bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure Transient Testing of Methane Producing Coalbeds
Authors: Kamal M. M. , Six J. L. 
Published: June 2014

SUMMARY
A new analysis method for pressure transient testing in coal degasification projects is presented. The results from this method show that transient testing can be used to characterize methane producing coalbeds. Formation permeability, reservoir pressure, and wellbore skin can be calculated using the proposed method. Use of conventional single phase analysis produces different results.
The current practice calls for testing coalbeds by a series of water pump-in and falloff tests upon completing the wells to ensure a single phase system. Once gas production starts, a multi-phase system raises serious concerns about the validity of conventional pressure transient analysis in coal degasification projects. However, testing of methane producing coalbeds is important because in addition to the need of monitoring the pressure and wellbore conditions, the cleat system permeability may change as the pressure is decreased.
Therefore, a new analysis method has been developed for these systems. The method is based on a pseudo pressure function that uses the adsorption isotherm and relative permeability relations of the reservoir. The method enables the interpretation engineer to calculate the absolute permeability at any time even when both gas and water are being produced. The method was verified by successfully analyzing simulated tests from a rigorous coal degasification numerical simulator. The method was then used on field buildup data taken shortly after gas production began from a well. The same absolute permeability was calculated as that from the water pump-in and falloff tests which were run in the same well upon its completion. Results from field tests on another well also are included in the paper.
Analysis of Steady-state, Vapor-Liquid Concurrent Flow
Authors: Parlar M. , Zeybek M. , Yortsos Y. C. 
Published: June 2014

ABSTRACT
Steady-state methods are commonly used for the determination of the relative permeabilities of single component vapor-liquid systems, such as steam-water. Even though such experiments are performed under adiabatic conditions, the interpretation of results has proved to be difficult. Reasons involve phase change, heat transfer, capillarity and rate considerations.
This paper presents a systematic study of the saturation and temperature distributions in steady-state, vapor-liquid flows and examines their sensitivity to parameters such as injection rate, permeability and core length. Two sets are analyzed, one pertaining to the simultaneous injection of a two-phase mixture (Sanchez and Schechter, 1987) and another involving phase change (liquid to vapor) within the core (Miller, 1951). End effects and, in general, effects associated with capillary heterogeneity are also analyzed.
Solution trajectories in the temperature-saturation plane are constructed. They allow a unified approach to the two problems (two-phase or single-phase injection), which are shown to lie on different parts of the same trajectory. Minimum conditions for the development of in-situ evaporation are developed. Then, the process sensitivity to parameter values is examined for steady-state two-phase injection and relative permeability estimation. It is found that a plateau region develops, within which the inlet saturation is approximately constant, although corresponding saturation profiles are not necessarily flat. Numerical estimates show that the estimation error involved increases with decreasing enthalpy and decreasing permeability.
A Laboratory Investigation of Viscosified CO2 Process
Authors: Bae J. H. , Irani C. A. 
Published: June 2014

ABSTRACT
Supercritical CO2 was thickened using a commercial silicon polymer and toluene as cosolvent. The pressure range for polymer solubility in CO2 was determined, and the viscosity of the thickened CO2 measured. The viscosified CO2, increased by two orders of magnitude in viscosity, was used in corefloods in Berea and carbonate reservoir cores. The oil recovery obtained with the viscous CO2 was compared with the results obtained using neat CO2, WAG(1:1), and CO2 with a cosolvent without a polymer. The results show clearly that oil recovery is enhanced and CO2 breakthrough retarded significantly with viscosified CO2.
Evaluation of the High-Speed Centrifuge Technique for Determining Capillary Pressure at Low Wetting-Phase Saturations
Authors: Melrose J. C. , Mallinson J. E. 
Published: June 2014

ABSTRACTRecent experimental studies of the high-speed centrifuge technique have indicated that the method, if properly used, yields results which are in accordance with other methods. These studies have also shown that the concept of an irreducible wetting phase saturation is not valid. In the present paper work is reported in which these previously presented results are extended to both higher and lower capillary pressures. Air/liquid data have been obtained with n-decane as the wetting phase and are compared with new data (as well as with the previously reported data) for the air/brine system. The study involved 242 days of centrifugation and utilized 10 different Berea plug samples and 5 different high permeability plug samples taken from a producing reservoir.The linear relationship between log Pc and log &lt;Sw&gt; (or log Sw, as observed in previous work) was confirmed for Berea samples over the average saturation range from about 30 percent down to 10 percent. For lower average saturations, the saturation data are not sufficiently precise either to (1) demonstrate conclusively the persistence of this relationship, or (2) prove the breakdown of the Hassler boundary condition. For three of the five producing reservoir samples, it was found that two different linear segments characterized the log Pc versus log &lt;Sw&gt; relationship, with a rather sharp transition occurring in the 30 to 40 percent average saturation range.
Chemical Properties of Chromium/Polyacrylamide Gels
Authors: Lockhart Thomas P. 
Published: June 2014

