bluuebunny/crossref_metadata_2025 huggingface dataset:
The Open Council and Public Participation: The Leichhardt Experience
Authors: Hampton William , Pike Penelope
Published: December 2007

In 1971 an inner-city suburb of Sydney experienced a change of control following local government elections. Leichhardt, with a population of about seventy-one thousand, became one of the first local authorities in the world to have an elected council committed to the practice of citizen participation. Council meetings were thrown open to the general public who could speak, though not vote; planning for the area involved residents and neighbourhood groups stimulated by open meetings of the planning committee and by public planning discussions in each locality. Now, nearly three years later, a plan for Leichhardt has been produced and it is possible to take stock of a remarkable exercise in public participation. Despite the differences in the circumstances of local government between Australia and Britain, the Leichhardt experience, both its strengths and its weaknesses, can contribute to the discussions now taking place on the role of public participation in local planning in Britain.

As the lowest of the three tiers of government in a federal system, local authorities have a different status in Australia from that enjoyed by their counterparts in Britain. In addition, the system of local government is different in each of the six states of the Australian Commonwealth, although there are basic similarities.
Maximum likelihood estimation of the parameters of a system of stochastic differential equations that models the returns of the index of some classes of hedge funds
Authors: Fatone L. , Mariani F. , Recchioni M. C. , Zirilli F.
Published: December 2007

In this paper we study an inverse problem for a parabolic partial differential equation. The parabolic partial differential equation considered is the Fokker Planck equation associated to a system of stochastic differential equations and the inverse problem studied consists in finding from suitable data the values of the parameters that appear in the coefficients of this Fokker Planck equation. The data used in the reconstruction of the parameters are observations made at discrete times of the stochastic process solution of the system of stochastic differential equations. That is, the data of the inverse problem are a “sample” taken at discrete times of some of the components of the random vector solution of the stochastic differential equations and not, as usual, observations made on the solution of the parabolic equation. The choice of the system of stochastic differential equations and of the data used in the inverse problem are motivated by applications in mathematical finance. The stochastic differential equations presented can be used to model the dynamics of the log-returns of the index of some classes of hedge funds, such as, for example, the so called “long short equity” hedge funds and of some auxiliary variables. The solution of the inverse problem proposed is obtained through the solution of a filtering and of an estimation problem. The solution of these last two problems is based on the knowledge of the joint probability density function of the state variables of the model conditioned to the observations made and to the initial condition. This joint probability density function is solution of an initial value problem for the Kushner equation that in the circumstances considered here can be written as a sequence of initial value problems for the Fokker Planck equation associated to the system of stochastic differential equations with appropriate initial conditions. An integral representation formula for this probability density function is derived and used to develop a numerical procedure to solve the estimation problem using the maximum likelihood method. The Kushner equation provides the relation between the data and the Fokker Planck equation used to solve the inverse problem considered. The computational method proposed has been tested on synthetic data and the results obtained are presented. Some auxiliary material useful to understand this paper including some animations and some numerical experiments can be found in the website http://www.econ.univpm.it/recchioni/finance/w5. A more general reference to the work in mathematical finance of the authors and of their coauthors is the website http://www.econ.univpm.it/recchioni/finance.
Regularization by projection: Approximation theoretic aspects and distance functions
Authors: Hofmann B. , Mathé P. , Pereverzev S. V.
Published: December 2007

The authors study regularization of non-linear inverse problems by projection methods. Non-linearity is controlled by some range invariance assumption. Emphasis is on approximation theoretic properties of the discretization which determine the convergence rates. Instead of using source conditions for the true solution to represent the error, the authors show how distance functions with respect to some benchmark smoothness are able to replace this. Some examples indicate how the results can be applied.
Selected formulas of the theory of inverse problems
Authors: Anikonov Yu. E.
Published: December 2007

The work is devoted to constructive methods of investigating multi-dimensional inverse problems for evolution equations. We present formulas and relations for solutions and coefficients of evolution equations and inverse problems.
Identification of a non-convex obstacle for acoustical scattering
Authors: Nakamura G. , Yoshida K.
Published: December 2007

