particularly useful for wells that do not flow to the surface and for wells where extended flow may not be desirable (because of sand problems, for example). Applied in conjunction with underbalanced perforating, this method provides a low-cost evaluation of the reservoir and wellbore condition. Several field examples are presented to illustrate the analysis technique.
Model Selection for Well Test and Production Data Analysis
Authors: Watson A. T. , Gatens J. M. , Lane H. S. 
Published: December 2007

Summary
The estimation of reservoir properties from production or pressure data measured during production or well tests is an important process for reservoir characterization and performance prediction. A key step in that process is the selection of a reservoir model for use in the interpretation of the data. We develop a procedure for selecting the most appropriate model from a pool of candidates. A parameter estimation algorithm is used to evaluate parameters within candidate models. Statistical measures are then used to select the most appropriate model.
We demonstrate our procedure for model selection with actual well test data and production data from the Devonian shale. We show how our methodology can be used to evaluate whether certain reservoir features can be identified from measured production or pressure data. We also present a test for evaluating whether independent estimates of reservoir properties are consistent with measured pressure and production data.
A New Technique for Analyzing Buildup Tests From Hydraulically Fractured Wells
Authors: Rahim Zillur , Lee W. John 
Published: December 2007

Summary
This paper presents a new iterative technique for interpreting early-time pressure-buildup data for hydraulically fractured wells. The technique uses a modified square-root-of-time analysis with permeability and fracture-length correction curves generated from Cinco-Ley et al.' s solution to flow equations for finite-conductivity fractures. The method is applicable to low-permeability reservoirs where conventional methods of analysis are difficult to apply.
Production-Systems Analysis for Fractured Wells
Authors: Hunt James L. 
Published: December 2007

Summary
Production-systems analysis has been in use for many years to design completion configurations on the basis of an expected reservoir capacity. The most common equations used for the reservoir calculations are for steady-state radial flow.
Most hydraulically fractured wells require the use of an unsteady-state production simulator to predict the higher flow rates associated with the stimulated well. These high flow rates may present problems with excessive pressure drops through production tubing designed for radial-flow production. Therefore, the unsteady-state nature of fractured-well production precludes the use of steady-state radial-flow inflow performance relationships (IPR’s) to calculate reservoir performance. An accurate prediction of fractured-well production must be made to design the most economically efficient production configuration.
It has been suggested in the literature that a normalized reference curve can be used to generate the IPR’s necessary for production-systems analysis. However, this work shows that the reference curve for fractured-well response becomes time-dependent when reservoir boundaries are considered. A general approach for constructing IPR curves is presented, and the use of an unsteady-state fractured-well-production simulator coupled with the production-systems-analysis approach is described. A field case demonstrates the application of this method to fractured wells.
A Mathematical Model for Pressure Evaluation in an Infinite-Conductivity Horizontal Well
Authors: Rosa Adalberte J. , Carvalho Renate de Souza 
Published: December 2007

Summary
A mathematical model was developed to study the transient pressure behavior in a well with an infinite-conductivity horizontal drainhole in an infinite slab reservoir. The physical model includes a fluid of small and constant compressibility flowing through an infinitely large anisotropic reservoir with upper and lower impermeable boundaries. The analytical solution is obtained by applying the concepts of instantaneous sources and Green's functions.
We discuss the uniform-flux model, a special case of the infinite-conductivity model, and present a simple way to use it to calculate the pressure at the wellbore face. We suggest that the pressure for the infinite-conductivity case can be evaluated with the uniform flux model at a fixed point along the wellbore with an error of less than 1 % for combinations of the various parameters that may be encountered in real situations. We show to what extent the accuracy of the model will be affected by neglecting gravitational effects.
New Analytical and Numerical Solutions for the Radial Convection-Dispersion Problem
Authors: Tang D. H. E. , Peaceman D. W. 
Published: December 2007

Summary
New analytical and numerical solutions are presented for the radial convection-dispersion differential equation with a velocity-dependent dispersion coefficient. The finite-difference numerical scheme is shown to have negligible numerical dispersion for this problem. Very close agreement is obtained between the analytical and numerical solutions. The effect of the type of boundary condition used at the wellbore is discussed.
A New Computational Approach to the Miscible Displacement Problem
Authors: Hatzlavramidis Dimitri T. 
Published: December 2007

Summary
A 2D miscible displacement computer code based on a pseudospectral method that uses Chebyshev expansions and a grid adaptive to the position of the front was developed. In this method, the effect of physical dispersion is explicitly included, while the effect of numerical dispersion is greatly suppressed. The code was shown to have exceptional convergence, accuracy, stability, and computational economy. It accurately predicts the position and sharpness of the displacement front for ID miscible and immiscible displacements. The code also predicts oil recoveries and breakthrough times for 2D miscible displacements with unfavorable mobility ratios that are in agreement with experimental data and is shown to be effective in resolving details of viscous fingering phenomena.
Typical Features of a Multipurpose Reservoir Simulator
Authors: Quandalle P. , Sabathier J. C. 
Published: December 2007

