bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Sensitivity Analysis of the NPC Study of Tight Gas
Authors: Rosenberg J. I. , O'Shea Patrick , Mercer James , Morra Frank , Brashear J. P. 
Published: December 2007

ABSTRACT
In 1980, the National Petroleum Council (NPC) published the results of a two-year, multi-company study of unconventional natural gas1 It concluded that low permeability, "tight" gas reservoirs have significant potential for the U.S. domestic energy production. The size of this potential depends on the geological assessment, extraction technology performance, and production economics. The NPC assessment remains the most exhaustive and credible estimate of tight gas potential since its publication.
The Tight Gas Analysis System (TGAS) is a joint project of the Gas Research Institute and the U.S. Department of Energy. It is designed to "automate" the NPC analytical approach to tight gas assessment by creating a comprehensive model that will permit sensitivity analysis of key assumptions, updating as new data become available, and timely reinterpretation of results in light of changing technology and economics.
The TGAS model also introduces the concept of economic rent which was not explicitly reported in the NPC assessment. Economic rentis defined as the difference between the minimum required selling price for producing an incremental unit of gas (i.e., marginal cost) and current sales price. This approach assumes that all costs remain constant in real terms throughout the development of the project. This minimum required selling price is defined as that gas price (per Mcf) which equates the present value of the after-tax net cash flows from a project to zero; that is, the minimum price that fully reimburses all costs, including the risk adjusted cost of capital and taxes. Net cash flow is evaluated at the full cost of exploration and development; all transfer payments to government and royalty holders are included in this price. The reader should note that portions of this economic rent may be distributed among other participants in gas development including drillers, suppliers, royalty holders, and taxing agencies. However, if the NPC assumption that costs remain constant is retained, then economic rent is a useful index of economic attractiveness.
Determination of In-Situ Stress From Anelastic Strain Recovery Measurements of Oriented Core
Authors: Teufel L. W. 
Published: December 2007

ABSTRACT
A reliable method for determining the in situ stress state in deep formations is of great importance to the gas industry in designing massive hydraulic fracture treatments of low permeability reservoirs. Knowledge of the horizontal in situ stress directions and magnitudes would allow prediction of fracture azimuth and height. In this paper a method using anelastic strain recovery measurements of oriented core will be presented as a reliable and practical tool for determining both the directions and magnitudes of the principal horizontal in situ stresses in deep formations. The principal horizontal stress directions are determined directly from the principal horizontal strain recovery directions. The principal horizontal stress magnitudes are calculated from the principal strain recovery magnitudes, overburden stress, and Poisson's ratio of the rock using a viscoelastic model by Blanton. In addition, petrophysical measurements of the core parallel to the principal directions of strain recovery, at atmospheric pressure and at elevated confining pressure, suggest that the strain recovery process is a consequence of microcrack formation and expansion.
A New Approach for Optimizing Bit Hydraulics
Authors: Doiron H. H. , Deane J. D. 
Published: December 2007

ABSTRACT
A method is presented for optimizing roller cone bit hydraulics programs to provide minimum cost per foot drilled. The method differs from traditional optimization techniques in that optimum pump operating conditions are determined rather than being arbitrarily imposed as a constraint on the optimization process. The method considers rate of penetration (ROP) response to increased bit hydraulic horsepower (BHHP) as well as increased fuel and pump maintenance costs to provide increased BHHP. Optimum conditions may be determined through a parametric analysis or by imposing simple relationships between pump fuel and maintenance costs and ROP response to increased BHHP.
Full scale laboratory drilling data under various overbalance pressure conditions are presented to demonstrate the relationship between ROP and BHHP. Laboratory and field results with blanked nozzles and asymmetric three nozzle configurations are also presented.
Correlations for the Reservoir Fluid Properties of Alaskan Crudes
Authors: Ostermann R. D. , Ehlig-Economides C. A. , Owolabi O. O. 
Published: December 2007

ABSTRACT
Reservoir fluid properties such as bubble point pressure, formation volume factor, solution gas/oil ratio, and viscosity are required for the analysis of reservoir performance. Ideally, these properties would be determined experimentally, from laboratory PVT analyses. Frequently, these properties must be predicted in advance of PVT studies. Since the crudes from different regions have different propeties, it is prudent to assess the accuracy of the available correlations and make an informed selection for each region or type of crude.
PVT reports have been assembled from several Alaskan oil fields in the Cook Inlet Basin (CIB). The experimentally determined values for bubble point pressure, oil formation volume factor and live and dead oil viscosity have been compared to the values calculated from several popular correlations.
CIB crudes are characterized as low sulfur crudes with a high nitrogen content. Crudes from the Alaskan North Slope have high nitrogen and carbon dioxide contents. The presence of non-hydrocarbon gases has a marked influence on bubble point pressure. Correction factors must be applied.
The available correlations and corrections have been compared for application to CIB crudes, and specific recommendations for their use are included in the conclusions. The appendices to the paper also include a convenient compilation of the equations for the correlations.
The Rheological Properties of Prudhoe Bay Oil and the Effects of a Prolonged Flow Interruption on Its Flow Behavior
Authors: Economides M. J. , Chaney G. T. 
Published: December 2007

