bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Phase Pressure Test Analysis
Authors: Bøe Arild , Skjaeveland Svein M. , Whltson Curtis H. 
Published: December 2007

Summary
A theoretical basis is given for well test analysis of solution-gas and gas-condensate reservoirs in the infinite-acting period. The study is limited to radial flow with a fully penetrating well in the center of the drainage area. Porosity and absolute permeability are constant, and gravitational and capillary effects are neglected. The tests are conducted at constant surface rate, and the skin factor is zero. An analytical expression for the pressure/saturation relationship is derived from the time-dependent gas and oil flow equations. This relationship can be used to generate pseudopressure functions that allow test interpretation with liquid analogy. The infinite-acting drawdown case is treated in detail, while the buildup case is briefly discussed. Theoretical developments are exemplified by simulated drawdown and buildup tests in a solution-gas-drive reservoir.
Optimization of Bit Hydraulic Configurations
Authors: Glowka Dave 
Published: December 2007

Abstract
Measurements of flow field characteristics across the face of a stud-mounted PDC bit have been obtained in a new test facility which simulates downhole flow fields. This facility and the measurement techniques employed to obtain the data are described. Flow tracer tracking and cutter heat transfer coefficient measurements are shown to be valuable in determining flow field characteristics, whereas the utility of the dye injection system tested is low. Three hydraulic configurations for the bit have been tested to determine the effects of nozzle location on bot-tomhole crossflow velocities and cutter cooling rates. The configuration that provides higher velocities and cooling rates is determined to be the one that employs smaller nozzles located near the center of the bit.
Importance of Economics in Production and Reservoir Engineering
Authors: Frick Thomas C. 
Published: December 2007

In petroleum engineering work established profitability standards must be met in the development of an oil or gas lease. To determine profitability the petroleum engineer must know the starting place and the alternates of where and how to proceed with development. Are wells to be drilled for additional reserves, or are they to be drilled for rate of production only, or both? Wider well spacing plus the early application of secondary recovery processes might be more profitable than drilling wells on close spacing. Advantage must be taken in production and mechanical engineering to minimize well and lease investment and reduce operating costs. Contractual obligations and government regulations must be followed even though they are contrary to the best engineering practices. More than likely, cash availability and the tax position of the developer will affect the timing of the development of the lease or reservoir.

Why Is It Necessary to Determine Profitability?
Profitability guides managers in most of their business decisions. However, not all engineers, not to mention managers, accountants, labor leaders and economists, can agree on how to determine profitability. Some managers like to report profitability on the basis of per cent of dollar income rather than start with investment. Walter Reuther likes to determine profitability on initial investment rather than total investment. In the oil and gas producing business one of the most popular methods of determining profitability is the investor's cash flow method. In this method we calculate the maximum rate of return at which an investor can borrow money, invest it in the proposed project, and payoff the interest and principal from the return on the project.

Defining Profits
The term profits has several meanings. One economic authority starts with what he calls gross operating profit, which is the difference between cash income and cash outgo. Gross operating profit is composed of production maintenance profits plus net profit. Production maintenance profits include wages of owners, business rent, and interest on money invested because, generally speaking, these items are costs which must be met if the business is to be carried on. The net profit is what you have left with which to pay dividends or to reinvest in the company.
Optimal Injection Strategies for the Propagation of Surfactant Mixtures Through Porous Media
Authors: Harwell Jeffrey H. , Schechter Robert S. , Wade William H. 
Published: December 2007

Abstract
The chromatographic movement of surfactant mixtures through porous media is examined to determine possible injection strategies for minimizing the amount of surfactant required in a tertiary oil recovery chemical flood. The model used does not consider the presence of oil but does account for mixed micelle formation. Expressions are derived that represent the surfactant required to expose an entire reservoir to an "effective oil recovery mixture." This effective mixture may be either one whose overall composition is within prescribed limits of the composition of the injected surfactant solution or it may be a mixture whose overall composition varies but which contains micelles of fixed composition. Mixtures considered contain cosolvents and one, two, or three surfactant components. Initial calculations neglect dispersion, but numerical calculations including dispersion leave the conclusion unchanged; within the limitations of the model, there are optimal strategies for the propagation of surfactant mixtures through porous media. The optimal injection strategy varies, depending on the nature of the surfactant solution injected into the porous medium. Conditions for and the location of the optimum are discussed. Conclusions based on observations about these systems then are extended to cover the injection of surfactant mixtures currently available commercially.
Coatings for Underground and Submerged Pipelines Operating at Elevated Temperatures
Authors: Szokolik Alex 
Published: December 2007