SUMMARY
Experimental studies on aqueous Cr+3/polyacrylamide (HPAAm) gels have led to new insight into their structure and chemical properties. In particular, Cr+3 is shown to form molecular crosslinking complexes with HPAAm, and to display chemical reactivity typical of inorganic coordination complexes. On the basis of ligand-induced de-gelation reactions, a new hypothesis regarding the bonding between HPAAm and Cr+3 is formulated. Comparisons are made between the chemistry of HPAAm gels prepared with chromium acetate complexes and those with inorganic Cr+3.
Spectrophotometric Determination of Acrylamide Polymers by Flow Injection Analysis
Authors: Taylor Kevin C. 
Published: June 2014

SUMMARY
Flow injection analysis has been applied to the analysis of acrylamide polymers to provide an automated determination at the rate of 90 samples/hour. The method is suitable for use with acrylamide polymer samples obtained from enhanced oil recovery operations, given a constant degree of polymer hydrolysis. An N-bromo amide is formed, which subsequently oxidizes iodide to iodine. Iodine is measured spectrophotometrically as the starch-triiodide complex. The method is applicable in the range of 0.5 to 75 mg/L polyacrylamide. Relative standard deviation of less than 1.5% was obtained. Detection limit (S/N=3) is 0.2 mg/L. The problems of a non-zero intercept and surfactant interference, which occur in the manual starch-triiodide method, were corrected.
Vectorízation and Parallel Processing of Models with Local Grid Refinement
Authors: Quandalle Ph. , Moriano S. 
Published: June 2014

ABSTRACT
This paper discusses the vectorization and parallel processing of numerical simulation using discretization grids with completely flexible grid cell connections.
Until now, local grid refinement has been considered as an obstacle to the efficient vectorization of reservoir simulation models. Highly vectorized codes have long been available for models which have a regular underlying discretization grid, ie. with no local grid refinement, no faults, and no pinchouts, and the same discretization scheme is used all over the grid. These codes exhibit a large speed up between their execution in scalar and vector modes. However, when the same codes are adapted to handle irregular matrix structures, their high performances on vector processors drop dramatically. In this case, the inner loops of the calculation kernel are indexed on the number of neighbours a given cell has rather than the overall number of cells. This is why the corresponding codes have a poor degree of vectorization. To get better performances, a greater transformation of the codes is necessary.
To the best of our knowledge, this is the first paper to describe how a reservoir equation solver, which accounts for local grid refinement, has been restructured to facilitate vectorization and parallel processing. This solver uses the ORTHOMIN procedure [1], and the BSOR method (Block Successive Over Relaxation) [2] as préconditionner. The result is a general code which runs on vector processors with about the same efficiency whether or not the underlying grid includes local refinement. Based on explicit to fully implicit, black-oil and compositional simulations, the speed up of the linear equation solver, due to vectorization, ranges between 5 and 9, depending on the simulation and the vector computer. The performances are thus comparable to those of a more specific code specially designed for regular grids.
LPG Storage at Mont Belvieu, Texas: A Case History
Authors: Ratigan J. L. , Vogt T. J. 
Published: June 2014

Summary
The Barbers Hill salt dome contains 124 solution-mined, liquified-petroleum-gas (LPG) storage wells with a capacity of 200 × 106 bbl. A geomechanics evaluation of the facility is described that includes mechanical testing of salt and caprock core, structural evaluation of the storage and brine disposal wells, and development of a subsidence evaluation network.
Optimal Control of Steamflooding
Authors: Liu Wei , Ramirez W. Fred , Qi Yu Feng 
Published: June 2014

SUMMARY
A system science approach using optimal control theory of distributed parameter systems has been developed to determine operating strategies that maximize the economic attractiveness of the steamflooding processes. Necessary conditions of optimization are established by using the calculus of variations and Pontryagin's Maximum Principle. The objective criterion is to maximize the difference between oil revenue and injected steam cost. A stable and efficient numerical algorithm is developed.
The performance of this approach is investigated through various two–dimensional steamflooding problems. The effects of reservoir properties and heterogeneity on optimal policies as well as the sensitivity of the control variables are studied.
Results show this method yields significant insight into the steamflooding process. The improvement of economic objective is significant under optimal operation.
Optimization of Well Rates under Gas Coning Conditions
Authors: Urbanczyk Christopher H. , Wattenbarger R. A. 
Published: June 2014