Abstract
The rheological properties of Prudhoe Bay oil, as with any other mixture of hydrocarbons, are markedly affected by the lowering of temperature. The Transalaska pipeline traversing the state in a North-South direction is subjected to severe ambient temperatures during the winter months. A prolonged flow interruption would result in inevitable heat losses from the trapped crude oil. The temperature decline would cause a significant alteration of the flow behavior. A fundamental heat transfer study and laboratory measurements were combined in order to forecast the rheological response and subsequent start-up requirements of Prudhoe Bay oil in gathering lines and in the Transalaska pipeline.
Stress-Sensitive Permeability in a High-Permeability Sandstone Reservoir—The Kuparuk Field
Authors: Adams B. H. 
Published: December 2007

ABSTRACT
Buildup test analyses for wells in the Kuparuk field, Alaska, give permeability values that are two to seven times higher than values from drawdown test analyses. Often buildup skins indicate extreme formation damage, while drawdown skins indicate minimal damage. This sandstone reservoir exhibits the characteristics of stress-sensitive permeability. Stress-sensitive permeability usually is associated with low-permeability gas reservoirs where permeability decreases as the reservoir is depleted. Although Kuparuk is a high-permeability oil reservoir, its effective permeability may drop to one-sixth of original permeability during production. Clearly, stress-sensitive permeability is not limited to low-permeability reservoirs.
The existence of stress-sensitive permeability was demonstrated using welltest analyses, simulation studies, core analyses, and laboratory flow experiments. Comparisons of buildup and drawdown test analyses first suggested this mechanism. Comparisons were made for most wells in the field, with significant differences between buildups and drawdowns evident in a majority of the analyses. Simulation of welltests required stress-sensitive permeability to match both buildup and drawdown tests. Core analyses and laboratory flowtests were done to determine the cause and magnitude of the stress-sensitive permeability.
Evidence points to open vertical fractures as the cause of this stress-sensitive permeability. These fractures are small-scale, with characteristic heights on the order of inches, and apparently randomly distributed in the reservoir. Because of the fractures' size and distribution, the reservoir behaves as a homogeneous porous medium with stress-sensitive permeability rather than as a classical naturally fractured reservoir. Welltests show no typical fractured reservoir behavior (i.e., linear flow).
The extreme effects of stress-sensitive permeability, as seen in this reservoir, can seriously impact field operations. Productivity and injectivity estimates will be incorrect if variable permeability is not recognized and incorporated in these estimates. Also, use of buildup skins calculated from constant permeability equations, such as the Horner method, to determine wellbore condition (damaged or undamaged) can lead to unnecessary and useless stimulation treatments.
Effect of Bottom Water and Gas Cap on Thermal Recovery
Authors: Ali S. M. Farouq 
Published: December 2007

Abstract
Many heavy oil formations are characterized by a bottom water sand, or a high gas saturation zone near the top. Either can have an undesirable effect on steam injection and in situ combustion response. The purpose of this paper is to present: (i) field test, (ii) laboratory model, and (iii) mathematical simulation results pertaining to bottom water or gas cap in thermal recovery processes. Some guidelines are offered for judging the suitability of a formation for one of the thermal methods.
Selected steam injection and in situ combustion projects, where a bottom water or high gas saturation zone was present, are discussed. It is shown that in a number of situations, it was possible to conduct a successful steamflood in spite of bottom water or gas zone. This was not so in some of in situ combustion projects under such conditions, where the water zone led to severe air channeling.
The laboratory model results mainly pertain to bottom water type situations in steamflooding. Results obtained by the author for tar sands, as well as those of other investigators, are discussed. A high conductivity zone near the base of the formation can serve as a means of initial heating. Subsequent steam displacement behavior would depend largely on oil viscosity and formation characteristics. One instance of a gas zone in in situ combustion is also considered.
The simulation results are those of the author, as well as other published data, concerning the effect of bottom water on cyclic steam stimulation, steamflooding, and in situ combustion response. Bottom water sand thickness is an important variable in cyclic steam stimulation, and in particular, steamflood response. In situ combustion seems to be relatively insensitive to the bottom water sand thickness, however, even small thicknesses can lead to severe air bypassing. A gas zone seems to be undesirable in the case of cyclic steaming and in situ combustion, but may be used to advantage in steam-flooding.
Persistent Action of Thin-Film Spreading Agents Used in Cyclic Steam Stimulation
Authors: Blair C. M. , Scribner R. E. , Stout C. A. 
Published: December 2007

