bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slug-Test Analysis in Double-Porosity Reservoirs
Authors: Grader Abraham S. , Ramey Henry J. 
Published: December 2007

Summary
The pressure response of a double-porosity reservoir to a slug test in a fully penetrating well with wellbore storage and skin is presented. Pseudosteady-state matrix flow and transient matrix flow with and without matrix skin are considered. Three kinds of type curves are discussed: early-time log-log, intermediate-time semilog, and late-time log-log. Pressure distribution around the active well and the prospects of interference slug testing are considered.
The early-time response of the slug test depends on the presence of wellbore skin; hence, two kinds of early-time type curves are presented. When the active well has wellbore skin, the early-time correlating parameter is the product of the skin and the dimensionless storage, resulting in a new log-log type curve. When wellbore skin is not present, the early-time response is proportional to the square root of time with dimensionless storage as the correlating parameter. The intermediate-time semilog type curves are applicable when wellbore skin is not present, or CDe2S&gt;104. The double-porosity effects are significant in the late-time log-log format, but the flat portion of the pressure response occurs at dimensionless pressures less than 0.01.
The radius of investigation of the slug test in a double-porosity system is also examined with and without wellbore skin at the active well. Interference responses and pressure profiles are presented. Although the presence of wellbore skin reduces the magnitude of the dimensionless pressure responses at observation wells, the detectable radius of investigation does not significantly depend on wellbore skin. Interference slug testing in a double-porosity system requires high-precision pressure-recording tools in the observation wells because the double-porosity effects occur at small dimensionless pressures.
Transient matrix flow without matrix skin reduces the double-porosity effects and limits the use of type curves for determining λ and ω. The slug-test double-porosity effects in a reservoir with transient matrix flow with fracture skin and pseudosteady-state matrix flow are similar.
Effect of Dipping Beds on the Response of Induction Tools
Authors: Anderson Barbara , Safinya Kambiz Ali , Habashy Tarek 
Published: December 2007

Summary
This paper describes a computer model for studying the effect of dipping beds on the response of induction tools. Simulated tool response in an arbitrary number of dipping beds is obtained from calculations of the magnetic fields of an equivalent magnetic dipole with an axis arbitrarily oriented with respect to the direction of stratification. The effects of the borehole and the invaded zone are neglected to solve the problem in a closed form.
In addition to describing the model, we also study the effect of dip angle on the apparent resistivity and the apparent bed thickness as read by induction tools in several typical logging configurations.
The Quarantine Bay 4RC CO2 WAG Pilot Projects: A Postflood Evaluation
Authors: Hsie J. C. , Stephen Moore J. 
Published: December 2007

Summary
This paper reviews the design, implementation, and performance of a miscible CO2 water-alternating-gas (WAG) project in a U.S. gulf coast reservoir. The field-test data obtained since the inception of the project in Oct. 1981 are presented, and solutions to such operational problems as downhole corrosion are discussed. Remarkable project response and recovery demonstrated that the CO2 WAG process is technically viable for mobilizing considerable amounts of residual oil from watered-out Miocene reservoirs. A 16.9% recovery of original oil in place (OOIP) was obtained with a CO2 slug size of 18.9% original HCPV. The CO2 requirement was 2.57 Mcf/bbl [458 m3/m3] of oil recovered.
A Laboratory and Field Evaluation of the CO2 Huff ’n’ Puff Process for Light-Oil Recovery
Authors: Monger T. G. , Coma J. M. 
Published: December 2007

Summary
Cyclic CO2 injection for enhanced recovery of light crude oil is investigated. Results from watered-out Berea corefloods and 14 field tests demonstrate that first and second cycles recover waterflood residual oil. Factors that may improve performance include larger reservoir slug volume, soak period, thicker interval, and lower prior water cut.
Interpretation of Pressure-Buildup Responses in Gas-Condensate Wells
Authors: Jones J. R. , Vo D. T. , Raghavan R. 
Published: December 2007

Summary
Methods to analyze buildup responses in gas-condensate reservoirs producing below the dewpoint pressure are examined. Two analogs to compute formation flow capacity and average reservoir pressure are presented. These analogs are based on the steady-state theory (developed by O'Dell and Miller and later modified by Fussell) and the single-phase-flow theory (which ignores the existence of the two phases). The mechanical skin factor can be computed from the derivative response by computing the appropriate dimensionless pseudopressure.
A Method for Analyzing Pulse Tests Considering Wellbore Storage and Skin Effects
Authors: Dinges Darrell D. , Ogbe David O. 
Published: December 2007

