bluuebunny/crossref_metadata_2025 huggingface dataset:
Produced-Water Treatment Technology— A Study of Oil/Water Separation in Gravity-Type Crossflow Pack Separators for Qualitative Separation
Authors: Kenawy F. A. , Kandil M. E. , Fouad M. A. , Aboarab T. W.
Published: December 2007

To handle ever-increasing oily water volumes and to improve water quality discharge, separation equipment should be developed to meet industry demand and match environmental regulations. However, special constraints such as size, simplicity of operation, variable fluids, different operating conditions, and economics warrant special emphasis. Therefore, the study of traditional gravity-type oil/water separation equipment is essential to enhance the separation process and maximize its effectiveness. This will become increasingly important as environmental regulations become more stringent in the future. This paper, trying to meet this target, presents a modified design for the standard crossflow pack (CFP) separator. The new added development to the design of the separator incorporates a mechanism whose function will be forwarded to provide a shaking motion to its stationary plate pack. This mode of operation has the potential to improve oil/water separation, minimize the plugging tendency of the plates, and consequently maximize the effectiveness of the crossflow pack separator.

The obtained results revealed that the effectiveness of the cross-flow pack separator had been increased because of the shaking of its plate pack, and it reached its peak value at the flow Reynolds number (based on the hydraulic diameter as the characteristic length) equivalent to 1,830. On average, the CFP separator removed all oil particles greater than 30 ßm for streams whose oil-in-water concentration was greater than 150 ppm.

Therefore, it can be demonstrated that providing a shaking motion to the traditional CFP separator has an appreciable potential to improve oil/water separation. Continuing research is encouraged, to ensure the establishment and achievment of proper scientific criteria for the CFP separator.
Collapse Pressure of Coiled Tubing Under Axial Tension
Authors: Yang Yong S.
Published: December 2007

As the coiled tubing is cycled on and off the reel and over the gooseneck, initially nearly perfectly round CT becomes oval. This ovality significantly decreases the collapse failure pressure as compared to perfectly round tubing. An analytical model of collapse pressure for oval tubing under tension load is developed based on elastic instability theory and the von Mises criterion. The theoretical model shows satisfactory agreement with experimental data for 3.5" OD and 0.190" wall thickness tubes with small ovality.
The Effect of Fluid Flow on Coiled-Tubing Reach
Authors: Bhalla Kenneth , Walton I. C.
Published: December 2007

A critical parameter for the success of many coiled-tubing (CT) operations in highly deviated or horizontal wells is the depth penetration that can be attained before the CT buckles and locks up. Achieving a desired depth is always critical in CT operations, and attaining an additional reach of a few hundred feet can be crucial. This paper addresses the effect of fluid flow in the CT and in the CT/wellbore annulus on the state of force and stress in the CT, and thereby predicts its effect on the reach attainable by the CT.

The flow of fluid through the CT and the annulus between the CT and the borehole modifies the pressures and the effective force that govern the mechanical stability of the CT. The net force per unit length caused by fluid flow in the CT and annulus between the CT and casing/well is calculated in terms of the shear stress, and its effect on the onset of buckling and lockup is determined. A model is then implemented in a full-tubing-forces calculation, and the effect of flowing fluids and producing fluids on reach is analyzed. The new model is used in desiging commercial jobs.

The exact analytic model shows that fluid flow inside the CT has zero impact on reach, that downward flow in the annulus has a favorable impact, and that upward flow in the annulus reduces the maximum attainable reach.

A CT job can be designed using the full-tubing-forces model, taking into account the flow of a fluid with a specified rheology, density, and flow rate. Thus, the feasibility of attaining a given reach can be more accurately determined. Results are presented in the form of the surface weight for commercial wells and are compared to field jobs.
Measurement of Oil and Water Flow Rates in a Horizontal Well With Chemical Markers and a Pulsed-Neutron Tool
Authors: Roscoe B. A. , Lenn C. P. , Jones T. G. J. , Whittaker A. C.
Published: December 2007

A new approach to obtaining oil and water flow rates in producing horizontal wells has been developed with a pulsed-neutron tool (PNT). This approach uses separate measurements of oil and water velocities in combination with separate holdup measurements to obtain the flow rates.

The velocity measurement uses water-soluble and oil-soluble chemical markers, both of which are insoluble in the other fluid phase for the measurement. The markers are injected into the borehole by a logging tool at one location and detected by a PNT at a second location. The transit time between injection and detection of the marker gives a measurement of the fluid velocity. Because the markers are soluble in only one phase, the velocity of each phase can be measured separately. This measurement has been made under both laboratory and field conditions to measure velocities from 10 to 500 ft/min at horizontal and several degrees deviation from horizontal. The results of these tests show good linearity and repeatability of the measurement.