SUMMARYThis paper develops a method for optimizing well rates when wells are coning gas and field rates are constrained. Since each well's GOR depends on its rate, then well rates must be individually specified. This method maximizes field oil rate when gas rate is fixed and minimizes field gas rate when oil rate is fixed. The method can be used for (1) field operation, (2) reservoir simulation forecasting, or (3) simple material balance applications (as shown in the paper).
The Simultaneous Measurement of Interfacial Tension and Oil Viscosity at Reservoir Conditions for Prudhoe Bay Fluids by Surface Laser Light Scattering Spectroscopy
Authors: Dorshow Richard B. 
Published: June 2014

SUMMARY
Surface laser light scattering spectroscopy is a well-suited method for the measurement of crude oil/hydrocarbon gas interfacial tension and crude oil viscosity at elevated pressures and temperatures. The results reported herein are the first measurements of these properties in crude oil/gas systems at reservoir conditions using surface laser light scattering, and are the first reported measurements of interfacial tension for Prudhoe Bay fluids at reservoir conditions.
Water Flooding of Gas Condensate Fluids in Cores Above and Below the Dew-Point
Authors: Henderson G. D. , Danesh Ali , Peden J. M. 
Published: June 2014

SUMMARY
Water-wet cores saturated with gas condensate were flooded with water above and below the dew-point at different rates and pressure levels. The rates of gas, condensate and water recovery, and the residual saturation of fluids have been measured and the results are presented. The conclusions are relevant to the overall management of gas condensate reservoirs.
The Application of Simulated Annealing to Stochastic Reservoir Modeling
Authors: Deutsch Clayton V. , Journel Andre G. 
Published: June 2014

SUMMARYStochastic reservoir models must honor as much data as possible to be reliable numerical models of the reservoir under study. Traditional stochastic modeling techniques are ill-suited to reproduce complex geological/morphological patterns. The simulated annealing technique offers promise as a complementary tool to incorporate such information.
Corrosion Problems Associated with the Use of Copper-Based Corrosion Inhibitor Intensifier in Acid Stimulation Treatments
Authors: do Carmo Marques Luiz Carlos , Mainier Fernando B. 
Published: June 2014

SUMMARY
The results of a laboratory study carried out to investigate copper deposition and localized corrosion on API N-80 carbon steel are presented. Hydrochloric acid-based stimulation fluids and a recovered worn-out acid sample from the field were used in the tests. To all the tested fluids a copper-based corrosion inhibitor intensifier was added. The tests performed, which also included Scanning Electronic Microscopy and X-rays Fluorescence analysis, showed that the galvanic corrosion promoted by copper deposition on steel is evident and the corrosion process caused by the recovered worn-out acid might be severe.
A Model to Design the Foam Cement Job
Authors: Martins André Leibsohn , Campos Wellington 
Published: June 2014

SUMMARYFoam cement is a well proved technique to perform cementing jobs across weak or fractured formation without losing circulation. This work reviews basic aspects of the technique and presents a mathematical model, based on static calculations, for planning purposes. The use of the model enables the performance of a sensibility analisys of the parameters involved. An optimum design requires careful planning of ideal number of fluids to be foamed, gas nature, number of stages, density of base slurry and use of backpressure.
A New Model for Pressure Transient Analysis in Stress Sensitive Naturally Fractured Reservoirs
Authors: Celis V. , Silva R. , Ramones M. , Guerra J. , Da Prat G. 
Published: June 2014

ABSTRACT
The most commonly used methods to describe the transient flow behavior in porous media are based on the assumption of constant rock properties. Nevertheless, these methods are not strictly applicable to reservoirs that undergo changes in the rock properties due to variation in pore pressure. A frequent characteristic of fractured reservoirs is sensitivity of permeability and porosity to effective stress.
This paper presents a new analytical model, for interpreting pressure transient test. The model considers the flow in a naturally fractured stress sensitive reservoir, that is to say, the dependency of rock properties on pressure is established (dependency of permeability on pore pressure is measured by the permeability modulus parameter), and makes that the flow equation be strongly non linear. Likewise, the theory is developed under unsteady- state or pseudosteady-state conditions, and considers that the fracture is uniformly distributed, matrix geometry is the so called stratum and flow contribution from the matrix to the fracture is described by the term source proposed by De Swaan.
The problem stated is solved through an analytical approach for different boundary conditions and different permeability modulus values, thus obtaining type curves that can be used for the analysis of pressure buildup and drawdown tests.
Capillary Pressure, Water Relative Permeability, Electrical Conductivity and Capillary Dispersion Coefficient of Fractal Porous Media at Low Wetting Phase Saturations
Authors: Toledo Pedro G. , Novy Robert A. , Davis H. Ted , Scriven L. E. 
Published: June 2014

