bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Finite-Element-Calculated Magnetic-Flux-Leakage Signals To Study the Characterization of Defects in Steel Coiled Tubing
Authors: Breidenthal Chase , Larín Gabriel E. , Tipton Steven M. , Stanley Roderic K. 
Published: March 2009

Summary
A primary consideration with coiled tubing (CT) is that it is consumed by fatigue loading during routine operations. Also, rugged oilfield conditions routinely lead to corrosion and other mechanical surface damage. Since fatigue is a surface phenomenon, the presence of a surface imperfection has a significant influence on fatigue-damage mechanisms. This paper describes the study of magnetic-flux-leakage (MFL) inspection signals caused by surface defects in the form of milled circumferential grooves in steel CT. The focus of the investigation is to identify and estimate the size of surface defects on the basis of characteristic MFL signal features. It is demonstrated that this effort is greatly enhanced by finite-element analysis (FEA). The ultimate objective is to extract surface-flaw dimensions accurately from conventional MFL signals. These dimensions are used in computer CT life-prediction models.
An axisymmetric FEA model is developed and used to calculate leakage flux density solutions for milled circular and rectangular shaped grooves in 1.75-in.-outside-diameter (OD), 0.156-in.-wall-thickness (WT), 90-ksi CT samples. FEA results are compared to axial and radial MFL signals measured with an experimental inspection unit. Favorable agreement is observed between experimental and FEA data. Furthermore, signal features are correlated with the known slot geometries to identify basic geometry-recognition patterns for different circumferential grooves. Signal features reveal qualitative and quantitative trends relative to surface-flaw dimensional characteristics.
The need persists to make the operator's string-management decision-making process more reliable and automatic with respect to determining fatigue life expectancy. The obstacle here is that because of the inherent inaccuracies in commonly used MFL inspection techniques, reliable real-time flaw-evaluation and -characterization capability is limited.
Flow Reversal and Mixing
Authors: Jha Raman K. , John Abraham K. , Bryant Steven L. , Lake Larry W. 
Published: March 2009

Summary
Flow-reversal studies provide insights into mixing mechanisms in flow through porous media. In these studies, the direction of flow is reversed after the solute slug has penetrated into the medium (but not exited) to a predetermined distance. We simulated the effect of flow reversal on mixing in 2D porous media using two different approaches. In the first approach, we perform direct numerical simulation of a solute-slug transport (by solving Navier-Stokes and convection/diffusion equations) in a surrogate pore space. This approach allows a direct visualization of mixing in simple flow geometries. The effect of flow reversal on mixing is investigated for several diffusion coefficients, penetration depths, and flow geometries. The second approach uses particle tracking to simulate the effect of flow reversal at larger length scales. This approach is free of numerical dispersion, can be used in the absence of diffusion, and has no limits on the size of the simulation. It is, however, limited to layered-media flow.
The simulation studies presented in this paper explain the mechanism of mixing and the origin of the irreversibility of dispersion in flow through porous media. We also explain several experimental observations on flow-reversal tests found in the literature.
Mixing in porous media takes place because of interaction between convective spreading and molecular diffusion. The con-verging/diverging paths and flow around impervious sand grains cause the solute front to stretch and split. In this process, the area of contact between the solute slug and the resident fluid increases by an order of magnitude and diffusion becomes an effective mixing mechanism. This local mixing, caused by diffusion, is irreversible.
For purely convective transport, solute particles retrace their path back to the inlet upon flow reversal. Convective spreading gets canceled, and echo dispersion is 0. Diffusion, even though small in magnitude, is responsible for local mixing and making dispersion in porous media irreversible. Thus, it is important to include the effect of diffusion when analyzing miscible displacements in porous media.
Numerical Method of Evaluating Elemental Content of Oil-/Water-Saturated Formations Based on Pulsed-Neutron Gamma Inelastic Log Data
Authors: Khisamutdinov A. I. , Phedorin M. A. 
Published: March 2009