The holdup measurement is performed with the inelastic data from a PNT. With these data, it is possible to obtain quantitatively the holdup of all three phases by combining information from the inelastic near/far (N/F) ratio with the near and far carbon/oxygen (C/O) ratios. This approach to the holdup measurement has been demonstrated by use of a combination of laboratory data, Monte Carlo modeling, and field data. The results of this study have demonstrated that the root-mean-square (RMS) accuracy of this measurement is about 6% on each of the three phases.
Hydrocarbon Management—Surface Processing Facilities in the Prudhoe Bay Field of Alaska
Authors: Chambers M. J. , Eager K. D. , Mattison S. A.
Published: December 2007

Facility debottlenecking and corrosion/erosion repairs are costly penalties being paid today for previous design decisions. These decisions were made without correctly anticipating long-term changes in the field production profile. This manuscript addresses specific problems at the F-Pad production facility, located in the western operating area of the Prudhoe Bay field on the north slope of Alaska. These problems resulted from a lack of long-term planning on prior well-pad-expansion projects. This manuscript addresses present problems and impacts, current fixes and lessons learned, proposed solutions and benefits, and forward-looking designs.

Past facility-expansion projects on F-Pad have proved to be a liability today. Short-term economic decisions made during low-oil-price environments in the past have caused corrosion/erosion problems and introduced high surface flowing pressures as the production trends of the wells on the pad changed. Two major facility-debottlenecking projects have been required to address these problems and to accommodate new well additions to the pad. Many patches, repairs, and flowline swaps have also been required. A post-mortem of the completed debottlenecking Phase One project will be provided, including descriptions of the problem, solution, scope of work, expected cost and benefits, and measured benefits. The lessons learned will be presented in the form of the proposed debottlenecking Phase Two plans and the best design options for future new well expansion of well pads in the Prudhoe Bay field.

Information provided in this manuscript can lead directly to better long-term planning for production-well-facility-expansion projects. Longer-term thinking can prevent building-in limitations that cannot handle changing production trends, that can reduce facility life because of corrosion/erosion conditions, and that may prevent value-added future expansion projects.
The Effect of Sulfur Deposition on Gaswell Inflow Performance
Authors: Roberts Bruce E.
Published: December 2007

Deposition of solid elemental sulfur in the formation may significantly reduce the inflow performance of sour-gas wells. The key operational and reservoir parameters that influence the magnitude of impairment by sulfur deposition were identified through the derivation of an analytical expression for the rate of sulfur buildup assuming idealized flow conditions. A methodology for the use of conventional, black-oil reservoir simulators was subsequently developed to permit the investigation of sulfur-deposition processes for specific reservoir descriptions and well operations. The rate of sulfur buildup in the formation was shown to be inversely proportional to the square of the radial distance from the well. As a consequence, the magnitude of sulfur deposition is highly sensitive to well skin— the lower the skin, the farther away from the well the deposition occurs and the lower the sulfur-buildup rate. Nonuniform deposition over the pay interval (owing to reservoir layering or uneven stimulation) was shown to accelerate the impact of sulfur deposition. A field case involving early decline in well production caused by sulfur deposition was successfully history-matched with the simulation model developed in this study.
Popeye Project: An Overview
Authors: McLaughlin D. C. , Alford B. J.
Published: December 2007

This paper presents an overview of the Shell Offshore Inc. (SOI) Popeye project, a remote subsea gas development in 2,040 ft of water in the Gulf of Mexico (Refs. 1 through 4 contain additional technical details on the project). Planning and execution of the project required a balance throughout between proven methods, cost reduction, requirement for extending technology, and the desire to develop a system which could be used as a stepping stone to future deepwater prospects. Popeye was successfully installed and started up in January 1996. It represents application of an innovative, yet cost-effective, field development system that advanced the state of deep-water subsea technology.
A Pore-Level Investigation of Relative Permeability Hysteresis in Water-Wet Systems
Authors: Dixit A. B. , McDougall S. R. , Sorbie K. S.
Published: December 2007

Oil-recovery efficiency is known to depend crucially upon the surface chemistry of the particular crude oil/brine/rock system under investigation. Mineralogy, brine chemistry/pH, crude-oil composition, and ageing conditions all serve to modify the effective contact angles operating within a mixed-wet, porous medium. Recent network-modeling studies have helped to clarify the important role played by wettability during multiphase flow in nonuniformly wet systems. The consequences of modified-contact angles during waterflooding have been described in terms of various regimes. These have, subsequently, been used to reconcile a wide range of apparently contradictory wettability experiments.

The purpose of this paper is to apply these ideas to the study of hysteresis phenomena in both strongly and weakly water-wet, drainage/imbibition, relative permeability curves. Such hysteresis effects have long been recognized, but the precise direction of hysteresis seems to vary from study to study. Indeed, in water-wet media, even the degree of sample consolidation appears to play an important role.

A three-dimensional (3D) network model is reported, which takes into account a great deal of the underlying pore-scale physics. Initial water saturation, wettability alterations, film flow, phase trapping, and realistic variations in advancing and receding contact angles are all incorporated into the simulations.