This paper deals with a two or three dimensional inverse scattering problem for identifying a sound hard obstacle in a homogeneous medium. We provide a reconstruction scheme for identifying the obstacle from far field patterns of scattered waves associated with incident waves in all directions when the obstacle is not necessarily convex.
Preservation Metadata: Challenge, Collaboration, and Consensus
Authors: Lavoie Brian F.
Published: December 2007

The last decade has witnessed a rising tide of digital information resources. Varian and Lyman estimate that 92 percent of the new information created in 2002 was stored in digital form on magnetic and optical media. Academia, government, and private enterprise; researchers, students, business decision-makers, and government policy-makers: all are transitioning to new models of information creation and use in digital environments.
A Failure of Imagination: The Decline of Community in a Greek Village
Authors: O'Rourke Diane
Published: December 2007

The moral and social unity of a community is not a natural association to place, but depends on the ways people frame their loyalties to place and other people, and what they imagine unites them. Benedict Anderson called the nation an imagined community. We might also call the community an imagined community. In this paper I use the case of the decline in sense of community among the inhabitants of Lehonia, Greece to illustrate how even face‐to‐face community must be imagined by its members and the way in which class divisions were able to contribute to shared local identity. Prosperity based on highly productive land and access to markets supported not only a local class system which bound together Lehonia's owners and workers, but also their sense of community. I argue that prosperity and progressiveness were integral to shared identity among those inhabitants who were members of the community. Declining returns from agriculture precipitated a decline in the salience of community in the lives of residents, and a failure of their ability to imagine themselves as a community.
Book Reviews
Authors: Kosmatopoulos Nicolas
Published: December 2007

The Disenchantment of the Orient: Expertise in Arab Affairs and the Israeli State. Gil Eyal. Stanford University Press. 2006. 336 pages. ISBN‐10 0804754039.
Book Reviews
Authors: Thornburg Aaron
Published: December 2007

The Anthropology of Ireland. Thomas M. Wilson and Hastings Donnan. Oxford: Berg. 2006. 241 pages (+ xiv). 10 1845202392 (paper).
Methods for Detection and Characterization of Reservoir Rock, Deep Basin Gas Area, Western Canada
Authors: Sneider Robert M. , King Howard R. , Hawkes H. Earl , Davis Thomas B.
Published: December 2007

Major gas reserves have been discovered in the past 5 years in Cretaceous sandstones and conglomerates at depths of 3,000 to 10,000 ft (915 to 3045 m) within Alberta and British Columbia, Canada. Discovery of these new reserves resulted from a joint geological/ petrophysical/reservoir engineering effort that utilized rock/fluid data from cuttings, cores, well logs, and drillstem and production tests. A key element in the exploration search was the rapid detection and characterization of reservoir-rock properties from well cuttings, especially of the low-permeability rocks (1 md to a few microdarcies). The methods used to establish and to characterize the reservoir potential of thick, multiple sandstone and conglomerate intervals are illustrated.

Rock studies of greater than 10,000 ft (3045 m) of conventional cores integrated with petrophysical studies of well logs and core analyses, which in turn were compared with drillstem tests (DTS's) and production tests in more than 200 wells, provide the basis for establishing reservoir rock potential. Porous rocks are subdivided into three categories.

Type I rocks are capable of gas production without natural and/or artificial fracturing.

Type II rocks are capable of gas production when interbedded with Type I rocks or with natural and/or artificial fracturing.

Type III rocks are too tight to produce at commercial rates even with natural or artificial fracturing.

Type I rocks are subdivided into four classes, with four air-permeability ranges: "A" (greater than 100 md), "B" (10 to 100 md), "C" (1 to 10 md), and "D" (+/- 0.5 to 1 md).

Criteria to identify a rock's reservoir potential from well cuttings or conventional and sidewall cores are based on examination of dry, freshly broken fragments with a binocular microscope at 20x magnification. A rock's reservoir potential is established on the basis of estimates ofsize, volume, and distribution of visible pores,particle size and distribution, andtype and amount of cements and pore-filling material and degree of consolidation (the way fragments break).

