bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Micellar Phase-Behavior Model for Simulating Systems with Up to Three Amphiphilic Species
Authors: Prouvost L. P. , Satoh T. , Sepehrnoori K. , Pope G. A. 
Published: December 2007

ABSTRACT
A thermodynamic model has been developed for the phase behavior of micellar systems containing up to three amphiphilic species. This model has been tested against experimental data using chemicals typical of those used in surfactant flooding. A fairly good match of static phase behavior experiments has been obtained. The model has been implemented in a compositional simulator and found to be both simple enough and accurate enough for practical reservoir engineering calculations. One important design is to study the separation of the chemicals as they transport through the reservoir. This type of study should be useful in selecting surfactants and cosurfactants for optimal behavior. Relatively little experimental phase behavior data are needed to estimate the parameters in the model.
The Value of 3D Seismic in Field Development
Authors: Gaarenstroom L. 
Published: December 2007

ABSTRACT
Since 3 Dimensional Seismic Surveys were introduced in the North Sea in 1976 Shell Expro has carried out ten such Surveys covering most of their fields.
The 3D seismic method is considered as a tool of growing importance for field development, especially for the marginal and economically sensistive fields. Appraisal and development drilling indicates that most fields are often more complex than originally anticipated.
Interpreted 3D seismic data available in the pre-development phase of a field's life in combination with appraisal well data could substantially support sound decisions on platform construction, drilling slots, and field development drilling.
In the example discussed, we show that an early understanding of complicated reservoir structures and structural discontinuities is a pre-requisite for optimum development of a complex structural-stratigraphic trap, such as the Cormorant Field (fig. 1).
Geological Modeling of a Heterogeneous Sandstone Reservoir: Lower Jurassic Statfjord Formation, Brent Field
Authors: Johnson H. D. , Krol D. E. 
Published: December 2007

ABSTRACT
A geological/reservoir engineering modelling study of the Brent field's Statfjord Formation reservoir is outlined as follows: (1) it describes the geological characteristics of the reservoir, (2) it illustrates how these features were incorporated into a detailed (32 layer) computer simulation model, and (3) it summarizes some of the main conclusions concerning the nature of fluid flow through this heterogeneous reservoir in relation to possible field development scenarios.
The study demonstrates how complex, three-dimensional reservoir heterogeneity can be modelled with the latest type of large-capacity computers, such as the CRAY. Since these models are geologically more realistic, they can provide a better illustration of reservoir behaviour, which will improve performance prediction.
Use of Pressure Transient Testing To Evaluate Fractured Reservoirs in Western Venezuela
Authors: Da Prat G. , Mannucci J. , Prado L. , Millan E. 
Published: December 2007

ABSTRACT
For a naturally fractured reservoir the existence of two semi-log straight lines when analysing real pressure transient data is seldom observed and some existing models for interpretation of fractured systems have always been subjected to controversy. In this study an analysis of pressure transient data taken in wells completed in fractured reservoirs in Western Venezuela has shown the existence of two well-defined parallel semilog straight lines which confirms the Warren and Root model from a practical viewpoint. The data was analysed using the type-curve corresponding to the solutions for a well with wellbore storage and skin in a reservoir with double porosity (pseudo-steady state flow). The analysis provides values for the dimensionless fractured storage parameter, ω and the dimensionless matrix-fracture permeability ratio, λ which are considered to be representative of a two-porosity system. Finally, a production forecast analysis is made for the reservoir using the obtained values of ω and λ.
Performance Testing of Well Completion Components Under Simulated Downhole Conditions
Authors: Weekers E. E. A. J. , Kastelein H. J. 
Published: December 2007

ABSTRACT
Leakage of downhole equipment can have severe operational consequences, including effects on safety, but almost invariably results in delays at significant cost.
To improve component selection on the basis of technical data and to gain more insight into the failure modes and factors involved, Shell International have built a versatile well completion component test facility.
This paper briefly describes the facility and some of the operational experiences and results gained to date in tests on premium threaded tubing/casing connections. The test procedure for tubing/casing connections that is described in the paper is largely based on the API Recommended Practice 37. Some suggestions for improving the API procedure are also presented.
Analyzing Pressure Buildup Data by the Rectangular Hyperbola Approach
Authors: Haugland T. , Larsen L. , Skjaeveland S. M. 
Published: December 2007