More specifically, this study examines relative permeability hysteresis in systems from Regime IA, which corresponds to strongly and weakly water-wet, porous media (i.e., media where some degree of modification in the distribution of effective contact angles has occurred). The consequences of different combinations of pore-scale-displacement mechanisms (viz., snap-off and piston-like displacement) for relative permeability hysteresis has been calculated by means of the pore-scale simulator. The effects of combining these mixed mechanisms with other network properties, such as coordination number (z) and certain volume and conductivity exponents (ν and λ), are also reported. The nature of hysteresis is found to change quite dramatically as these parameters are varied, and all experimentally observed trends in relative permeability hysteresis are reproduced under suitable conditions. This may be the first time that a pore-scale model has been used to provide a clear interpretation of all experimentally observed hysteresis trends during primary drainage (PD), secondary imbibition (SI), and secondary drainage (SD) displacements in both strongly and weakly water-wet systems.
A New Interpretation Model for Fracture-Callbration Treatments
Authors: Fan Yong
Published: December 2007

This paper introduces an interpretation model for fracture-calibration tests conducted in both low- and high-permeability reservoirs. The model is based on a detailed description of fluid flow into the porous medium with considerations of variable filtercake, non-Newtonian invasion effects, and superposition of fracture pressure. The leakoff rate is determined by the pressure profile instead of presumption of leakoff mode. This work, incorporating mass balance with principles of fluid and solid mechanics, provides a straight-line technique for determining formation permeability and fracture filtercake resistance. The determined pressure drops from the fracture face into the reservoir allow the separate computation of the compressibility-controlled component of leakoff and the combined filtercake and non-Newtonian invasion components. Leakoff is pressure-dependent.

Case studies of actual treatments are provided to demonstrate the new model and its interpretation. Comparisons are made to elucidate the similarities and differences between the traditional method and the new method. The new method accounts for fluid leakoff more accurately, allows for better fracturing design, and is particularly attractive for the tip screenout fracturing (frac-pack) treatments conducted in medium-to-high permeability formations.
HEC Precipitation at Elevated Temperature: An Unexpected Source of Formation Damage
Authors: Hodge R. M.
Published: December 2007

High-molecular-weight polymers are routinely used to viscosify brines for drilling, workover, and completion operations. Of the commercially available polymers, hydroxyethyl cellulose (HEC) is among the most versatile and widely used products. HEC has been used in NaCl, NaBr, KCl, NH4Cl, CaCl2, and CaBr2 brines over a wide range of brine density, pH environment, and temperature. Typically, the performance issues addressed in HEC studies focus on dispersibility, hydration rate and viscosity development, rheology at elevated temperature, and formation damage. Under typical oilfield conditions, the published data indicate that HEC produces minimum formation damage and provides predictable rheological behavior when properly prepared.
Pressure Drop in a Perforated Pipe With Radial Inflow: Single-Phase Flow
Authors: Schulkes Ruben M.S.M. , Utvik Ole Harald
Published: December 2007

In this paper we study the flow in a perforated pipe where fluid enters the pipe through the perforations. The focus of the paper is to describe and understand the evolution of the pressure field inside the pipe as a result of the radially inflowing fluid. Details of extensive single-phase experimental measurements are reported. A first-generation model which describes trends observed in the experiments is presented.
Transient Pressure Behavior of Dual-Lateral Wells
Authors: Ozkan Erdal , Yildiz Turhan , Kuchuk F. J.
Published: December 2007

The objective of this paper is to investigate the transient pressure behavior of dual-lateral wells. An analytical solution to compute the pressure responses of dual-lateral wells in the Laplace domain is presented, and the computational issues are addressed. The influences of the length, phase angle, and vertical and horizontal separations of the laterals are discussed. New flow regimes are identified and the conditions under which various flow regimes prevail are documented. Guidelines for the well test analysis of dual-lateral well responses are also presented.
The Group III Shaly Sand Data Set
Authors: Hofman J. P. , de Kuijper A. , Sandor R. K. J. , Hausenblas M. , Bonnie R. J. M. , Fens T. W.
Published: December 2007

In the development of shaly sand saturation models, core data are of exceptional value. These data are required to check the descriptive and predictive power of existing models and compare them with new concepts. This paper aims to add to the modest set of generally available core data on shaly sands by presenting a variety of special core-analysis measurements on a number of shaly sand core samples.

The experiments presented here include standard petrophysical measurements, continuous injection (CI) resistivity measurements (at ambient and elevated temperatures), nuclear magnetic resonance experiments (t1 and t2 acquisitions on fully brine-saturated samples; t2-diffusion measurements with an external magnetic gradient on partially brine-saturated samples), and scanning electron microscopy (SEM) images that have been subjected to image analysis.
Underbalance Perforation in Long Horizontal Wells in the Andrew Field
Authors: Kusaka Koji , Patel Dinesh , Gomersall Sam , Mason John , Doughty Phil
Published: December 2007

Andrew field in the U.K. Continental Shelf, which is operated by British Petroleum (BP) Exploration, is being developed using horizontal oil producers and completed with cemented liners. The main challenges of perforating these wells are maximizing well productivity by avoiding formation damage, minimizing the possibility of sanding, maximizing ultimate hydrocarbon recovery, perforating long horizontal sections safely and efficiently, optimizing the economic value of perforating, and minimizing perforating debris.