Geologists and engineers can make rapid, accurate estimates of reservoir-rock potential of unknown porous intervals with the help of a number of visual aids. These aids includeplastic trays of cuttings-size rock chips crushed from conventional cores of known rock/pore types, porosities, and permeabilities;color photographs of freshly broken surfaces of these rock/pore types taken at 20x magnification; andthin-section microphotographs and scanning electron microscope (SEM) photographs (at 100 to 5,000x magnification) of the rock chips and their pore casts.

Methods and procedures described in this paper continue to be used in western Canada as well as the U.S. for delineation of exploration opportunities, identification of bypassed pays in old wells, interpretation of well logs, and evaluation of intervals for completion.

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P. 1725^
Absolute Permeability as a Function of Confining Pressure, Pore Pressure, and Temperature
Authors: Gobran B. D. , Brigham W. E. , Ramey H. J.
Published: December 2007

This is an investigation of the absolute permeability of unconsolidated sand and consolidated sandstone cores to distilled water as a function of the temperature of the system, confining pressure on the core, and the pore pressure of the flowing fluid. The effects of flow rate and throughput are also discussed. In contrast to some previous investigations, no effect of temperature on permeability was found beyond experimental errors and effects caused by volumetric throughput. The probable causes of differing results in previous studies are also presented.
A Technique for Making High-Rate Completions in Partially Pressure-Depleted Unconsolidated Reservoirs
Authors: Trahan Glenn John , Spies Richard James
Published: December 2007

Amoco Production Co. has developed and successfully applied offshore a completion technique that has allowed high-rate completions with effective sand control in partially pressure-depleted gas reservoirs. Clean, open perforations along with a proper gravel pack design are key factors in obtaining a high-rate completion with successful sand control in unconsolidated formations. In the past, a serious problem preventing high-rate gravel pack completions in partially pressure-depleted reservoirs has been lost circulation encountered during conventional perforation cleaning-i.e.. perforation washing -before gravel packing. The technique presented in this paper is simultaneous underbalanced perforating at high perforation-shot density with a tubing-conveyed perforating gun to achieve the combination of the desired gravel pack design and clean perforations. Field data are presented to support the conclusion that no other perforation cleaning is necessary. Lost circulation during triping in and out of the hole after perforating and before and after gravel packing is controlled with a multipolymer gel pill. The field operations necessary to implement the entire technique safely are discussed in detail on the basis of offshore experience in completing wells by this method.

Introduction

With rising gas prices and improvements in well completion technology, economics are becoming more favorable for investments in reservoirs that either are currently producing or have produced in the past. If natural gas prices ar-e deregulated, the incentive for additional development in these old reservoirs will be enhanced greatly. Many of the gas reservoirs proved in the U.S. gulf coast area are contained in unconsolidated sandstones. This fact alone complicates our ability to produce this gas. When this complication is coupled with a reservoir that has been partially pressure-depleted, a completion engineer faces an especially difficult task. This paper discusses the situation in detail and presents our company's experience with high-rate gas completions and successful sand control in a partially pressure- depleted reservoir in the Gulf of Mexico.

Background

Much information and discussion appears in the literature concerning what influences a good sand control job and what influences the deliverability of a sand- controlled completion.

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P. 56^
Two-Phase Pressure Test Analysis
Authors: Bøe Arild , Skjaeveland Svein M. , Whltson Curtis H.
Published: December 2007

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

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

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

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

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

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

An 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

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

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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P. 354ˆ
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

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

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

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

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).

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p. 1366
Interfacial Light Scattering Study in Microemulsions
Authors: Kim Mahn Won , Huang John S. , Bock Jan
Published: December 2007

Thermally excited waves at the interface between two fluids contain information about the structure and tension at this interface. A surface light-scattering technique based on photon correlation spectroscopy has been developed to probe the dynamics of these interfacial waves for microemulsions. The interfacial tension (IFT) as measured by this nonperturbing technique is consistent with the values obtained by conventional methods.

