bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of Multiphase Flow Functions From Displacement Experiments
Authors: Richmond P. C. , Watson A. T. 
Published: December 2007

Summary
A recently developed implicit estimation procedure (or regression-based method) that uses parameter estimation with B-spline functional representations can determine essentially unbiased estimates of relative permeability functions from dynamic displacement data. In this paper, we extend this method to estimate relative permeability simultaneously with capillary pressure functions. Careful consideration is given to the functional representation of the relative permeability and capillary pressure functions so that the most accurate estimates of these properties can be obtained. These procedures are demonstrated with laboratory dynamic displacement data.
A New Method of Continuous Thermodynamics Applied in an Equation of State
Authors: Halpin T. P. J. , Quirke Nick 
Published: December 2007

Summary
Continuous thermodynamics, in which a fluid's composition is regarded as a continuous function rather than as a set of discrete mole fractions, has been applied to petroleum fluids in a number of forms. The method provides a practical alternative to pseudocomponent methods in phase-equilibrium calculation with an equation of state (EOS). Current continuous-thermodynamic methods are limited by the functional form assumed for the composition; they are unable to retain a continuous description of all phases in the calculation while preserving material balance.
A new functional representation of continuous mixtures based on an orthonormal expansion is proposed that preserves material balance between phases and provides a versatile composition description. With such a representation, the conditions for phase equilibrium are shown to be of a simple form. Because these conditions are similar to those for a discrete composition, phase equilibrium can be calculated in much the same way. The method's accuracy approaches that of a calculation in which the composition is fully represented by a large number of discrete components. The computer time requirement, however, is far less because only a small number of terms must be retained in the expansion series. Use of this new method is demonstrated for petroleum mixtures with a modified Soave EOS.
Effects of C02 Addition to Steam on Recovery of West Sak Crude Oil
Authors: Hornbrook M. W. , Dehghani Kaveh , Qadeer Suhail , Ostermann R. D. , Ogbe D. O. 
Published: December 2007

SummaryA high-pressure ID laboratory displacement study evaluated the effects of adding CO2 to steam on the recovery of West Sak crude oil. Results of the laboratory experiments indicate that the simultaneous injection of CO2 and steam increases recovery, reduces injection temperatures, and reduces the heat input required.
A Fully Implicit Thermal Wellbore Model for Multicomponent Fluid Flows
Authors: Siu A. L. , Rozon B. J. , Li Y.-K. , Nghiem L. X. , Acteson W. H. , McCormack M. E. 
Published: December 2007

Summary
This paper describes a thermal wellbore model that simulates flow hydraulics in the wellbore and heat transfer between the wellbore fluid and the overburden. The thermal wellbore model includes the transient differential equations for multicomponent three-phase fluid flow in the wellbore and the transient heat conduction equation in the overburden. Phase behavior of the wellbore fluids is obtained from isenthalpic flash calculations, which compute the phase splits and compositions at a specified pressure and enthalpy. The wellbore and overburden equations in the entire discretization domain are solved simultaneously with a fully implicit Newton's method. The thermal wellbore model was validated with steam-injection and gas-condensate production field data. The calculated heat losses and pressure drops compared favorably with published models. The thermal wellbore model is also used to predict the critical production rate of methane above which hydrate will not form.
A Laboratory Investigation of Foam Flow in Sandstone at Elevated Pressure
Authors: Persoff Peter , Radke C. J. , Pruess Karsten , Benson S. M. , Witherspoon P. A. 
Published: December 2007

SummaryThis paper describes a study made of the flow of foam through sandstone at elevated backpressures. Gamma ray attenuation was used to measure local liquid saturations. Steady-state pressure gradients for foam were found to be essentially independent of gas velocity but nearly proportional to liquid velocity. This flow behavior of foam is explained in terms of changes in bubble texture.
Steam-Zone Electrical Characteristics for Geodiagnostic Evaluation of Steamflood Performance
Authors: Mansure A. J. , Meldau R. F. 
Published: December 2007