ABSTRACT
The production histories of eight of 15 wells that received injections of a special class of interfacially active chemicals during an earlier field study have been followed during a subsequent cycle in which no chemical was used. When compared to production in the original steam-only cycle, the results show that the positive effect of the original chemical application persists into the next cycle. However, two wells, in which interfacially active agent was injected during the next cycle, gave even greater oil production.
A Rod Pumping System for California Lift Requirements
Authors: Tait H. C. 
Published: December 2007

Abstract
Artificial lift requirements in California oilfields cover a full range of demanding operating and environmental conditions. These extend from typical demands of lifting depth and volume, to atypical requirements of heavy crude, thermal enhancement and the unique environmental restrictions of our urban sites and offshore fields.
A new rod pumping system has been developed which deals with these requirements. Performance results to date confirm reduced power consumption and improved pumping performance. Combined with the compact equipment size, these characteristics appear to offer benefits to California operators.
Interaction of a Buoyant Tower with A Dynamically Positioned Drillship
Authors: Cowan Roes , Horton Edward E. , Alinaghian Yousef 
Published: December 2007

Abstract
The Buoyant Tower concept provides the means to drill for and produce oil and gas in water depths from 1,200 feet to depths in excess of 20,000 feet. The tower is freestanding and consists of a series of buoyant cylinders extending from the seafloor to within several hundred feet of the ocean surface. This concept provides a continuous buoyant column that acts as a support mechanism for extending concentric well casing and production tubing from the seafloor to well heads located at the tower top.
A unique problem associated with this long slender compliant tower is the interaction of the tower with a dynamically positioned (DP) drillship. The drillship performs several functions consisting of:
Installing the piles at the base of the tower. Drilling and completing the wells. Workover operations.
This paper addresses the feasibility of connecting a standard marine riser to the tower top from a floating DP drillship. This discussion outlines the approach to making rational predictions of the coupled ship/tower behavior and details some of the requirements necessary for conducting such an investigation.
The baseline case addressed in the discussion considers a 2,000 foot long Buoyant Tower in a water depth of 2,300 feet. The tower has a 6-well capacity with a tapered base section. The DP drilling vessel has characteristics typifying current conventional equipment. Solution methods consist of coupled rigid body and finite element models in the frequency domain.
Small Angle X-Ray Diffraction by Microemulsions
Authors: Chen Lidian , Marsden S. S. 
Published: December 2007

ABSTRACT
Microemulsion systems have been prepared by using a wide range of concentrations of either of two surfactants (TRS-10-80 or ethanolamine salt of dodecyl-o-xylene sulfonic acid (EADXS), toluene as the oleic phase and either water or dilute brines (1% or 2% NaCl) as the aqueous phase. Some were isotropic liquids but others displayed the birefringence characteristic of liquid crystals. X-ray diffraction at small Bragg angles by samples of these systems encapsulated in thin-walled, glass capillary tubes was sought and found in most systems. This usually consisted of a single ring similar to the Debye-Scherrer photographs obtained with microcrystalline powders at higher Bragg angles and had Bragg spacings corresponding to from 60 to 200 Angstrom units. For those systems having high surfactant concentration, there were generally maxima of intensity at positions perpendicular to the axis of the capillary tube suggesting orientation of larger particles or units such as those in liquid crystals.
The calculated Bragg spacings increased with a decrease in concentration of surfactant and with an increase in concentration of the toluene and/or the aqueous phase. For the systems of TRS-10-80, the presence of the NaCl at the lower concentrations had an unmeasurable effect on the x-ray diffraction but at the higher concentrations the Bragg spacings did not increase as fast. For the systems of EADXS, the presence of NaCl had no effect at either concentration on x-ray diffraction.
To a first approximation, the results can be interpreted in terms of an expanding, lamellar, hydrous liquid crystalline system in which the aqueous phase forms layers between the polar faces of bimolecular sheets of surfactant molecules and the toluene forms similar layers between the non-polar faces. The mechanism for this as well as its application to EOR is discussed in the paper.
A Synergistic Chelation System for Acidizing in the Presence of High Iron Concentrations
Authors: Ewing B. C. , Pabley A. S. , Callaway R. E. 
Published: December 2007