SUMMARY
Transport properties are critical for many reservoir engineering calculations. This work describes recent progress in modeling transport properties of natural porous media at low saturations of a wetting phase, i.e. when total wetting phase saturation Sw is the sum of thin-films and pendular structures inventories. Capillary pressure Pc, wetting phase relative permeability krw, electrical conductivity σw, and capillary dispersion coefficient Dc have been observed to obey power laws in the wetting phase saturation. We relate power-law behavior at low wetting phase saturations, i.e. at high capillary pressures, to the thin-film physics of the wetting phase and the fractal character of the pore space of natural porous media. If wetting phase inventory is primarily pendular structures, and if thin films control the hydraulic resistance of wetting phase we deduce the power laws X=SwbX, with X = Pc, krw, σw and Dc, where for capillary pressure bPc=−1/3−D, for wetting phase relative permeability bkrw=3/m3−D, for electrical conductivity bσw=1/m3−D, and for capillary dispersion coefficient bDc=3−m4−D/m3−D, where m is the exponent in the relation of disjoining pressure and film thickness and D is the fractal dimension of the surface between the pore space and grains or matrix. Recent experimental work lends support to these scaling laws in the cases of natural sandstones and clayey soils. Recent displacement experiments show anomalously rapid spreading of wetting liquid during imbibition into a prewet porous medium. We explain this phenomenon, called hyperdispersion, as viscous flow along fractal pore walls in thin films of thickness h governed by disjoining forces and capillarity.
Reservoir Engineering Study of CO2 Enhanced Oil Recovery for the Nipa 100 Field, Venezuela
Authors: Almeida Jaime , Espinoza Carlos , Mosquera José , Todd Michael R. 
Published: June 2014

SUMMARY
The J2L interval in the NIP-103 reservoir is comprised of a thin, uniform, high permeability sandstone. Well spacing is about 120 acres/well in the miscible-flood target region. The well configuration is non uniform. Oil saturation in the miscible flood target area is expected to be near initial at the start of CO2 injection. These characteristic distinguish this application from the majority of existing miscible floods.
In order to study the interaction of the CO2 miscible flood process with the J2L reservoir characterization, a numerical simulation study was conducted. First, a set of one dimensional simulations was made in order to examine linear displacement features. Then, multi-dimensional pattern flood simulations were conducted. Finally, a numerical simulation of the J2L CO2 pilot project was undertaken. This part of the simulation work included the construction of a field model, calibration of the field model through history-matching previous field performance, and examination of the CO2 miscible flood process as it might be implemented in the J2L.
Modeling and Optimization of Plunger Lift Assisted Intermittent Gas Lift Installations
Authors: Chacín J. , Schmidt Z. , Doty D. 
Published: June 2014

ABSTRACT
A novel mechanistic model for the design of plunger assisted intermittent gas lift installations is presented. The model considers the complete production cycle: accumulation of reservoir fluids in the wellbore, annulus pressure build-up, plunger/liquid slug rise, liquid production into flowline. It is based on the fundamental mass balance and conservation of momentum equations and considers all important parameters: reservoir pressure, inflow performance, tubing and flowline characteristics, plunger characteristics, available injection pressure, surface injection choke design, gas lift valve design and performance, etc.
The model solution requires numerical techniques, and it is implemented as a computer program for personal computers and mainframe workstations. One of the most innovative characteristics of the model is that it incorporates, as part of the dynamic numerical simulation, experimental plunger rise data relating instantaneous plunger velocity to instantaneous liquid slippage past the plunger. As a result, liquid "fallback"losses can be estimated and need not be assumed.
The model and computer program has been verified and validated both qualitatively and with field data. Comparisons of model predictions versus field data are included. To the best of the authors knowledge, this the first published work in which a full model of this type of artificial lift installation is undertaken.
Finally, it is shown how the model can be used to obtain an optimum design of a new installation, considering both gas consumption costs and crude recovery. Furthermore, examples are included to show how to use the program to effectively optimize existing installations.
The Role of Pressure Transient Analysis in Reservoir Characterization - An Integrated Approach
Authors: Alvarado Ramón W. 
Published: June 2014

SUMMARY
Most reservoirs exhibit complex variations of sand continuity, thickness, structural patterns, and pore space attributes (permeability, porosity, and capillary pressure properties). The most effective way to identify and quantify rock framework and pore-space variations, is through the deliberate and integrated use of engineering and earth-science technology. The development of the pressure derivative technique of well test interpretation, has greatly improve the identification of features that are often not evident on a Horner plot. This paper illustrates, with several field cases, how an adequate model of the reservoir can be diagnosed by complementing the transient response analysis, based on the pressure derivative method, with the existing geological, openhole, core analysis and performance data.