Summary
An essential part of the development of electrical geodiagnostic techniques for mapping thermal recovery processes is understanding the relationship of formation resistivity to the thermal recovery process. As a result of laboratory measurements of a 1D steamflood, a preliminary understanding of some of the mechanisms of the electrical resistivity change has been gained. The theory of electrical resistivity of a steamflood is reviewed and used to evaluate the resistivity changes expected. A conceptual electrical model of a steamflooded porous reservoir, based on a qualitative description of the fluid zones of an ideal heavy-oil steamflood, is presented. The model assumes that salinity, temperature, and saturation are the important factors controlling resistivity changes and that Archie's law applies. We found that the characteristics of each individual reservoir must be considered before the in-situ resistivity changes are predicted and that in-situ resistivity can either increase or decrease as a result of steamflooding.
Constant-Pressure Interference Testing: Detecting Double-Porosity Properties
Authors: Grasman T. J. , Grader A. S. 
Published: December 2007

Summary
This study presents an analytical method to determine double-porosity reservoir properties with interference pressure data in an infinite reservoir producing at constant pressure. Wellbore-storage and skin effects at production and observation wells are neglected. The effects of rD, λ, and ω on interference pressure responses are examined. For dimensionless interwell distances ≥ 100, the pressure responses are practically collapsed. As a result, a general type curve, which can be used for any value of rD, is presented that yields unique values of λ and ω for a given pressure response and rD. In addition to the log-log type curve, a semilog type curve that is more useful for pD values &gt;0.1 is presented. Semilog derivatives of the interference pressure responses are considered. The pressure derivatives enhance small variations that occur in the pressure response during the flow period affected by the double-porosity nature of the reservoir.
It is observed that for a simple correlation with λ and rD, the derivative curves for rD values &gt; 100 can be collapsed. Hence, a semilog derivative type curve is developed. This type curve has two maxima. Early- and late-time behaviors are influenced by λ. The time separation between the first and second maxima is a function of ω.
Clay Stabilization in Low-Permeability Formations
Authors: Himes R. E. , Vinson E. F. , Simon D. E. 
Published: December 2007

SummaryThe most popular clay stabilizers used recently in well-treating solutions are classified as cationic organic polymers (COP's). Recent studies have shown these stabilizers to be ineffective in microdarcy to low-millidarcy sandstones. Recent research led to the development of a stabilizer applicable to formations with permeabilities of 0.010 md and higher that also provides enhanced load-water recovery and more efficient placement from gelled-water solutions.
Analysis of Fluid-Loss Data
Authors: Clark Peter E. , Barkat Omar 
Published: December 2007

Summary
Over the last few years, fluid-loss testing has evolved from static to dynamic testing. Data analysis, however, has not progressed as rapidly as the experimental techniques used to gather the data. In this paper, various techniques of analyzing dynamic fluid-loss data are discussed and a simple, yet effective, method of describing dynamic fluid-loss curves is presented.
The analysis of dynamic fluid-loss data is usually based on the traditional square-root-of-time treatment. This type of analysis works well for static fluid-loss test data because the dynamic processes are less complex than those in dynamic situations. During a dynamic fluid-loss test, a number of different events influence the fluid loss and the shape of the fluid-loss curve. Not only filter-cake compression, but also dynamic cake deposition and cake erosion must be taken into account. In most cases, Darcy flow does not occur over the whole time span of the test.
Several complex methods of treating the data from dynamic fluid-loss tests have been suggested, but most rely on modifications of the static fluid-loss-data analysis technique. These techniques are based on the data as a function of the square root of time. With dynamic fluid-loss test data, the square-root-of-time relationship does not adequately describe the fluid-loss data. A straightforward technique to analyze dynamic fluid-loss data is discussed in this paper.
In-Situ Wettability Determination in Gas Reservoirs
Authors: Desbrandes Robert , Bassiouni Zakl 
Published: December 2007