Abstract
The longterm corrosion protection of pipelines operating at elevated temperatures—i.e., above 122°F (50°C)—presents a unique set of difficulties. Coating-deterioration rates increase dramatically as operating temperatures increase. This paper endeavors to provide a guide for coating selection for such pipelines by defining the basic requirements, listing potential coating systems, discussing test programs, and warning of potential problems during coating application and pipe installation.
Transfer of Fluid Components in a Porous Medium at Constant Saturation and Fluid Velocity
Authors: Nielsen R.F. , Gilchrist R.L. 
Published: December 2007

Abstract
When a gas is displaced by another in a porous medium, and there is a relative immobile liquid present, there is a transition zone in which the gas composition varies from essentially that of the original gas to that of the injected gas. The change in extent of this zone with time may be governed by a mixing process in the direction of flow and by the rate of establishment of gas-liquid equilibrium, if the gases are appreciably soluble in the liquid.
The relative importance of these two factors in determining the growth of the transition zone is discussed, with appropriate equations and experimental data.

Introduction
The various solution methods of oil recovery involve a transfer of the components of a mixture, whether within a single phase or between a liquid and gas. The similarity of a natural porous medium to systems used in separation and chromatographic processes makes it seem reasonable that certain concepts used by chemical engineers in "mass transfer" might be applicable to petroleum reservoirs. One approach, the HETP (height equivalent to a theoretical plate), involves a distance or length of time over which equilibrium might be considered as established. Another approach involves direct use of a rate of mixing or rate of establishment of equilibrium. The latter approach has been preferred in relation to production problems.

Discussion and Procedure
When a gas or liquid in a porous medium is displaced by one of different composition but miscible with it there will be set up a transition zone in which the composition varies from essentially that of the original fluid to essentially that of the injected fluid. If the fluid being displaced is a gas, and there is a relatively immobile liquid present, the transition zone may be defined such that the liquid ahead of and behind this zone is practically in equilibrium with the original and injected gas, respectively. It is the extent of the transition zone which is of primary interest, for, if this is relatively small compared to the whole system approximate recovery calculations can be made purely by an over-all material balance and, if two phases are involved, by equilibrium considerations.
Multigrid Solution of the Pressure Equation in Reservoir Simulation
Authors: Behie Alda , Forsyth Peter A. 
Published: December 2007

Abstract
The multigrid technique is compared with the incomplete Cholesky conjugate gradient/modified incomplete Cholesky gradient (ICCG/M1CCG) methods for solving implicit pressure, explicit saturation (IMPES)-type pressure equations. The numerical results of several test problems with widely varying transmissibilities are presented.
The multigrid algorithm is enhanced by pattern relaxation and acceleration. Optimization of the ICCG/MICCG algorithms is investigated by high-order (up to tenth) decompositions and different ordering schemes. For large problems the multigrid method is superior in terms of scalar work. The multigrid scheme can also be highly vectorized, and is an O(N) algorithm even for problems with large jump discontinuities in equation coefficients.
Results of the multigrid method applied to nonsymmetric problems are also presented.
Benchmarking a Sparse Elimination Routine on the Cyber 205 and the Cray 1-S
Authors: Woo P. T. , Levesque John M. 
Published: December 2007

AbstractAn existing general sparse-elimination algorithm was benchmarked on the Cyber 205 and the Cray 1-S. Computation rates on the Cyber 205 reached 16.7 million floating point operations per second (MFLOPS) and 9.8 MFLOFS on the Cray 1-S. It is concluded that the existing algorithm does not exploit the full potential of the vector computer. Several schemes are under investigation to improve the performance of the algorithm.
Adsorption/Desorption of Sulfonates by Reservoir Rock Minerals in Solutions of Varying Sulfonate Concentrations
Authors: Somasundaran P. , Hanna H. Shafick 
Published: December 2007

Abstract
In micellar flooding, reservoir rocks are exposed to surfactant solutions of varying concentrations as the surfactant slug advances through the reservoir. Therefore, the attachment and detachment of sulfonates with rocks that are already exposed to surfactant solutions of higher or lower concentrations is of major interest. In this study, the abstraction behavior of purified Na-dodecylbenzene-sulfonate on Na-kaolinite by stepwise increase in surfactant concentration is determined. Deabstraction* occurring after reductions in surfactant concentrations at various stages also is determined. Most importantly, the results of incremental abstraction, individual abstraction, and deabstraction showed the system to exhibit hysteresis or memory effects. Also, abstractions obtained at various pH values and during stepwise changes in pH exhibited marked differences.
The deabstraction isotherms showed the presence of maximum in certain cases, indicating the occurrence of maximum on the abstraction isotherms to be a real phenomenon. Possible reasons for the hysteresis are considered, and the practical implications of these memory effects on micellar flooding and depletion experiments using cores are discussed.
Oil Production From Reservoirs With an Oil Layer Between Gas and Bottom Water in the Same Sand
Authors: Van Lookeren J. 
Published: December 2007