SUMMARY
This paper examines applicability and limitations on the use of rectangular hyperbolas to analyze pressure buildup data, with emphasis on the determination of average pressure and flow capacity. It is shown that the method can be used with confidence only if it is applied to data that can also be analyzed by conventional semilog methods, and that it for such data is essentially equivalent to the conventional methods in terms of information needed and information obtained. If we use semilog data, then we can determine the flow capacity from the slope of the hyperbola, and we can determine the average pressure indirectly from the asymptote, provided we know the drainage area and the MBH function of the reservoir. Following stabilized flow we only need the shape factor in addition to the area. If we use the direct approach, and assume that the asymptote is equal to the average pressure, then we need the same type of information to make a proper choice of interval where the hyperbola should match the buildup curve. For this direct approach we will normally get. an estimate of average pressure that is less than m/1.151 psi (kPa) above the last wellbore pressure being used in the analysis, where m is the conventional semilog slope. Moreover, if we use only semilog buildup data following pseudosteady-state flow, then we can only get an accurate estimate of average pressure by this approach if the shape factor is close to 21, or higher.
If nothing is known about the reservoir, then the hyperbola method can be used to get. a rough estimate of the average pressure, but with a high degree of uncertainty if we only have data from a short buildup period. This claim follows from the many examples included in this paper of asymptotes determined from hyperbolas matched to dimensionless synthetic buildup data plotted vs. interval midpoints.
Static Pressure Gradient Reversals in Gas Wells
Authors: Bender C. V. , Holden W. R. 
Published: December 2007

ABSTRACT
Static pressure surveys in gas wells have frequently shown a phenomenon in which pressure gradients decrease with increasing depth. Computer simulations have indicated that the main cause of these gradient reversals is reasonable temperature increases with increasing depth. To explain the pressure gradient reversals exhibited in several field examples, seven temperature distributions were incorporated in the computer model.
Evaluation of Core Damage Caused by Oil-Based Drilling and Coring Fluids
Authors: Thomas D. C. , Hsing H. , Menzie D. E. 
Published: December 2007

ABSTRACT
This paper discusses the chemical damage to cores created when oil-based coring fluids have been used in the coring operation. Changes in formation wettability and emulsification in the pores caused by oil-based fluids affect the analysis of the cores.
Two methods were used to evaluate the degree of damage to the core. First, the effective permeability to oil and to brine of a core were compared before and after injection of a drilling or coring fluid filtrate. Second, the effective permeability to oil of a core was compared before and after injection of a drilling or coring fluid filtrate at various pressure drops. Instrumentation included an ultra-speed centrifuge and permeability measurement apparatus. The experimental results indicate that the irreducible brine saturation and wettability could be changed.
Archie's m for Permeability
Authors: Hagiwara T. 
Published: December 2007

ABSTRACT
The permeability of a rock may be given by k = const, ϕm &lt;R2&gt; where ϕ, m, and &lt;R2&gt; are the porosity, Archie's "m", and the average pore throat radius squared of the rock. Or using a capillary pressure curve, we may write k = const. Sm/p2f (G) where (S, p, G) are either Thomeer or Swanson parameters.
Effect of CO2 Flooding on Dolomite Reservoir Rock, Denver Unit, Wasson (San Andres) Field, TX
Authors: Mathis R. L. , Sears S. O. 
Published: December 2007

ABSTRACT
This report documents results of a study to determine whether brine and carbon dioxide (CO2) injection significantly changes total porosity in a dolomite reservoir. Pre- and postpilot cores from closely-spaced wells in the Shell Western E&P Inc. Denver Unit CO2 pilot provided the necessary data. We concluded that only minor porosity enhancement resulted from brine dissolution of anhydrite.
Linear Stability Analysis of Immiscible Displacement Including Continuously Changing Mobility and Capillary Effects: Part II— General Basic Flow Profiles
Authors: Huang A. B. , Chikhliwala E. D. , Yortsos Y. C. 
Published: December 2007

ABSTRACT
This paper reports on the continuation of previous work1 in the linear stability or immiscible, two-phase flow displacement processes in porous media that includes continuously changing mobility and capillary effects.
In Part I simple Dasic-flow profiles that allow exact solutions to be obtained were investigated. This work uses the previous formulation in terms of eigenvalue problems to examine the stability characteristics of general basic flow profiles. hotivated by the connection between the present problem and the stability of shear layers in parallel flow2, the numerical method of "matched initial values" successfully used in the stuay of latter3 is adopted in this numerical investigation.
First, the stability of non-capillary flows corresponding to a straight line fractional flow is examined. The mathematical equivalence of these flows to miscible Displacement in the absence of diffusion is established. It is shown that such displacement is neutrally stable to small disturbances of any wavelength provided that the total mobility is continuously increasing in the direction of flow. The disp1acement is unstable to small disturbances of any wavelength if the total mobility profile contains any segment of decreasing mobility. The numerical results are in agreement with the exact solutions of part I in the limits of small and large wavenumber.
Next, the stability cf capillary fiov.-s for general basic flow profiles is examined. An analysis of the eigenvalue problem indicates the existence of a single stability curve parametrized by the viscosity ratio and relative permeability ano capillary pressure characteristics. Numerical investigations using power-law functional forms for the relative permeability show that the displacement is stable to any small disturbance provided that the viscosity ratio μoμw takes values below a critical value. The latter can toe evaluatec, fairly accurately both for arbitrarily fixed saturation end-points and the Buckley-Leverett problem, by the condition that the end-point total flow mobilities are equal.
For values of the viscosity ratio above the critical, the numerical results show that the displacement is unstable to small disturbances of wavelength larger than a critical value, and stable otherwise. This effect is attributed to the stabilizing" action of capillarity. Values of wavelength corresponding to the highest rate of growth are numerically determined. It is found that stability is enhanced at lower values of the capillary number and the injection rate. Finally, a limited sensitivity study of the effect on stability of the functional forms of relative permeability ana capillary pressure is carried out.
Rheological Characteristics of Adjustable Cross-Linked Fracturing Fluids
Authors: Royce T. N. , Beck L. M. , Rickards A. R. 
Published: December 2007