Summary
Gas reservoirs are generally assumed to be water-wet. This is probably true in most shallow reservoirs where gas has migrated, partially replacing water in a porous and permeable trap. Gases normally do not contain impurities that are likely to alter the affinity of the grain surface for water. In deep reservoirs, oil may have been trapped first and then transformed into gas because of pressure and temperature changes. In this case, residues of bitumen and occasionally sulfur may coat the grains with a non-water-wet film. Water ganglia, then, are free in the pores, and water can flow even at a relatively low saturation.
Laboratory work has been done to define and measure the pressure profile in oil- and water-wet sandpacks at the oil/air or water/air contact. Pressure profile measurements are used to determine the free-oil or free-water level, the liquid capillary rise or fall, and fluid densities. Laboratory results show that even with the high porosity and permeability of the sandpacks, the pressure pattern at the gas/water contact is typical of rock wettability, which can be quantified. At the gas/oil contact (GOC), all sands exhibit an oil-wet behavior regardless of the wettability and residual water saturation. A field example of a pressure profile run in a gas/water transition zone is presented and interpreted in terms of wettability.
WAG May Improve Gas-Condensate Recovery
Authors: Cullick A. S. , Lu H. S. , Jones L. G. , Cohen M. F. , Watson J. P. 
Published: December 2007

Summary
This paper shows that the water-alternating-gas (WAG) process may improve sweep efficiency and gas-condensate recovery compared with continuous cycling in highly stratified reservoirs. The study used extensive numerical simulation to investigate the sensitivity of the process to several variables, including reservoir layering, permeability, relative permeability, capillary pressure, and trapped gas. The process mechanics were confirmed by laboratory displacements in layered core.
Theory of Three-Component, Three-Phase Displacement in Porous Media
Authors: Falls A. H. , Schulte W. M. 
Published: December 2007

Summary
A theory of multicomponent, multiphase displacement in porous media is further developed for three-component, three-phase systems. In regions of a tie-triangle in which one or two of the phases is (are) immobile, the description of solutions to the differential equations that govern flow is shown to be independent of the way relative permeabilities depend on saturations. When three phases flow simultaneously, key features of the mathematical solution space can be described analytically for an exponent-type relative permeability model.
Effect of Bacterial Polysaccharide Production on Formation Damage
Authors: Lappan R. E , Fogler H. S. 
Published: December 2007

Summary
In-situ growth of cellular material is known to cause formation damage. Bacterial reproduction and polysaccharide production are the key factors that segregate bacterial formation damage from fines and particulate damage. Carefully controlled experiments conducted on both high- and low-permeability ceramic cores showed that bacteria can plug the pore space and damage the cores. However, further experimentation demonstrated that polysaccharide production is largely responsible for this damage. This conclusion is based on a comparison of two experimental systems: core plugging from bacterial replication and polymeric production and plugging of the porous medium caused solely by cell division with no polysaccharide production. In light of these results, the interpretation of reservoir plugging resulting from the presence of bacteria requires further scrutiny.
Simulation of Sandstone Acidizing of a Damaged Perforation
Authors: Lea C-M. , Hill A. D. , Sepehrnoori Kamy 
Published: December 2007

SummaryA mathematical model was developed to study the effect of acidizing on the productivity of a single perforation penetrating a sandstone reservoir as a function of the distribution of damage around the perforation. Assuming the perforation to be ellipsoidal, we derived a 2D model that describes the single-phase flow of an acid through a perforated sandstone that contains two pseudochemical minerals dissolving at different rates. This paper presents cases that show the effectiveness of acidizing in removing both drilling-fluid damage and perforation damage. The most effective stimulation occurs when the perforation damage is removed by the acid.
Interpretation of Swelling/Extraction Tests
Authors: Hand John L. , Pinczewski W. Val 
Published: December 2007

SummaryThis paper describes an experimental and theoretical investigation of the relationship between the phase behavior observed in swelling/extraction tests and either slim-tube-determined minimum miscibility pressure (MMP) or critical gas enrichment. The results indicate that no simple relationship exists between the phase behavior observed in the tests and either MMP or critical gas enrichment. It is concluded that the primary value of swelling/extraction tests is that they provide phase-behavior data that can be used to calibrate equation-of-state (EOS) models, which, when used with 1D compositional simulators to model slim-tube displacements, provide realistic estimates for MMP and critical gas enrichment.
Modifying In-Situ Combustion Performance by the Use of Water-Soluble Additives
Authors: Shallcross D. C. , de los Rlos C. F. , Castanier L. M. , Brigham W. E. 
Published: December 2007