In general, to avoid impairing well productivity, it is best to perforate the underbalance. However, the advantage is compromised, because of the fluid invasion and loss-control material, if a well will be killed when the tubing-conveyed perforating (TCP) guns are removed. Existing deployment methods with coiled tubing (CT) enable perforation and subsequent gun removal in an underbalance condition. Unfortunately, various limitations would require multiple runs with CT for perforating each horizontal well in the Andrew field, which would result in significant time and unbalance perforation for each subsequent run.

The combination of the newly developed mechanical ball valve and the deployment of TCP guns with hydraulic workover units enables long horizontal wells to be perforated in one run in underbalance, and enables the guns to be removed without killing the well. Specially engineered guns and perforating charges are used to minimize sanding and gun debris.

This paper describes how these new technologies, used for perforating operations, meet many challenges. The same technologies can be used readily for perforating other long horizontal wells with similar problems.

To date, three horizontal wells in Andrew field were perforated successfully with the method described in this paper. The initial results indicate that the combination of the cemented liner completion, the engineered perforation systems, and the correct TCP gun deployment method using the mechanical deployment valve have contributed to improve well performance, to reduce cost, and to improve operability and safety in long horizontal wells.
The Benefits of Logging While Drilling (LWD) for Formation Evaluation in the Dulang West Field
Authors: Amar Zarool Hassan Bin Tajul
Published: December 2007

Ever since the first electric log was run in 1927, the oil industry relied on wireline-conveyed logging for the acquisition of formation data for petrophysical analysis. It was not until 1978 that the first measurement while drilling (MWD) tools were introduced in the field. The industry did not pay too much attention to them then because they did not offer sufficient information for petrophysical analysis. Furthermore, the reliability of such tools was not impressive and their cost was unattractive.

However, over the last 6 years, the drilling services industry has shifted its focus from just directional MWD to a complete directional and logging while drilling (LWD) package. The LWD tools that are built into special drill collars provide measurements of resistivity, neutron, density, and gamma ray. Significant improvements in the reliability of the tools and competitive pricing, as compared to conventional wireline logging, has offered advantages in running LWD in fields that have drilling and completion constraints (e.g., borehole stability) or difficult well trajectories.

This paper discusses the benefits to Petronas Carigali of using LWD for formation evaluation. In the development of the Dulang West field, LWD was used extensively to acquire formation log data. The quality of the data and cost savings are addressed. A comparison between the wireline-conveyed and LWD data acquired in this field is also presented.

The acquisition of formation data by use of LWD in Dulang West has made a significant contribution to the overall cost per barrel of oil produced, without compromising data quality.
Influence of Connate Water and Condensate Saturation on Inertial Effects in Gas/Condensate Reservoirs
Authors: Lombard J.-M. , Longeron D. G. , Kalaydjian F. J. M.
Published: December 2007

In the near-wellbore region of gas/condensate wells, high-pressure gradients induce both large condensate saturation and high gas velocities which may lead to significant deviations from Darcy's law for gas permeability. At the present time, no physically relevant model exists which takes into account these non-Darcian two-phase flow phenomena. Using a specific laboratory equipment, a laboratory study has been performed with the aim to estimate the influence of pore structure and connate water saturation Swi on the gas inertial coefficient βg, and to integrate the effect of the condensate dropout in the Forchheimer flow equation. Experiments were conducted on sandpacks and sandstone core samples. For dry gas floods, the measured βg values were found in good agreement with previous published data. For gas floods in presence of Swi, βg was found to increase with Swi and a new correlation between βg and a mean-pore radius r¯ is proposed. Gas/ condensate (C1–C3 mixtures) steady-state experiments showed that βg values increased with the total liquid saturation.
A Simplified Approach to Geochemical Modeling and Its Effect on Mineral Precipitation
Authors: Araque-Martinez A. , Lake Larry W.
Published: December 2007

Solids can easily cause flow restrictions by plugging flow channels. A source of these solids is the dissolution and subsequent precipitation of minerals caused by the transport of fluids not in chemical equilibrium with the host formation. The term transport describes fluid convection throughout this paper. To model these geochemical processes, allowing for the transport of fluids with kinetic reactions, it is necessary to solve the mass-balance equations for each component flowing in the medium. This work presents a new approach, based on the method of characteristics (MOC), to greatly simplify these solutions. Based on this solution technique, we build a model that includes kinetic (aqueous/solid) as well as equilibrium (aqueous/aqueous) reactions. We define new dimensionless groups to scale the solution. Unlike several previous geochemical models, we focus on flow that is substantially out of local thermodynamic equilibrium.

The MOC model has been tested against results from the more general geochemical KGEOFLOW simulator and against experimental literature data. Results match the KGEOFLOW solution closely, but with at least 50 times less computing time. The MOC model can run quite general geochemical problems on a desktop personal computer (PC).