Summary
Pulse testing is used to determine the transmissivity and storativity of a reservoir. A pulse test is conducted by creating a series of flow-rate changes at an active (pulsing) well and observing the pressure response at a nearby observation (responding) well.
Previous studies have shown that wellbore storage and skin effects should be accounted for when analyzing a pulse test. This study presents the data required for the analysis and design of pulse tests considering wellbore storage and skin effects at the pulsing or responding well, for tests run with unequal producing and shut-in periods. Before this study, data were limited to tests run with equal producing and shut-in periods. The use of unequal producing and shut-in periods is necessary to optimize test design and analysis. To reduce the amount of data required in this method, a new correlation is used and a set of regression coefficients is provided. A field example is included to illustrate how to use this method.
Investigation of Foam Stability in Porous Media at Elevated Temperatures
Authors: Isaacs E. Eddy , McCarthy F. Clare , Maunder J. Darol 
Published: December 2007

SummaryThis paper describes a laboratory study of the factors controlling the formation and breakdown of foams in porous media at elevated temperatures. The degradation of a foam when gas injection was discontinued involved the gradual transformation of a foam with a noncondensable gas phase (gas foam) to a foam with steam as the gas phase (steam foam). The ability to prevent release of the noncondensable gas phase was strongly influenced by surfactant type and concentration. The formation of steam foams in the absence of noncondensable gas was a critical function of steam velocity and permeability. Surfactant concentration and chain length, salinity, and the presence of oil were important variables in determining mobility reduction of steam. Increased oil recovery from cores undergoing steam displacement was obtained when surfactant slugs were injected with and without noncondensable gas. The presence of a noncondensable gas led to the formation of a more effective and durable foam.
Low-Temperature Oxidation of Viscous Crude Oils
Authors: Fasslhl Mohammed R. , Meyers Kevin O. , Baslle P. F. 
Published: December 2007

Summary
During in-situ combustion, oxygen can bypass the flame front and react with oil temperatures that are relatively low compared with those in combustion. These reactions, called low-temperature oxidation (LTO), can adversely affect the crude's physical and chemical properties and result in lower oil recovery. This paper presents laboratory study results on the LTO of four oils, ranging from 31.1 to 10.1° API and from 14 to 54, 300 cp dead-oil viscosity at 85°F. They include two biodegraded oils, a mature crude, and an immature heavy oil. The LTO of these oils is reported as a function of reaction time, oxygen partial pressure, and temperature. LTO increased oil viscosity and density. For the 31.1 °API oil, these increases are minor and should have insignificant effects on process performance. For the heavier oils, however, the viscosity of the oxidized oils increases exponentially with increasing extent of oxidation, XO2 Relatively minor oxidation (40 mgO2/g oil) results in a six-fold increase in viscosity. The rate of viscosity increase depends on an oil's API gravity, origin, and composition.
Compositional changes accompanying LTO are also discussed. LTO is shown to increase the asphaltene content of the oxidized oils significantly, and a correlation is presented between asphaltene content and XO2 Simulated distillation results demonstrate that LTO does not significantly affect the volatility or carbon number distributions of either the light or heavy oils. The observed physical and compositional property changes are consistent with the LTO mechanism proposed in the literature: oils → resins → asphaltenes/coke.
Molecular Degradation, Injectivity, and Elastic Properties of Polymer Solutions
Authors: Southwick J. G. , Manke C. W. 
Published: December 2007

Summary
New features of polymer rheology in porous media were observed when hydrolyzed Polyacrylamide (HPAM) solutions were flowed through sandstone, gravel packs, and glass-bead packs at high rates. Independent measurement of elongational viscosity, µe, with a ductless-siphon technique demonstrates that the enhanced resistance seen at high flow rates is not directly proportional to µe. Furthermore, significant permeability trends in resistance factor and mechanical degradation are observed when plotted vs. strain rate. When these results are translated to field flow rates and geometries, they indicate that HPAM solutions can be injected at reasonable injection pressures with minimal viscosity losses, provided that perforated completions are designed with either sufficient perforation density or perforation size.
The Coefficient of Isothermal Compressibility of Black Oils at Pressures Below the Bubblepoint
Authors: McCain William D. , Rollins John B. , Lanzi Alejandro J. Villena 
Published: December 2007

Summary
Values of oil compressibility are required in all solutions of transient fluid-flow problems. Oil compressibility can be calculated directly if reservoir-fluid studies are available. In this paper, empirical equations are presented to provide accurate estimates of the compressibility of black oil at pressures below the bubblepoint when laboratory measurements are not available.
The equations were developed with data from reservoir-fluid studies of 260 oil fields worldwide. The data encompassed a wide range of oil compressibilities, surface-gas specific gravities, stock-tank oil gravities, solution GOR's, reservoir pressures, reservoir temperatures, and bubblepoint pressures
Effect of Drilling Fluids on Rock Surface Properties
Authors: Cuiec L. 
Published: December 2007