Summary
This paper describes a new three-dimensional (3D), three-phase, multipurpose reservoir simulator. An extensive description is given of the dual-porosity facility. Three user-selected options available for computing the material transfers between matrix and fractures are developed and discussed. The most sophisticated option accurately accounts for the capillary, gravity, and viscous forces. A simplified thermodynamical package is also presented and examples are given.
A Practical Evaluation of Nondestructive Tubular Inspection Units: Methods and Results
Authors: Reynolds Bruce W. , Gill L. Owen 
Published: December 2007

Summary
This paper describes a program for evaluating flaw-detection capabilities of electromagnetic inspection (EMI) and ultrasonic inspection (UT) units used in oil-country tubular goods (OCTG) inspection. The test program involves use of two 7-in. [17.78-cm] joints of casing; each contains various OD and ID defects. The test procedures are similar to those used by other major operators, but the scope, design, and quality-control measures of Chevron's program make it unique. Results are presented for the 73 evaluations conducted to date, which indicate a two-to-one superiority of UT units in flaw-detection capabilities. The relatively poor performance of EMI inspection prompted re-evaluation of the use of this type of service for OCTG body wall inspection.
BOP Shear Rams for Hydrogen Sulfide Service
Authors: Canal J. R. 
Published: December 2007

Summary
The shear rams in a blowout preventer (BOP) are critical components of the drilling system, which is expected to shear drillpipe and to seal the wellbore in all types of drilling fluids. The brittleness of high-strength tool steels when exposed to wellbore fluids containing H2S has been recognized for many years by the drilling industry. The development in recent years of high-strength materials that are resistant to hydrogen embrittlement has made possible the manufacture of H2S-resistant shear rams. This paper describes the fabrication of such shear rams. The cutting edge is made from a cobalt base (UNS R30035) and an iron-based superalloy (UNS S66286) joined by an electron-beam (EB) welding process. The discussion continues with the shearing tests of API 5A Grades E, G, and S-135 drillpipe of two wall thicknesses with a 13%-in. [346-mm], 10,000-psi [69-MPa] working-pressure (WP) ram BOP.
Methods for Handling Drilled Gas in Oil-Based Drilling Fluids
Authors: O’Bryan P. L. , Bourgoyne A. T. 
Published: December 2007

SummaryThis paper presents calculation methods for predicting the behavior of drilled-gas contamination of oil-based drilling fluids. The methods are verified by experiments conducted in a 6,000-ft [1828.8-m] test well. This paper also presents field-handling procedures developed with the calculation methods.
Comparison of Field and Laboratory-Simulated Drill-Off Tests
Authors: Bourdon J.-C. , Cooper G. A. , Curry D. A. , McCann D. , Peltier B. 
Published: December 2007

Summary
Field drill-off test results are compared with data from laboratory simulations. A simple theory for analyzing drill-off tests is developed. The weight-on-bit (WOB) decay with time is close to exponential, but large threshold WOB's, resulting from poor weight transmission downhoie, are sometimes observed in field tests.
Planning and Operational Requirements for a Shallow-Objective, High-Angle Well in the Gulf of Mexico
Authors: Christian D. B. 
Published: December 2007

Summary
This paper is a case history of a highly deviated exploratory well in East Cameron Block 378. This well was difficult because it is located in the middle of a shipping fairway. Planning and engineering requirements for the successful completion of the well are discussed. Highlights include the directional plan, casing design, measurement while drilling (MWD) for directional information and formation evaluation, drilling fluids, and rig selection.
Surface Equipment Cleanup Using In-Situ Heat
Authors: Collesi Jacqueline B. , Scott Thomas A. , McSpaddon Hal W. 
Published: December 2007

Summary
A chemical system capable of generating heat in situ has been used to remove hydrocarbon deposits, mainly paraffin, from surface equipment and flowlines in the U.S. gulf coast. The treatments resulted in increased production throughout the structures. The chemical system, treatment design, case histories, and results are discussed.
Formation Damage Related to Hot Oiling
Authors: Barker K. M. 
Published: December 2007

Summary
Hot oil has been used to remove paraffin deposits almost as long as oil has been produced. It is still the most widely used procedure for paraffin removal in use today because of its relative simplicity of application, immediate results, and low cost per application. These apparent benefits have obscured the damage that hot oil can cause when used to clean downhole production equipment.
Formation damage caused by hot oiling is related to the physical characteristics of the oil used, the source of the oil, the formation temperature, and the hot-oil process. Potential problems are discussed and suggestions made to minimize or to eliminate them. Laboratory tests are presented for determining whether a crude will cause formation damage during hot oiling. Case histories of successful cleaning of hot-oil formation damage are also given.
A Kinetic Model of CO2 Generation and Mineral and Isotopic Alteration During Steamflooding
Authors: Cathles L. M. , Schoell Martin , Simon Ralph 
Published: December 2007