We applied the MOC model to radial flow around a well to study the effect of dissolution, supersaturation, and precipitation on injection wells. We focused on cases in which there was substantial mineral precipitation in calculations based on local thermodynamic equilibrium. Results show that at nearly all rates, mineral precipitation can occur, though the amount will be less than when local thermodynamic equilibrium is assumed. However, injection rates must be unrealistically large to completely prevent precipitation.
Viscous-Elastic Polymer Fluids Rheology and Its Effect Upon Production Equipment
Authors: Demin Wang , Youlin Jiang , Yan Wang , Xiaohong Gong , Gang Wang
Published: December 2007

Overview

The rheology of polyacrylamide solutions and the effect of viscous-elastic fluids upon production equipment are described. Methods to solve the negative effects of viscous-elastic fluids on equipment are also introduced.

The results of the modification(s) on the system and equipment show that the service life of equipment more than doubled, mechanical degradation of polymer decreased more than 50%, and energy consumption decreased markedly.

Most flow systems and equipment for the injection, production, and gathering of large amounts of fluid are designed for Newtonian fluids. Now, an increasing number of oil fields are on viscous-elastic flooding. After flooding by polyacrylamide (PAM) fluids, it was seen that the flow of this type of fluid in production and surface systems and equipment has its special characteristics, which in turn require special designs for the equipment and flow process.

This paper introduces the actual performance of the production and surface flow systems and equipment, and points out the influence that the special rheologic characteristics, especially the viscous-elastic nature of the fluid, has on the system and the modification made. For example, there is a normal force acting on the beam pump sucker rods that causes pronounced eccentric mechanical wear on one side of the sucker rods and thereby very short service life for beam-pump wells. This normal force significantly lowers the efficiency of centrifugal pumps, increases the vibration and mechanical degradation in triplex pumps and the whole system, lowers the efficiency of maturing tanks and static mixers, etc.

The modifications on the system and equipment and their results are shown. For example, the service life of beam pumps more than doubled; mechanical degradation of polymer in the system and triplex pumps decreased more than 50 and 70%, respectively; and the energy consumption of mixing equipment decreased 80%, among other results.
Management of Typhoon: A Subsea, Deepwater Development
Authors: Ring Jasper N. , Bourgeois Christine S. , Howard James , Melillo Allan J. , Neal Scott L. , Smith Steve
Published: December 2007

Typhoon, located in the Green Canyon area of the Gulf of Mexico, is a joint deepwater development between ChevronTexaco (operator) and BHP Billiton. First oil was realized in July 2001, just 6 years after acquiring the leases. The Typhoon development consists of a mini-tension-leg platform (TLP) with four subsea wells in approximately 2,100 ft of water. Recently, Boris, a joint project between BHP Billiton (operator), ChevronTexaco, and Noble Energy Partners was discovered in an adjacent block, and two subsea wells were tied back to the TLP. The field consists of several hydrocarbon-bearing sands with 60% of the field's proven reserves located within a single reservoir.

Characteristics typical of many deepwater developments (such as high flow rates, compartmentalization, reservoir compaction, and asphaltene precipitation) are prevalent at Typhoon. As a result, asset management is complex and requires each well to be managed independently. The primary purpose of this paper is to describe how the asset and wells are managed and to heighten the awareness of associated complexities. This will be achieved by providing an overview that includes well and reservoir performances to date, reservoir management processes, and idiosyncrasies associated with operating a deepwater, subsea development in the Gulf of Mexico.
Increasing the Computational Speed of Flash Calculations With Applications for Compositional, Transient Simulations
Authors: Rasmussen Claus P. , Krejbjerg Kristian , Michelsen Michael L. , Bjurstrøm Kersti E.
Published: December 2007

Approaches are presented for reducing the computation time spent on flash calculations in compositional, transient simulations. In a conventional flash calculation, the majority of the simulation time is spent on stability analysis, even for systems far into the singlephase region. A criterion has been implemented for deciding when it is justified to bypass the stability analysis. With the implementation of the developed time-saving initiatives, it has been shown for a number of compositional, transient pipeline simulations that a reduction of the computation time spent on flash calculations by approximately 85 to 90% can be achieved.
A Design Approach for a "Self-Lifting" Method To Eliminate Severe Slugging in Offshore Production Systems
Authors: Tengesdal J. Ø. , Thompson Leslie , Sarica Cem
Published: December 2007

Recently, exploitation of offshore petroleum reservoirs has moved to ever-increasing water depths. Production from fields in water deeper than 1800 m is now a reality. The use of long deepwater risers that conduct production from multiple wellheads on the seafloor to the surface predisposes the system to severe slugging in the riser for a wide range of flow rates and seabed topography. Considering the length of the deepwater risers, the problem is expected to be more severe than in production systems installed in shallower waters. Severe slugging could occur at a high pressure, with the magnitude of the pressure fluctuations so large as to cause a shorter natural-flow period with subsequent consequences, such as premature field abandonment, loss of recoverable reserves, and earlier-than-planned deployment of boosting devices.