Summary
This paper discusses the wettability change induced by contact between porous media and drilling fluids and the possibility of eliminating such alterations by cleaning. Three porous media were studied (sandstone, shaly sandstone, and carbonate), as well as various drilling fluids (oil- and water-based). Initially strongly water-wet (hydrophilic) and initially neutral rock/oil/brine systems were evaluated. Wettability was estimated by a test based on spontaneous and forced displacement experiments.
The results show that all the oil-based drilling fluids used induce a wettability change inasmuch as the rock is initially water-wet. The rock surface properties are observed to be affected at a distance &gt; 0.6 in. [&gt; 1.5 cm] from the rock/drilling-fluid interface. Cleaning procedures with toluene and methanol circulations can return the rock surface to the original wettability state, but the permeability remains affected. Water-based drilling fluids made no appreciable change in the wettability of the three initially highly hydrophilic porous media.
Oil Recovery by Gravity Segregation
Authors: Richardson J.G. , Sangree J.B. , Sneider R.M. 
Published: December 2007

Technology Today Series articles provide useful summary informationon both classic and emerging concepts in petroleum engineering. Purpose: To provide the general reader with a basic understanding of a significantconcept, technique, or development within a specific area of technology.
Gravity segregation of oil from gas- or water-invaded regions is anefficient natural recovery mechanism if conditions are favorable. Favorableconditions include high vertical permeability, an advantageous relation betweenrelative permeability and oil saturation, high vertical continuity, a largedensity difference, low oil viscosity, and long oil drainage times after aregion has been invaded. Recoveries as high as 87% of the original oil in place(OOIP) have been observed in gas-invaded regions of the Hawkins field and morethan 80% OOIP has been recovered from water-invaded parts of the East Texasfield.
Theory for calculating the vertical segregation of oil first was presentedby Cardwell and Parsons in 1949. Equations were derived from Darcy's law andthe continuity equation, assuming that the driving force for oil movement isthe hydrostatic head caused by density differences. Thus, the theory firstassumes that pressure gradients caused by movement of the displaced fluid, gasor water, is negligibly small. This is usually valid, especially at low oilsaturations. The second tacit assumption is that capillary pressure gradientscaused by saturation gradients are small. Calculations show that ignoringcapillary pressure gradients usually results in errors in the average oilsaturation of less than 1% PV because capillary pressure gradients becomesignificant only as the equilibrium saturation distribution above the gas/oilcontact (GOC) or water/oil contact is approached.
Computation of the Pseudoskin Factor Caused by a Restricted-Entry Well Completed in a Multilayer Reservoir
Authors: Yeh N. , Reynolds A. C. 
Published: December 2007

Summary
This work considers flow to a restricted-entry well in a single- or multilayer reservoir where crossflow occurs between reservoir layers. A simple algebraic expression for approximating the pseudoskin factor caused by restricted entry is presented. It is shown that, for practical purposes, this equation yields sufficiently accurate estimates of the pseudoskin factor regardless of the location of the open interval. This work also extends single-layer results of interest in well testing to the multilayer case and shows that if sufficient data are available, the results of this work can be used to prepare a complete analysis of well testing pressure data obtained at a restricted-entry well.
Critical Rate for Water Coning: Correlation and Analytical Solution
Authors: Høyland Leif A. , Papatzacos Paul , Skjaeveland Svein M. 
Published: December 2007

SummaryTwo methods are presented for predicting critical oil rate for bottomwater coning in anisotropic, homogeneous formations with the well completed from the top of the formation. The first method is based on an analytical solution where Muskat's assumption of uniform flux at the wellbore has been replaced by that of an infinitely conductive wellbore. The potential distribution in the oil zone, however, is assumed unperturbed by the water cone. The method is derived from a general solution of the time-dependent diffusivity equation for compressible, single-phase flow in the steady-state limit. We show that very little difference exists between our solution and Muskat's. The deviation from simulation results is caused by the cone influence on potential distribution.The second method is based on a large number of simulation runs with a general numerical reservoir model, with more than 50 critical rates determined. The results are combined in an equation for the isotropic case and in a single diagram for the anisotropic case. The correlation is valid for dimensionless radii between 0.5 and 50 and shows a rapid change in critical rate for values below five. Within the accuracy of numerical modeling results, Wheatley's theory is shown to predict the correct critical rates closely for all well penetrations in the dimensionless radius range from 2 to 50.
Gas Supply and Requirements in California
Authors: Bradfield S.A. 
Published: December 2007

To understand properly the gas supply and demand situation in California one significant fact must be kept in mind: To the California householder, gas is the universal fuel. He looks to the state's gas utility companies to supply him with fuel for househeating, cooking and water heating, and to a somewhat lesser extent, refrigeration. His dependence on gas is traditional since California, unlike many other parts of the country, does not have major coal deposits.
California's cities are young, almost as young as the petroleum industry which supplies them with natural gas. The major portion of the state's growth has taken place since the turn of the century, particularly in the more populous southern half. The two world wars, the intervening period of boom and depression, and the post-World War II period have seen an unprecedented population increase and the development of an enormous west coast industrial empire. Fuel for both domestic and industrial growth has been supplied almost exclusively by the expanding petroleum industry through equally expanding facilities of the state's gas utility companies. To tell the story of the growth in California's gas requirements is the prime purpose of this paper.