Summary
Experiments were performed to study the effects of various additives on the oxidation kinetics of Californian and Venezuelan oils. Aqueous solutions of 10 metallic salts were mixed with sand and Huntington Beach, CA, oil. The mixtures were subjected to a constant flow of air and a linear heating schedule while the effluent gases were analyzed for composition. The variation in the oxygen consumption was analyzed with a model of three competing oxidation reactions. Values for the important kinetic parameters for the three reactions were obtained for each additive. Iron and tin salts were found to enhance fuel formation, while copper, nickel, and cadmium salts had no significant effects. Other experiments with a heavy Venezuelan oil showed that, contrary to earlier suggestions, the use of a ketal did not decrease fuel formation.
New Well-Testing Pressure Functions With Applications
Authors: Onur Mustafa , Peres Alvaro M. M. , Reynolds Albert C. 
Published: December 2007

Summary
New pressure and pressure-derivative functions for analyzing well-test data are presented. The new pressure function represents the integral of pressure with respect to time divided by time. Thus, this new pressure function represents a moving or cumulative average of the pressure over time. It is shown that the logarithmic derivative of this pressure function is equal to a moving or cumulative average of the standard logarithmic pressure derivative. It also is shown that this new derivative function is useful for analyzing well-test pressure data in cases where the pointwise pressure-derivative data are difficult to interpret because of noise.
Wellbore Stress Distribution Produced by Moisture Adsorption
Authors: Yew Ching H. , Chenevert Martin E. , Wang Chein L. , Osisanya Samuel O. 
Published: December 2007

Summary
For this study, we evaluated the stress distribution produced by moisture adsorption around a wellbore by applying the mechanics of deformable solids. This paper shows that the moisture-adsorption process is governed by a diffusion equation and that the equations governing the moisture-induced stresses around the hole are similar to those equations used in thermoelasticity. A computational method is developed for calculating the stress distribution around the borehole, and the experimental procedure for obtaining the material constants needed in the computation is presented. This paper also studies the effect of borehole pressure on the stress distribution around the hole. Results show that the magnitude and distribution of stresses around the borehole are very sensitive to the adsorption characteristics and the moisture-induced modulus change of the material.
A Comparison Between Capillary Pressure Data and Saturation Exponent Obtained at Ambient Conditions and at Reservoir Conditions
Authors: Søndenå Erik , Brattell Fred , Kolltveit Krlstofer , Normann Hans P. 
Published: December 2007

Summary
The porous plate method was used to determine capillary pressure curves and saturation exponents at ambient conditions and at full reservoir conditions (reservoir pressure, temperature, and fluid) on sandstone core plugs from a North Sea reservoir. The main objective of this study is to determine whether any difference exists between the capillary pressure curves and the saturation exponents obtained at ambient conditions and those obtained at reservoir conditions for a North Sea reservoir. Results show that the capillary pressure and electrical resistivity measurements performed at ambient conditions with nonreservoir fluid displacing water can give results different from measurements performed at conditions prevailing in the reservoir.
A New Biopolymer for High-Temperature Profile Control: Part 1—Laboratory Testing
Authors: Strom E. Thomas , Paul James M. , Phelps Craig H. , Sampath Krishnaswamy 
Published: December 2007

Summary
An extracellular polysaccharide produced by Alcaligenes bacteria has been crosslinked to form firm gels that are stable for long periods at elevated temperatures. The biopolymer can be gelled with multivalent ions such as Cr+3; it can also be gelled at the 2, 000-to-4, 000-ppm level without Cr+3 in high-salinity [∼20% total dissolved solids (TDS)] brines. Gel samples have been stable for 2 years at 74 and 93°C. Gels could be formed over a wide pH range, but best long-term stability was achieved in the pH range of 7 to 8. A flow test of Alcaligenes biopolymer gel in Berea sandstone at 74 °C showed that the gel gave a brine permeability reduction factor of 320.
Improved Scleroglucan for Polymer Flooding Under Harsh Reservoir Conditions
Authors: Rivenq R. C. , Donche Alain , Nolk Christine 
Published: December 2007