In this study, a novel idea to lessen or eliminate severe slugging in pipeline/riser systems has been investigated. The principle of the technique is to transfer the pipeline gas to the riser at a point above the riser base. The transfer process will reduce both the hydrostatic head in the riser and the pressure in the pipeline, consequently lessening or eliminating the severe slugging by maintaining the steady-state two-phase flow in the riser.

In this paper, a steady-state model is presented. It can be used as a design tool for the self-lifting concept by determining the operation envelope for a successful self-lift operation; given the location of the gas takeoff or injection points, it can predict the acceptable range of pressure losses in the gas bypass for continuous steady-state operation of the self-gas-lift system. The model was found to perform very well when compared to the acquired experimental data.
Effect of Scaleup and Aggregation on the Analysis of Interference Tests
Authors: Raghavan Rajagopal , Roesler Ralph R. , Tureyen O. Inanc
Published: December 2007

The objective of this paper is to demonstrate the influence of detailed, small-scale heterogeneities on interference tests. Specific issues encountered when interference tests are analyzed in reservoirs with complex geological properties are discussed. These issues relate to questions concerning the use of low-resolution models, the degree of aggregation, the methodology of scaleup, and the reliability of conventional methods of analysis.

This paper demonstrates the importance of capturing fine-scale heterogeneities to replicate the true transient behavior of interference tests at both active and observation wells. The paper shows the effects of aggregation and scaleup as used routinely in the industry on evaluating transient responses. The consequences of using low-resolution models in systems with complex geology is also demonstrated. If low-resolution models are used, reservoir properties may be adjusted unrealistically to match the transient behavior observed in high-resolution models. Though scaleup preserves pore volume, estimates of storativity predicted by low-resolution models will have a significant effect on reservoir behavior and resource management. If porosity values are not regressed, significant changes in vertical permeability values are observed. This is an important observation with potentially dramatic effects on reservoir performance, especially in processes involving mobility differences. Regression on a single-layer model (homogeneous, or based on aggregation) was also shown to yield totally different geological outcomes. This also shows the need to use geological constraints during inversion, aggregation, and scaleup.
Improvements in Single-Phase Paraffin Deposition Modeling
Authors: Hernandez O. C. , Hensley H. , Sarica C. , Brill J. P. , Volk M. , Delle-Case E.
Published: December 2007

Paraffin deposition under single-phase flow conditions was investigated to determine its dependence on shear stripping, deposit aging, flow regime, temperature gradient, and fluid properties.

In this study, a new model for the prediction of single-phase wax deposition has been developed. Most of the models previously used assume that equilibrium exists at the deposit-fluid interface. A kinetic resistance of the fluid is considered in the new model. Therefore, the interfacial-wax concentration might be different from the equilibrium-wax concentration. The model also includes continuous diffusion of wax into the deposit. We believe that this enrichment of the deposit is responsible for the increasing hardness of the deposit with time - a process known as "aging." The effect of shear stripping may also be incorporated in the prediction.

The model predictions are compared with predictions from previous models, as well as with experimental data gathered at the Tulsa U. Paraffin Deposition Projects, with two different oils: a black oil and a condensate. Even though some tuning is required for each type of oil, the new model is based on physical phenomena, reducing the empiricism of previous models.
Evaluation of the Salinity Gradient Concept in Surfactant Flooding
Authors: Hirasaki G. J. , van Domselaar H. R. , Nelson R. C.
Published: December 2007

Salinity design goals are to keep as much surfactant as possible in the active region and to minimize surfactant retention. Achieving these is complicated because (1) compositions change as a result of dispersion, chromatographic separation of components distributed among two or more phases, and retention by adsorption onto rock and/or absorption in a trapped phase; (2) in the presence of divalent ions, optimal salinity is not constant but a function of surfactant concentration and calcium/sodium ratio; and (3) the changing composition of a system strongly influences transport of the components.

A one-dimensional (1D) six-component finite-difference simulator was used to compare a salinity gradient design with a constant salinity design. Numerical dispersion was used to evaluate the effects of dispersive mixing. These simulations show that, with a salinity gradient, change of phase behavior with salinity can be used to advantage both to keep surfactant in the active region and to minimize retention. By contrast, under some conditions with a constant salinity design, it is possible to have early surfactant breakthrough and/or large surfactant retention.

Other experiments conducted showed that high salinity does retard surfactant, and, if the drive has high salinity, a great amount of surfactant retention can result. The design that produced the best recovery had the waterflood brine overoptimum and the drive underoptimum; the peak surfactant concentration occurred in the active region and oil production ceased at the same point.
Cruse Steamflood Expansion Case History
Authors: Ramlal V.
Published: December 2007

The Cruse ‘E’ steamflood was designed and developed by Petrotrin from 1994 to 1996. This paper discusses the performance of the steamflood during steam injection and during a 4-year period of noninjection. It also covers the operational and economic aspects of the project and discusses the production response since restart, the amended forecast from history-matched reservoir simulation, and future operating strategies.
Optimization of Riser Design and Drill Centers With a Coupled Reservoir and Facility-Network Model for Deepwater Agbami
Authors: Narahara G. M. , Holbrook J. A. , Shippen M. , Erkal A.
Published: December 2007

The use of multiple wells connected at a subsea manifold provides the opportunity to reduce the number of risers and capital expense. The problem is the proper modeling of the reservoir well flow coupled with the combined flow into the facility network (i.e., manifolds, flowlines, and risers), which is necessary to prevent underdesign, resulting in flow-rate bottlenecks, or overdesign, resulting in extra expenditures. This paper presents a tool and methodology for better modeling of the well-to-riser flow and the optimization of riser count and configuration.