Abstract
A series of screening tests have been performed to determine the chemical types needed for chelating iron (Fe+++) at concentrations as high as 50,000 ppm in spent acid. The chemicals tested were liquid citric acid (LCA), nitrilotriacetate (NTA) and acetic acid (AA). A blend of liquid citric acid and nitrilotriacetate was found to be practical in a 50-50 volume blend with acetic acid added in some cases as an intensifier and pH buffer. The testing was done at room temperature (80°F, 27.7°C) and verified at 170°F (77°C). Compatibility tests and freeze-thaw tests were also run on the blend. From the data, a practical loading schedule for use in the field has been proposed.
Miscible Displacement: The Liquid - Liquid Case
Authors: Warren J.E. , Price H.S. , Skiba F.F. , Varga R.S. 
Published: December 2007

PUBLICATION RIGHTS RESERVED
This paper is to be presented at the 36th Annual Fall Meeting of the Society of Petroleum Engineers of AIME in Dallas, October 8–11, 1961, and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

Abstract
The process by which one miscible liquid displaces another liquid in a two-dimensional porous medium has been investigated by means of experimental digital computation. The effects of viscous and gravitational forces, molecular diffusion, microscopic dispersion and heterogeneous permeability have been explicitly included in the behavior equation's. A general numerical method for solving the difference analogues of the behavior equations has been developed and the occurrence of oscillatory numerical solutions has been explained.
Based on the computed results, it has been concluded that, for the viscosity function chosen, gravity segregation does not materially affect the recovery at breakthrough in a homogeneous system. It has been observed that randomly heterogeneous permeabilities cause macroscopic dispersion which tends to damp out viscous fingers; it has been suggested that viscous fingering may be a laboratory phenomenon and not a reservoir problem.

Introduction
During the last ten years, almost one hundred papers on the subject of oil recovery by miscible displacement have appeared in the literature. These papers which have covered a wide range of interests—physical principles, mathematical theory, laboratory experiments, field tests and economics—have indicated the potential importance that has been assigned to this process by the petroleum industry. Despite the concerted efforts that have been reported, the future of miscible displacement as a practical method for improving the recovery of oil remains uncertain.
Adsorption of Asphaltenes and Water on Reservoir Rock Minerals
Authors: Collins S. H. , Melrose J. C. 
Published: December 2007

Abstract
New data relating to the adsorption of asphaltenes on reservoir rock minerals are reported. The data were obtained by contacting samples of several different clay mineral types, as well as of Berea sandstone, with toluene solutions of a petroleum asphaltene fraction. This material was recovered from a deposit on the tubing string of a producing well. It was characterized with respect to molecular weight and elemental composition. Adsorption isotherms were determined and found to be of the Langmuir type, indicating monolayer adsorption. For each of the samples an independent surface area measurement was made. This permitted the probable size of the adsorbed asphaltene particles to be estimated. The effect of water on the adsorption of asphaltenes on kaolinite was also determined. It was found that adsorption was reduced but not eliminated by the presence of water. In these experiments the water was either pre-adsorbed on the clay or simply dissolved in the solvent. The amount of co-adsorbed water corresponded to 30-50 monolayers, indicating the probable formation of liquid bridges of water between clay particles. Estimates were obtained for the magnitude of the microscopic toluene/water contact angles which characterize these liquid bridges.
Noise and Vibration Control Offshore Towards an Improved Design Procedure for Topside Facilities
Authors: Venables R K , Manning C J 
Published: December 2007

Abstract
Noise and vibration control can affect the health and safety of persons employed on offshore installations in a number of ways.
Noise can be directly injurious to health; prolonged exposure to high levels of noise, or short duration exposure to very high levels, will permanently impair hearing. High levels of vibration can cause sickness and loss of balance. Both noise and vibration induce stress which is cumulative with other stresses such that, in a hazardous and demanding work environment, errors of judgement can be made and working efficiency reduced. High noise levels can also mask public address and alarm systems, and interfere with speech, telephone and radio communication. Finally, much lower levels of noise and vibration may prevent or disturb sleep and relaxation.
For these reasons, serious consideration must be given to the control of noise and vibration on offshore installations. There are now the knowledge, expertise and hardware to control satisfactorily noise and vibration in the majority of situations, but there are a number of limiting factors, including cost and engineering feasibility, and the interaction with other safety measures. The cost of noise and vibration control features, if included at the design stage, has been estimated to be from 1 to 10% of the total topside cost of an offshore installation, depending on its size and complexity. If they are initially omitted and noise and vibration have to be treated retrospectively, then this cost can easily be doubled, and engineering feasibility will limit what can be achieved.