SummaryPolymer flooding is commonly used to improve water sweep efficiency in oil reservoirs. Successful application of this method, however, has been restricted to low-temperature reservoirs because suitable polymers are not available for harsh conditions. Scleroglucan, a polymer produced by fermentation that shows promising properties, forms solutions that are very viscous and highly resistant to shear. Viscosity is insensitive to both salts and pH and only slightly affected by temperature. To facilitate industrial development of scleroglucan polymer, improvements in the filterability of the solutions and better knowledge of their behavior in pOrous media are necessary. A high-quality scleroglucan was obtained by eliminating the impurities responsible for polymer aggregation. This allowed evaluation of the intrinsic properties of the polymer molecules. Complete elimination of impurities from the polymer solution led to a scleroglucan without any aggregation tendency and with a good filterability, particularly at high temperatures. The performance of this improved scleroglucan in porous media was evaluated by coreflood experiments in Berea cores at temperatures ranging from 30 to 90°C. Results showed low permeability reduction and a mobility reduction close to relative viscosity. Injection of successive slugs into a Berea core under anaerobie conditions indicated low polymer retention at high temperatures (30 p.g/g at 90°C).
Features of Three-Component, Three-Phase Displacement in Porous Media
Authors: Falls A. H. , Schulte W. M. 
Published: December 2007

Summary
A theory of 1D dispersion-free displacement in porous media is used toreveal features of floods in which three phases flow simultaneously. Theanalysis shows how the sequence of compositions realized in given classes ofproblems can be recognized from a single diagram. It also explains whythree-phase routes of physical interest shock into and out of tie-triangles, why composition routes measured during relative permeability experiments oftenare identical through the three-phase region, and how an equilibrium tertiarydisplacement can evoke either an oil bank that runs ahead of the phasecontaining the active agent or one that breaks through with it.
Measurements of Supersaturation and Critical Gas Saturation
Authors: Flroozabadi Abbas , Ottesen Baard , Mikkelsen Morten 
Published: December 2007

Summary
Supersaturation and critical gas saturation were measured for two core samples with different pore structures. In these measurements, a pump with a constant rate of expansion was used to avoid steep pressure changes. Binary mixtures of C1/n-C10 at two saturation pressures were used as the fluid system. The surface tension of the binary mixtures varied from 2 to 13 dyne/cm. The data show that pore structure could significantly affect the degree of supersaturation. The supersaturation in a porous medium with small pores may be less than in a porous medium with large pores. The critical gas saturation data of this work are lower than literature values. Measurements on a chalk sample reveal critical gas saturations of about 0.5%.
Static Proppant-Settling Characteristics of Non-Newtonian Fracturing Fluids in a Large-Scale Test Model
Authors: McMechan D. E. , Shah S. N. 
Published: December 2007

SummaryLarge-scale testing of the settling behavior of proppants in fracturing fluids was conducted with a slot configuration to model realistically the conditions observed in a hydraulic fracture. The test apparatus consists of a ½ × 8-in. [1.3 ×20.3-cm] rectangular slot 14 ½ ft [4.4 m] high, faced with Plexiglas™ and equipped with pressure taps at 1-ft [0.3-m] intervals. This configuration allows both qualitative visual observations and quantitative density measurements for calculation of proppant concentrations and settling velocities. We examined uncrosslinked hydroxypropyl guar (HPG) and hydroxyethylcellulose (HEC) fluids, as well as crosslinked guar, HPG, and carboxymethyl HPG (CMHPG) systems. Sand loadings of 2 to 15 lbm/gal [240 to 1797 kg/m3] (8 to 40 vol% of solids) were tested. Experimental results were compared with the predictions of existing particle-settling models for a 40-lbm/l, 000-gal [4.8-kg/m3] HPG fluid system.