Although reservoir models coupled with facility networks is not new, software enhancements provided the capability of including operation logic that could duplicate operations in the field. The reservoir model coupled with the facility network provided more reasonable and accurate modeling of multiphase rates and pressures as wells were combined into a single riser.

To optimize the riser count, operation logic was applied to maximize rate in the riser at all times against the erosional-velocity limit. This in turn prevented overdesigning by placing more risers than needed to obtain the field-facility capacities.

The use of the coupled model and operation logic allowed the optimization of the riser count for any particular reservoir model. The optimum riser count was then determined for 3 earth (geologic) models.
Heavy Oil and Bitumen Dehydration—A Comparison Between Disc-Stack Centrifuges and Conventional Separation Technology
Authors: Agrell J. , Faucher M.
Published: December 2007

Recent technological advances are making the exploitation of heavy crude oil reserves increasingly profitable. This paper compares nozzle-type disc-stack centrifuges to conventional separation technology for dehydration of heavy oil and bitumen.

The nature and composition of heavy oil leads to a number of undesirable properties, such as its tendency to form stable emulsions in the presence of asphaltenes, particles, and other emulsifiers occurring naturally in the oil. This, combined with a high viscosity and a relatively high solids content, makes dehydration a challenging task that introduces new concerns when compared to dehydrating light crude oil.

As the density of the heavy oil increases and approaches that of water, conventional static and gravity-based separation systems become unacceptably large and require excessive heating and chemical addition to produce pipeline-specification oil. Hence, the disc-stack centrifuge is proposed as a compact and efficient solution, enabling breakdown of stable emulsions and removal of dispersed water droplets and solid contaminants from heavy and viscous crudes in both onshore and offshore installations.
Restoration of a constructed stormwater wetland to improve its ecological and hydrological performance
Authors: Jenkins Graham A. , Greenway Margaret
Published: December 2007

Although the vegetation within constructed stormwater wetlands plays an important role in the treatment processes taking place, its density and distribution depends on the wetland bathymetry and the imposed hydrologic regime. This paper describes an ecological and hydrological assessment of a constructed stormwater treatment wetland over a 5 year period. This assessment included the use of a continuous simulation hydrologic model combined with a Digital Elevation Model of the wetland bathymetry, plus a time series of vegetation maps. The combined spatial and temporal analysis indicates that both the frequency and duration of inundation has affected the fate of vegetation throughout the wetland. Restoration strategies have also been investigated to improve the survival of vegetation within the wetland.
Particle behaviour consideration to maximize the settling capacity of rainwater storage tanks
Authors: Han M.Y. , Mun J.S.
Published: December 2007

Design of a rainwater storage tank is mostly based on the mass balance of rainwater with respect to the tank, considering aspects such as rainfall runoff, water usage and overflow. So far, however, little information is available on the quality aspects of the stored rainwater, such as the behavior of particles, the effect of retention time of the water in the tank and possible influences of system configuration on water quality in the storage tank. In this study, we showed that the performance of rainwater storage tanks could be maximized by recognizing the importance of water quality improvement by sedimentation and the importance of the system configuration within the tank, as well as the efficient collection of runoff. The efficiency of removal of the particles was increased by there being a considerable distance between the inlet and the outlet in the rainwater storage tank. Furthermore, it is recommended that the effective water depth in a rainwater tank be designed to be more than 3 m and that the rainwater be drawn from as close to the water surface as possible by using a floating suction device. An operation method that increases the retention time by stopping rainwater supply when the turbidity of rainwater runoff is high will ensure low turbidity in the rainwater collected from the tank.
A Central Role for Neuronal AMP-Activated Protein Kinase (AMPK) and Mammalian Target of Rapamycin (mTOR) in High-Protein Diet–Induced Weight Loss
Authors: Ropelle Eduardo R. , Pauli José R. , Fernandes Maria Fernanda A. , Rocco Silvana A. , Marin Rodrigo M. , Morari Joseane , Souza Kellen K. , Dias Marília M. , Gomes-Marcondes Maria C. , Gontijo José A.R. , Franchini Kleber G. , Velloso Lício A. , Saad Mario J.A. , Carvalheira José B.C.
Published: December 2007

OBJECTIVE—A high-protein diet (HPD) is known to promote the reduction of body fat, but the mechanisms underlying this change are unclear. AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) function as majors regulators of cellular metabolism that respond to changes in energy status, and recent data demonstrated that they also play a critical role in systemic energy balance. Here, we sought to determine whether the response of the AMPK and mTOR pathways could contribute to the molecular effects of an HPD.