We have studied the temperature and salinity dependence of σ (IFT) in a three-phase microemulsion system, and found that σ ~ ϵ2±0 5, where ϵ is the reduced variable |TC − T| and |Cc− C| with Tc and Cc representing the critical values of temperature and salinity, respectively. Furthermore, the correlation length, L, in the microemulsion phase has also been measured by dynamic light scattering. In the two-phase regions it was observed that σ~L−2, in accordance with the scaling law predictions. Thus, the scaled salinity and temperature parameters influence the IFT through their effect on the correlation length in the bulk microemulsion phase.
An Analysis of the Effect of CO2 Injection on the Recovery of In-Situ Methane From Bituminous Coal: An Experimental Simulation
Authors: Reznik A. A. , Singh P. K. , Foley W. L.
Published: December 2007

A set of experiments is described in which CO2 is injected into large cores of CH4− and water-saturated bituminous coal at elevated pressures. CO2 at pressures up to 800 psig [5516 KPa] is used to simulate the enhanced recovery of in-situ CH4 from coal beds. CO2 injection increases the recovery of CH4 by a factor of two to three times that achieved in simple desorption by pressure drawdown and atmospheric diffusion. In general, higher CO2 pressures achieve greater CH4 recovery. The presence of even small amounts of N2 in the injection gas greatly reduces the CH4 recovered. CO2 at 500 to 800 psig [3447 to 5516 kPa] is shown to be capable of completely demethanating integral coal samples. This was confirmed by tests run on crushed cores. CO2 consumption by permanent adsorption is quite high vis-à-vis the CH4 recovered and may preclude its use as an enhanced-recovery energy process. Its primary function would appear to be as a means of safely demethanating coal beds before mining.
A Critical Study of a Petroleum Engineering Computing Operation
Authors: McCarty D.G. , Welsh J.R.
Published: December 2007

During the last 5 to 10 years the application of automatic computing equipment in engineering work has developed into what appears to be a major technical development. In view of the widespread use of this type equipment, it is believed timely to examine the record critically for useful operating criteria and for clues to how productive the application of computers in engineering activities has been. In order to provide some data to assist in answering these questions, the operational history of a computing facility engaged exclusively in engineering analysis work on a service basis as part of an oil company petroleum engineering organization has, been reviewed. On the basis of this experience, an attempt has been made to point outthose procedures which have been effective in bringing about company-wide participation in the use of the equipment,how engineering development work and subsequent communication of new methods of analysis to field engineers can be accomplished, andwhat constitutes a workable procedure for producing the desired service work.

The accomplishments of this particular computing facility have been studied, and on the basis of the indicated volume of productive work and corresponding net cost, the use of general purpose digital computers in petroleum engineering activities is attractive economically. When broad participation in the use of the equipment is achieved, the communication problem associated withdistributing information on methods and the availability of specific calculation procedures to field installation,arranging for exploitation of new approaches, andmaintaining a free and reasonably simple flow channel for service work from and to field engineering groups is greatly simplified.

Introduction

The urge to enter into the present discussion of the use of automatic computers comes fromthe belief that the application of high-speed digital computers has reached the stage of development where the users can no longer expect the computers operation to be viewed as experimental, andthe fact that although a large volume of literature has appeared in recent years concerning digital computers and their use, very little information has appeared showing some of the more pertinent factors of computer operation such as unit costs, economic advantages, and other tangible benefits.

If a serious effort is made by those having experience in computer operations, it should be possible at the present time to make available sufficient information to enable prospective users to make a reasonably accurate appraisal of the potential benefits of using a computer in practically any application.
Waterflood Oil Recovery in Fractured Reservoirs With Directionally Drilled Wells
Authors: Bacon Jeffrey R. , Kempthorne Robert H.
Published: December 2007