Abstract
In the case of a reservoir where the oil underlies a large gas cap and overlies bottom water, production can be improved considerably if wells are perforated below the water-oil contact rather than opposite the oil-bearing section. The theoretical arguments for this improvement, which in some cases may be tenfold, are supported by experimental evidence.
Introduction
Reservoirs frequently consist of one sand body containing an oil layer underlying a thick, gas-bearing section and overlying bottom water (Fig. 1). Wells in such reservoirs are customarily opened up opposite the oil-bearing interval or, rather, opposite the lower part of this interval (Fig. 2).
More often than not, it is inefficient or prohibited to blow off large quantities of gas with the oil. This imposes a severe limitation on the drawdown, which results in low oil-production rates. Because of the small difference in specific gravity between oil and water, the latter will easily cone upwards, so that the production of water together with the oil is not prevented by this completion method.
In such a situation wells should be opened deeper, in the originally water-bearing zone. The gas can be shut off by not perforating over the upper part of the interval (Fig. 3 or by a tubing hung close to the bottom of the interval (Fig. 4). Initially much water will be produced. but when steady-state conditions have been established (as depicted in Figs. 3 and 4) larger drawdowns are permissible than in a conventionally completed well, and correspondingly higher oil-production rates will result. Water cuts are only slightly higher because of the small effect of gravity on the water-oil flow distribution.
CALCULATIONS
The ratio of improvement has been estimated by means of approximate calculations. The completion depicted in Fig. 4 is the most convenient basis for these calculations. By postulating that vertical flow gradients can be disregarded, the Appendix shows that the well-known Dupuit formula can be obtained except for some complication due to the presence of two fluids rather than one. The Appendix makes the reasonable assumption that, for suitable boundary conditions, the oil layer occupies a constant fraction of the total fluid height throughout the reservoir. The oil- and water-production rates can thus be related to the liquid levels in the borehole as follows:
(1)
(2)
In a conventional completion the minimum fluid level in the borehole may be taken as the original oil-water contact, thus limiting the oil-production rate to
(3)
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Are We Making Water Systems Too Complex?
Authors: Bilhartz H.L. 
Published: December 2007

Introduction
This paper focuses attention on several widely publicized but questionable production practices. For expediency, conclusions and opinions are given without supporting data or case history detail. These opinions were formed in the course of engineering studies on approximately 200 water floods. While this departure from ordinary literary construction may limit scientific value, it permits wider coverage, hence a broader perspective.
While the views presented may differ from many found in the literature, there is no intent to belittle the work of past authors, whose contributions to science and the oil industry are recognized. These facts, however, do not prevent the present reappraisal of ideas even though some have become well established.
One reason for questioning existing waterflood concepts is to combat complexity. Water handling systems are becoming too complicated. The literature will testify to the existence of this trend; virtually every article proclaims the necessity of complicated plants. So many prejudices and misconceptions have arisen that simple solutions found in ordinary operating techniques are being lost in the mire of complication. Plants are becoming complex and expensive. So-called water treating is approaching a state of impossible execution in an oil field. The economic influence of minor problems is being greatly exaggerated. Expensive chemicals are being added to water with little thought to their over-all effect. It is rare that the need for treatment is proved before it is used. Rarer still is a sound evaluation of its effect. Is this complexity necessary? On the contrary, historical evidence points to the opposite conclusion. Complicated systems have led generally to poor-quality operation. Chemical additives used without discretion have caused as many problems as they have cured.
In-Situ Combustion in Naturally Fractured Heavy Oil Reservoirs
Authors: Schulte William M. , de Vries Arnold S. 
Published: December 2007