RESEARCH DESIGN AND METHODS—Western blotting, confocal microscopy, chromatography, light microscopy, and RT-PCR assays were combined to explore the anorexigenic effects of an HPD.

RESULTS—An HPD reduced food intake and induced weight loss in both normal rats and ob/ob mice. The intracerebroventricular administration of leucine reduced food intake, and the magnitude of weight loss and reduction of food intake in a leucine-supplemented diet are similar to that achieved by HPD in normal rats and in ob/ob mice, suggesting that leucine is a major component of the effects of an HPD. Leucine and HPD decrease AMPK and increase mTOR activity in the hypothalamus, leading to inhibition of neuropeptide Y and stimulation of pro-opiomelanocortin expression. Consistent with a cross-regulation between AMPK and mTOR to control food intake, our data show that the activation of these enzymes occurs in the same specific neuronal subtypes.

CONCLUSIONS—These findings provide support for the hypothesis that AMPK and mTOR interact in the hypothalamus to regulate feeding during HPD in a leucine-dependent manner.
Insulin Internalizes GLUT2 in the Enterocytes of Healthy but Not Insulin-Resistant Mice
Authors: Tobin Vanessa , Le Gall Maude , Fioramonti Xavier , Stolarczyk Emilie , Blazquez Alba G. , Klein Christophe , Prigent Magali , Serradas Patricia , Cuif Marie-Hélène , Magnan Christophe , Leturque Armelle , Brot-Laroche Edith
Published: December 2007

OBJECTIVES—A physiological adaptation to a sugar-rich meal is achieved by increased sugar uptake to match dietary load, resulting from a rapid transient translocation of the fructose/glucose GLUT2 transporter to the brush border membrane (BBM) of enterocytes. The aim of this study was to define the contributors and physiological mechanisms controlling intestinal sugar absorption, focusing on the action of insulin and the contribution of GLUT2-mediated transport.

RESEARCH DESIGN AND METHODS—The studies were performed in the human enterocytic colon carcinoma TC7 subclone (Caco-2/TC7) cells and in vivo during hyperinsulinemic-euglycemic clamp experiments in conscious mice. Chronic high-fructose or high-fat diets were used to induce glucose intolerance and insulin resistance in mice.

RESULTS AND CONCLUSIONS—In Caco-2/TC7 cells, insulin action diminished the transepithelial transfer of sugar and reduced BBM and basolateral membrane (BLM) GLUT2 levels, demonstrating that insulin can target sugar absorption by controlling the membrane localization of GLUT2 in enterocytes. Similarly, in hyperinsulinemic-euglycemic clamp experiments in sensitive mice, insulin abolished GLUT2 (i.e., the cytochalasin B-sensitive component of fructose absorption), decreased BBM GLUT2, and concomitantly increased intracellular GLUT2. Acute insulin treatment before sugar intake prevented the insertion of GLUT2 into the BBM. Insulin resistance in mice provoked a loss of GLUT2 trafficking, and GLUT2 levels remained permanently high in the BBM and low in the BLM. We propose that, in addition to its peripheral effects, insulin inhibits intestinal sugar absorption to prevent excessive blood glucose excursion after a sugar meal. This protective mechanism is lost in the insulin-resistant state induced by high-fat or high-fructose feeding.
Extended Cartographic Interfaces for Open Distributed Processing
Authors: Sykora Peter , Schnabel Olaf , Enescu Ionut Iosifescu , Hurni Lorenz
Published: December 2007

In recent years, cartographic Web applications have evolved from closed monolithic applications to open distributed systems in which real-time map rendering components and services play an important role. This progress has required new and flexible ways of defining map symbolization. The development of cartographic interfaces needed to describe the desired map output offers the means to extend current symbolization approaches and adapt the portrayal of data to the most demanding requirements in the area of distributed thematic mapping.

This article analyses, in the context of open distributed processing, some of the existing cartographic interfaces that can be used for various cartographic applications and services. At the same time, the article offers a look at the most recent research efforts in this area.
Role of Viscosity in Dynamic Creep Tests in Conventional, Oxidized, and Polymer-Modified Asphalts
Authors: Wasage Thamindra Lakshan Jayanthi , Cantu Matteo , Stastna Jiri , Polacco Giovani , Zanzotto Ludo
Published: December 2007

A dynamic creep test was proposed as a new method for evaluating the ability of modified asphalt binders to maintain their elastic response. The test was readily proposed to evaluate the resistance to rutting of asphalt pavements. The authors are reporting the analysis of results of the dynamic creep test on several conventional and oxidized asphalts and blends of conventional asphalts with two polymers. The used polymers were styrene-butadiene-styrene and styrene-(ethylene-co-butylene)-styrene. The effects of temperature, material (base asphalt and polymer modifier), applied stress level, and oxidation were investigated. The possibility of using linear viscoelastic models for the description of the dynamic creep test was also studied.