A technique has been developed to estimate the potential effects of directionally drilled wellbore orientation on pattern waterflood oil recovery in anisotropically fractured reservoirs. The technique attempts to quantify the tradeoff between drilling directional wells either more vertically or better aligned with the major fracture orientation in situations where simple vertical wells are not possible. Among the incentives to deplete some reservoirs with directionally drilled wells are the ability to access reserves located beneath large bodies of water from shore or island structures and the economy of centralized surface facilities. The orientation of these directionally drilled wells in anisotropically fractured oil reservoirs may have a significant impact on recovery efficiency. The described method involves combining the directional permeability characteristics of the reservoir caused by fractures, drilling accuracy, and the proposed wellbore orientation to estimate the volume of reservoir that may be affected by a nonvertical well. The distribution of fractures in the reservoir, average fracture length, and effective vertical permeability are noted as being major factors influencing the effect of directionally drilled wells on oil recovery. When applied to the Norman Wells oil field (N.W. Ter., Canada), it was possible to identify elongated target areas within which any directionally drilled well is expected to have similar oil recovery.
Handling High Pressure Cycling Projects at Northwest Branch, Louisiana
Authors: Owens Herman , Kirk Earl , Brinkley T.W.
Published: December 2007

Unusually high surface injection pressures ranging from 6,500 to 6,700 psi have been required in pressure maintenance operations at Northwest Branch, Acadia Parish, La. The high injection pressures were necessary to permit cycling operations at near dew-point conditions in the condensate-bearing Nodosaria Blanpiedi No. 1 sand. Injection volumes at this high pressure have averaged 12 MMcf/D since injection started in Sept., 1955. The cycling phase of operation is approximately 65 per cent complete prior to blowdown operations. Reservoir and fluid characteristics are described and production history is presented. Performance of the cycling phase of operation is presented and is based on the original 2,100-psi separator condensate in place at start of cycling operations. Compressor operating problems are also presented.

Introduction

The Northwest Branch field, Acadia Parish, La. was discovered in Dec., 1951, and was unitized for pressure maintenance (cycling) operations on June 1, 1955. The Unit consists of the Nonion Struma No. 1 sand and the Nodosaria Blanpiedi No. 1 sand; cross faulting further defines the Unit area as Block A and Block B. Cycling operations to date include the Nodosaria Blanpiedi No. 1 sand in Block A and the Nonion Struma No. 1 in Block B. Herein is reviewed the cycling operations in the Nodosaria Blanpiedi No. 1 sand in Block A where unusually high (6,500 to 6,700 psi) surface injection pressures have been required.

Geology and Reservoir Characteristics

The condensate-bearing 11,100-ft Nodosaria Blanpiedi No. 1 sand at Northwest Branch Unit represents a productive reservoir geologically classified as closure by faulting. As illustrated in the structural interpretation (Fig. 1) the productive reservoir is bounded by faults on four sides with a limited aquifer on the structural flank.
Preliminary Report on Fracturing by Vibration - A New Method of Well Stimulation
Authors: Metzger Herbert A.
Published: December 2007

Vibration fracturing is a new method of well stimulation which may be used in either cased or uncased wells. In a cased well, the interval to be fractured is prepared by perforating the interval with a special-type vibro perforator. A specially designed explosive charge is run on a wire line and activated under a fluid column. The charge is designed to fracture the formation horizontally or weaken it so that it will take normal sand fracturing or acidizing at lower pressures. This fracturing is accomplished by setting up a large number of impulses or vibrating pressure waves along a horizontal plane. This preliminary report is designed to give the results of the use of this new method of well stimulation in various types of formation in the Texas and Mid-Continent area, and covers the time interval from February through June, 1958.

Introduction

The new fracturing technique was offered commercially in Feb., 1958. Prior to this time it had been under intensive development and field testing for nearly two years. During that period the equipment and techniques were successfully demonstrated numerous times. Since Feb., 1958, more than 300 wells have been treated with this process. The difficulties which have arisen have resulted in modifications which give every indication of solving the indicated problems. The fracturing by vibration process was developed to provide a fast, economical method of stimulating formations of low permeability, or with permeability blocks.

Description of Equipment

The complete assembly (see Fig. 1) consists of the standard electrical conductor wire line, measuring equipment, cable head, collar locator and sinker bar (where required). The special equipment used in the process includes the vibro perforator, a specially designed gun used to shoot a 1.5-in. disintegrating projectile. The 1.5-in. hole is usually shot in the center of the zone to be fractured by vibration.