ABSTRACT
A study was done evaluating apparent viscosity and fluid stability by allowing cross-linking to occur at varying times during and after a period of high shear. A high temperature closed-loop pipe viscometer was used for this process. To observe the interdependencies of shear history, cross-linking time, and apparent viscosity, two adjustable cross-linked fracturing fluid systems were employed. As part of the study, a plexiglass parallel plate fracture and wellbore model was used to observe proppant transport for both fluid systems at ambient temperature.
Results of these studies indicate that when cross-linking time is less than the high shear duration period, both the maximum viscosity and the fluid's stability are reduced. The amount of reduction is shown to be related to the difference between the high shear duration period and the cross-link time. Also, from observations made on the plexiglassfracture model, a better understanding of the relationships among treating string residence time, cross-link time, fluid stability, and proppant transport in the vicinity of the wellbore can be developed.
Depletion Experiences and Modeling of Mixed-Porosity, Fractured, Cavernous Reservoirs in Hungary
Authors: Bálint V. , Pach F. 
Published: December 2007

ABSTRACT
Publications are relatively sparse about the analysis and modeling of mfxed porosity, fractured karstic reservoir /MPFKR/. The oil field Nagylengyel is of such type. To estimate the texture /structure/of the field some probability model was developed. By the application of the model the water driven primary depletion and the depletion by a secondary gas cap could be followed up rather well, showing results corresponding to the pilot plant and field tests.
A New Electromagnetic Propagation Tool for Well Logging
Authors: Iskander M. F. , Rattlingourd S. L. , Oomrigar J. 
Published: December 2007

ABSTRACT
The use of electromagnetic (EM) energy to evaluate rock formations and, in particular, to determine the water saturation, as well as to infer the oil and gas saturations within pores, has recently received much attention. The dielectric properties of rocks measured by these tools at microwave frequencies are strongly dependent on the water saturation and are relatively insensitive to salinity changes. Therefore, dielectric properties measurements, when used with the data obtained from other well-logging tools (e.g., those involving neutron and gamma ray densities measurements), provide valuable information that helps distinguish between hydrocarbon-bearing and water-bearing zones. The presently available EM tools are generally single frequency devices. In addition, it is difficult to design low-frequency tools of reasonable sizes and of controlled radiation patterns.
In this paper, we present a new EM tool which is based on the design of an open transmission line coupler. The main features of this tool include its broadband performance and its compact size, even down to frequencies as low as in the kHz range. It thus provides the possibilities of: Logging at various depths of investigation by varying the frequency and the separation between the couplers.The combination of low- and high-frequency measurements to separate specific dielectric parameters, such as the dc conductivity.The broadband coupling characteristics of the new coupler makes it possible, for the first time, to make swept frequency and time-domain well logging measurements.The borehole effects are minimized, since the tool is a patch-type device.
Unlike the other low-frequency EM tools, the new coupler has very well-controlled coupling characteristics, with the major part of the energy transmitted to the rock formation.
Results of our experimental evaluation of the designed tool, including measurement of the depth of investigation and the attenuation and phase shift between the transmitting and receiving couplers as a function of frequency, will be presented. It is generally shown that lower frequencies provide less attenuation and larger depth of investigation.
The tool performance is also evaluated by utilizing a computer program where the rock formation is simulated by two-dimensional cross sections with a borehole and a flushed zone of variable thickness. Results of these numerical simulations are presented. At lower frequencies, it is shown that the mud cake effects are minimized and the sensitivity of the measurements to the formation beyond the flushed zone is improved. Limitations on using planar models to evaluate the EPT performance are also discussed.
The new EM tool is capable of realizing the full potential of dielectric logging. It has the advantages of both presently available high- and low-frequency EM tools combined together. It also facilitates the unique capabilities of swept-frequency and time-domain well logging.
Deep Sucker Rod Pumping for Gas Well Unloading
Authors: Henderson L. J. 
Published: December 2007