Abstract
In fractured reservoirs primary production of heavy oil is mainly from fractures (secondary porosity). Matrix oil can be produced only at a very low rate because of low oil mobility. In this paper, in-situ combustion is considered as an EOR method.
Experiments are described which show that the burning process is governed by diffusion of oxygen from the fractures into the matrix. The main oil-production mechanisms were found to be thermal expansion and evaporation with subsequent condensation of the oil from the matrix.
A semi-two-dimensional (2D) numerical simulator has been constructed for modeling the process. It incorporates the main physical mechanisms as found in the experiments; heat losses to cap or base rock and gravitational effects are not included. The model predicts that in-situ combustion in fractured reservoirs is feasible and will have a high recovery efficiency in the swept zone. Oxygen breakthrough was observed when the air-injection rate exceeded a critical value predominantly determined by the fracture spacing.
This phenomenon and also the shape and width of the combustion zone can be explained by a simple analytical model, which is in fair agreement with the simulator results. The effect of heat losses on the velocity of the combustion front is estimated and a lower bound for the injection rate can be obtained in this way. Combining this lower bound with the upper bound for oxgen breakthrough leads to a maximum value for fracture spacing. This distance will be on the order of 1 m [3.28 ft]. The conclusion is that in-situ combustion appears to be a feasible process in a naturally fractured reservoir with a high recovery in the swept zone. However, for predictions for a particular reservoir, vertical sweep efficiency should be taken into account.
Equilibrium of a Microemulsion That Coexists With Oil or Brine
Authors: Huh Chun 
Published: December 2007

Abstract
When salinity, or an equivalent variable, is increased, microemulsions generally undergo orderly transitions from a lower- to middle- to upper-phase. Even though the Significance of such multiphase behavior has been well recognized in the design of surfactant flood processes, their quantitative nature in terms of the molecular structures of the surfactant lipophile, hydrophile, and the oil and brine salinity has not been fully understood. A theory of lower- and upper-phase microemulsions that gives reasonable predictions of their interfacial tensions (IFT's) and phase behavior is presented. In the theory, the Surfactant monomers adsorbed at oil/brine interface cause the interface to bend as a result of an imbalance between the hydrophile/brine interaction on the one hand and lipophile/oil interaction on the other. With sufficient imbalance, high local curvature causes small drops of one phase to disperse into the other. In addition, interactions between these drops are taken into account for the microemulsion equilibrium. The theory also offers a possibility of being able to describe the hydrophile/lipophile-balanced state (optimal salinity state of Healy and Reed1) in terms of the tendency of surfactant layer at the oil/brine interface to bend.
Well Pressure Behavior of a Naturally Fractured Reservoir
Authors: Streltsova Tatiana D. 
Published: December 2007

Abstract
The pressure response pattern of a naturally fractured reservoir is considered under the assumption allowing matrix-to-fracture crossflow to result from a diffusion mechanism of fluid transfer through the matrix. The transitional pressure during time-variant crossflow is shown to develop on a semilog plot a linear segment with a slope equal to one-half that of the early- and late-time pressure segments. For a single well, this allows use of a conventional Horner-type analysis.
Unsteady-State Pressure Response Due to Production With a Slotted Liner Completion
Authors: Spivak David , Horne Roland N. 
Published: December 2007

Summary
The transient behaviour of production from a well with a slotted liner has been solved analytically by the source function method. The unsteady-state pressure response was examined as a function of slot frequency and slot pressure response was examined as a function of slot frequency and slot length, with a penetration ratio of 1:2. The results indicate that limited entry into the well causes skin effects. However, the effects become negligible when three or more slots are distributed around the circumference of the liner. For more than three slots, the well effectively behaves like a continuous-surface cylindrical source (or a line source well, depending on time and location). We conclude that there is likely to be little reduction in flow efficiency in an ideal slotted liner completion, unless some slots are clogged.

Introduction
A well is completed with a slotted liner when sand problems occur, mainly in unconsolidated formations. The slotted liner is a preperforated tubing. Usually, the slots are milled and machined in vertical rows, parallel to the axis of the pipe. The most common patterns of slot arrangement are staggered vertical, multiple staggered vertical, and horizontal (Fig. 1). Standard spacing of slots is 6 in. between the slots in each vertical row, while their length is usually 1 1/2 to 2 in., depending on their width. The common practice is to specify two rows for each inch of nominal pipe diameter. An analytical solution to the problem of transient pressure response due to production through a liner with staggered vertical rows of slots was found. The technique used was the source function method suggested by Gringarten and Ramey. It applies the use of a line source of finite length that in turn represents one of the systems of slots. The solution technique was verified by comparison with the continuous-surface cylinder solution in the case of a large number of vertical rows of slots. No storage or damaged zone effects were considered.
Problem Description Problem Description Consider an infinite, homogeneous, and isotropic porous medium. The transient (unsteady-state) flow of a slightly compressible fluid is governed by the diffusivity equation
............................(1)
where = is the diffusivity term. The solution to a particular problem is determined by the initial and boundary conditions. One of the problem is determined by the initial and boundary conditions. One of the most well-known solutions is Kelvin's instantaneous point source function,
............................(2)
Eq. 2 represents the pressure drop created at Point M in a reservoir of infinite extent by an instantaneous point source of strength q at Point P, distance d from Point M (Fig. 2).
JPT
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