Summary
CO2 is commonly produced during steamflooding. In higher-temperature steamfloods the amount of CO2 produced is such that the only viable source is carbonate minerals. We show by reference to CO2 concentrations in natural geothermal systems that in most common rocks and sediments, CO2 is generated naturally under hydrothermal (~572°F) conditions by the dissolution of carbonate minerals. CO2 solubility is a strong positive function of temperature and, at 572°F, is more than sufficient to account for high CO2 concentrations like those encountered at Chevron's Buena Vista (BV) Hills steamflood pilot test. A linear kinetic model is developed to describe chemical equilibration and CO2 generation in the hot parts of the reservoir. The model also describes CO2 removal through carbonate precipitation in the cooler parts of the rock formation where the fluid moves ahead of the thermal front. Changes in carbon isotope concentration are included in the model. The small difference between the 13C in the produced gas and the source carbonates at BV Hills suggests that little CO2 is precipitated as carbonate within that reservoir, a prediction that can be tested by poststeamflood coring.
Evaluation of Microbial Systems in Porous Media for EOR
Authors: Bryant Rebecca S. , Douglas Jonell 
Published: December 2007

Summary
The use of microorganisms to enhance oil recovery has become a technically feasible technology for production from stripper wells (those that produce less than 10 B/D [1.6 m3/d]). As a result of microbial growth and the production of CO2 and/or chemicals, oil recovery can be effectively increased in certain reservoirs with temperatures and salinities hospitable to microorganisms.
Research at the Natl. Inst, for Petroleum and Energy Research has led to development of laboratory facilities for evaluating microbial systems for microbial enhanced oil recovery (MEOR) applications. Results from microbial core studies using Berea sandstone have shown that bacteria can vary greatly in their ability to recover residual oil after waterflooding, giving from 7.5 to 71 % recovery efficiency. The type of core encapsulation did not affect oil recovery. Variations in rock permeability from 134 to 1,920 md indicated that some microorganisms may exhibit a better recovery efficiency in lower-permeability cores. The results also show that gas production by microorganisms is not the only factor affecting oil recovery; some bacteria that produce surfactants but no gas could provide equally efficient additional oil recoveries. Likewise, the type of surfactant also makes a difference; two species that produce surfactants can vary in recovery efficiency. Another contributing mechanism to microbial oil mobilization may be by increasing areal sweep efficiency from microbial growth. A comparison of oil recovery efficiencies between microorganisms using a medium-to-light-gravity oil (Delaware-Childers) and two heavy oils (Wilmington, CA, and Chaffee, CA) indicates that MEOR may be effective for heavy oils as well as light oils. Correlations are presented between the recovery efficiency of a particular microbial species and its ability to mobilize crude oil in etched-glass micromodels.
Effects of Shutting In Injectors on Steamflood Performance
Authors: Hong K. C. 
Published: December 2007

Summary
The effects of temporarily shutting in steam injection wells on oil recovery by steamflooding were studied with a steam injection simulator. Both heavy- and light-oil steamflood situations were considered. A one-eighth of a five-spot model representing the two types of reservoirs was used to study the effects of shutting in the injector for up to 8 months on the oil production performance during the shut-in period and following the resumption of steam injection.
The simulation results show that temporarily shutting in injectors is not detrimental to overall oil recovery. For each type of reservoir (heavy or light oil), the cumulative oil production at a limiting instantaneous steam/oil ratio (SOR) of 10 was essentially the same regardless of the length of injector shut-in. The cumulative SOR at the end of the project life also remains the same, regardless of the length of shut-in. Shutting in the injector, however, prolongs the project life, increasing it by about the length of shut-in for the heavy oil and by more than the length of shut-in for the light-oil case.
This paper compares oil production performances for steamflood projects operating under different shut-in scenarios and recommends strategies to cope with the changing economic environment.
Reliability of Laboratory Measurement of Porosity in Tight Gas Sands
Authors: Luffel D. L. , Howard W. E. 
Published: December 2007

Summary
A study was conducted to verify or to improve the routine laboratory procedures normally used to measure porosities of cores from tight gas sands. After routine analysis of 242 core plugs from the Travis Peak formation in east Texas, 20 of the plugs were analyzed for porosity by two additional laboratories. Each of the three laboratories had problems with their results that normally would have gone unnoticed but were recognized because of disagreement with results from the other laboratories. After reruns, agreement was excellent, with a standard deviation of about 0.25 porosity units (p.u.) when comparing one laboratory against another. To improve reliability of routine porosity measurements, recommended practices and quality-control procedures are presented.