Increase in Requirements
California's modern history is the story of many booms, but it was not until the first World War that its major industrialization and attendant domestic growth began. In 1920, the beginning of Southern California's greatest period of development, the state's population was 3,426,861. During the ensuing 30 years, population more than tripled to a present total of 10,586,223.
The most rapid increase in population has occurred in the southern portion of the state, including Los Angeles and contiguous territory. The 14 counties comprising the southern half of California have increased in population from 1,512,839 in 1920 to 6,095,394 in 1950.
Though the increase in California's population has been rapid, the use of natural gas has more than kept pace. In 1935 there were 1,486,640 general service customers in the state who consumed 71,638,340 Mcf of gas. In 1950, there were 2,880,180 who used 249,315,565 Mcf, an increase in the number of customers of 93 per cent but an increase in gas consumption of 248 per cent. Obviously, the increased number of gas users does not tell the whole story of the firm gas load increase.
To further illustrate the increased gas usage by California householders, the average general service customer in Southern California used about 83 Mcf of gas during the relatively cold year of 1949.
Physical Deliverability of Gas Reserves
Authors: Gardescu Ionel I. 
Published: December 2007

Introduction
The rate at which oil and gas can be produced over the life of a field is of major importance in ascertaining the purchase value of a property, the security of a loan, or the assurance of a steady supply of oil and gas to a pipeline. This paper deals only with the problem of predicting the future production of gas wells.
The deliverability study presented is an illustration of a workable method of estimating the volume of gas-well gas available under certain conditions of field performance, contractual obligations and other physical and regulatory limitations. The study is based on exhibits and accompanying supporting data prepared for and submitted to the Federal Power Commission in a recent Certificate Case of Public Convenience and Necessity.
In connection with the estimation of gas reserves, two general terms are being used which, to avoid confusion, should be defined.
Recoverable reserves are estimates made of the ultimate volume of gas that can be produced profitably from a reservoir. In general, there is no restriction imposed as to the period over which the gas will be recovered or the rate of flow that has to be maintained.
Deliverable reserves are estimates made of the volume of gas that a reservoir or well can deliver during a given period of time, at a specified contractual rate of flow, against a certain wellhead pressure, under the prevailing physical conditions of the gas reservoir and the status of well development in the field, taking also into account any other contractual and applicable regulatory restrictions.
One of the main factors involved in the estimate of delivery is the computation of "physical deliverability" which shows the maximum rate at which a well can be produced under the existing characteristics of the reservoirs and lease operations. Thus, the physical deliverability is a ceiling beyond which a well or reservoir cannot be produced under given conditions. However, other restrictions may further curtail the rate of delivery below the estimated maximum physical deliverability volume.
Viscoelasticity of Crosslinked Fracturing Fluids and Proppant Transport
Authors: Acharya A. Ruma 
Published: December 2007

SummaryIn hydraulic fracturing treatments, the success of the treatment strongly depends on the proper placement of proppant particles in the fracture. "Proper placement" means the packing of the fracture to achieve maximum conductivity of gas/oil through the fracture into the wellbore. The placement of the proppants along the fracture is based on design equations where sand transport velocity is related to the rheological parameters of the fracturing fluid and characteristics of the proppant particle, such as size and density.The present work describes the theoretical transport equations that take into account the elasticity of the fluid in predicting proppant settling rate in the fracture. It presents the rheological data of commonly used fracturing fluids (titanate and borate crosslinked), including viscous and elastic parameter measurements made with a Rheometrics Pressure Rheometer™ (RPR) and Rheometrics Mechanical Spectrometer™ (RMS-800). These data show some important differences between borate crosslinked gels and titanate crosslinked gels. The paper also presents experimental data of proppant settling rates in various fracturing fluids and how these can be correlated with rheological parameters obtained in this work. The difference in rheology between borate and titanate gels was correlated with the difference in settling rates of proppants in these two gels. The theoretical and experimental work presented here led to the conclusion that the model for proppant placement in a hydraulic fracture should include: (1) proppant characteristics, (2) viscous rheological parameters (K and n), (3) elastic parameters (complex dynamic viscosity) from linear viscoelastic constitutive equation, and (4) normal stress difference from nonlinear viscoelastic constitutive equation. The influence of crosslinked-polymer-gel network structure on proppant transport is also discussed.