ABSTRACT
Exxon Company, U.S.A.'s Pyote Gas Unit 14-1 in the Block 16 (Ellenburger) field became the world's deepest rod pumped well on October 7, 1983. The rod pump was installed at 16,850 ft. in an attempt to extend the productive life of the well. The artificial lift system was designed to lift wellbore fluid that was restricting the flow of gas, thus allowing the gas to be produced up the tubing-casing annulus. Implementation of the project was possible because of the recent improvements in predictive techniques, materials available for rod pumping, and industry's experience in artificial lift.
Experimental Investigation of the Performance Characteristics of Hydrocyclones
Authors: Sharma S. P. 
Published: December 2007

ABSTRACT
A mathematical model of hydrocyclone classifiers used to process drilling fluid is presented. Four basic non-dimensional parameters are defined to describe the performance of the hydrocyclones. The mathematical model is based on data acquired during a series of tests using 3", 4", 5", and 7" cones with interchangable parts. The analysis of the model indicates a non-Stokesian behavior in the classification process. According to the present findings, a Stoke-sian model tends to underdesign the hydrocyclones by at least 15-25%. Further, an optimum value of 4 × 104 for the inlet Reynolds number to the hydrocyclones has been found. A term called the "Performance Parameter," introduced in the analysis, can assist a designer to search for an optimum design through a parametric study.
Comparison of Methods for Determining In-Situ Leakoff Rate Based on Analysis with an On-Site Computer
Authors: Cooper G. D. , Nelson S. G. , Schopper M. D. 
Published: December 2007

ABSTRACT
Two methods for determining a rate of fluid loss during a fracturing treatment have been proposed. In each method, the basis for determination of the in situ leakoff rate is the downhole pressure behavior after initiating a small fracture in the zone of interest. The first method, by Nolte, utilizes a master curve fit of data derived from the pressure decline following a fracturing treatment. The second method, by Nierode, relates two or more instantaneous shut-in pressures (ISIP's) as hydraulic fracturing progresses. Nierode then calculates from the pressure changes a rate of fluid loss.
This paper discusses the analysis of downhole pressure behavior using both techniques, and direct comparisons of results are made. These studies were conducted throughout the North American continent using an on-site computer. Furthermore, limitations rarely encountered for both the Nolte and Nierode analyses are discussed. The main limitations are establishing heights for the Nolte in situ leakoff analysis and increasing pressures during the Nolte pressure decline phase. For the Nierode technique, the main limitation has been initial ISIP's higher than the final ISIP.
Combined leakoff values determined from laboratory tests and reservoir information are compared to in situ leakoff rate determinations. Specific emphasis is placed on determining the effects of natural fractures, fracture heights, and permeability on these fluid loss techniques.
Establishing the Effective Aquifer Pressure Controlling Water Drive for Gas Storage Cycles
Authors: Katz D. L. , Shah D. P. 
Published: December 2007

ABSTRACT
In water drive gas storage reservoirs, water influx and efflux rates may be determined by the simplified pseudo steady-state method. It is necessary to determine the water movement rate per unit driving force and established an appropriate distance in the aquifer from the gas reservoir at which the aquifer pressure is stable during the storage cycles. A method for this determination is demonstrated on an aquifer storage reservoir. The joining of the water movement with the p/z material balance permits a more accurate method of verifying gas inventory. This new procedure is presented to up-grade the verification of gas inventories as applied to an Illinois aquifer storage reservoir.
A New Iterative Technique With Updated Curves for Estimating Average Reservoir Pressure of Gas Wells From Buildup Tests
Authors: Toh C. H. , Farshad F. F. , LeBlanc J. L. 
Published: December 2007

ABSTRACT
The dimensionless functions used in traditional methods for estimating average gas reservoir pressure can give erroneous results, since the assumption that the product of viscosity and compressibility is essentially constant is not valid for highly compressible fluids.
In this paper a new approach, accounting for the change in the viscosity and compressibility, has been proposed for gas reservoirs. This involves the application of a perturbation technique to obtain a solution of the diffusivity equation for real gas flow in bounded systems. A set of new dimensionless functions was generated and used to estimate the average reservoir pressure by a proposed method.
The National Petroleum Council EOR Study: Thermal Processes
Authors: King J. E. , Blevins T. R. , Britton M. W. 
Published: December 2007

ABSTRACT
The EOR thermal potential of the United States has been estimated from an improved data base and individual reservoir assessment. Reservoirs with ongoing thermal projects were evaluated by means of an industry survey. Future projects were evaluated by simplified model predictions. Predictions for Implemented and Advanced Technology compare current proven practice with anticipated future technology development. For an assumed base economic case, the Implemented Technology potential is estimated at 6.5 billion barrels. The Advanced Technology potential for this case is estimated at 10.5 billion barrels. These values include oil consumed as generator fuel.