Summary
A numerical method is proposed for solving an inverse problem for a pulsed-neutron gamma inelastic log. The objective is to determine a composition of the in-pore fluid and of the rock skeleton by gamma ray measurement data in spectral windows of four elements: C, O, Ca, and Si. Inversion of the data is based on an iteration procedure, on each step of which the corresponding direct problem is solved for transport equations of neutrons and gamma quanta. Results of numerical experiments are presented that confirm a convergence to exact solution for most of the unknowns. The proposed numerical method is the development of an approach for solving inverse problems in nuclear geophysics (Khisamutdinov and Blankov 1989; Khisamutdinov and Minbaev 1995; Khisamutdinov 1999; Khisamutdinov and Phedorin 2003; Khisamutdinov 2005).
Multiscale Mixed-Finite-Element Modeling of Coupled Wellbore/Near-Well Flow
Authors: Krogstad S. , Durlofsky L. J. 
Published: March 2009

Summary
An accurate well-modeling capability is important for both production- and reservoir-engineering calculations. Ideally, the models used for these two applications should be related in a logical manner. Multiscale methods allow varying degrees of resolution and can, therefore, provide a natural link between production and reservoir models. In this paper, we present a coupled wellbore-/reservoir-flow model that is based on a multi-scale mixed-finite-element formulation for reservoir flow linked to a drift/flux wellbore-flow representation. The model is able to capture efficiently the effects of near-well heterogeneity in the reservoir and phase holdup and pressure variation in the well-bore. The formulation presented here is for oil/water systems. The basic reservoir/wellbore linkage is described and validated through comparison to results from an existing simulator. The multiscale method is then applied to a heterogeneous-reservoir model. Both vertical and deviated wells are considered. Comparisons of the multiscale solution to the fully resolved (fine-scale) solution demonstrate the efficiency and high degree of accuracy of the method for both reservoir and wellbore quantities.
A Rigorous Pore-to-Field-Scale Simulation Method for Single-Phase Flow Based on Continuous-Time Random Walks
Authors: Rhodes Matthew E. , Bijeljic Branko , Blunt Martin J. 
Published: March 2009

Summary
We propose a pore-to-reservoir simulation approach for single-phase flow. Transport is modeled as a continuous-time random walk (CTRW). Particles make a series of transitions between nodes with a probability ψ(t)dt that a particle will first arrive at a node from a nearest neighbor in a time t to t+dt. A top-down multi-scale approach is used to find the flow field. At the micron scale, ψ(t) for particle transitions from pore to pore are found from modeling advection and molecular diffusion in a geologically representative network model. This ψ(t) is used to compute transport on the millimeter-to-centimeter scale. At larger scales, we represent the reservoir as a network of nodes connected by links. For each node-to-node transition, we compute an upscaled ψ(t) from a simulation of transport at the smaller scale. We account for small-scale uncertainty by interpreting ψ(t) probabilistically and running simulations for different possible realizations of the reservoir model. To make the number of computations manageable, ψ(t)is parameterized in terms of subscale heterogeneity and Péclet number, meaning that only a few representative simulations are required.
We apply this method by finding ψ(t) for pore-scale flow and using it in a million-cell reservoir model. We show that the macroscopic behavior can be very different from that predicted by assuming that the advection/dispersion equation (ADE) operates at the small scale. Small-scale structure does affect macroscopic transport; increasing the pore-level heterogeneity delays breakthrough and leads to longer late-time tails of the production because the solute spends more time in slow-flowing regions of the domain. We discuss extensions to multiphase flow and the development of a novel network-based probabilistic reservoir-simulation approach.
Numerical Analysis of Condensate-Flow Impairment in Retrograde-Gas Naturally Fractured Reservoirs and Its Interplay With the Estimation of Diffusion Coefficients
Authors: Ayala Luis F. , Radespiel Eduardo , Ertekin Turgay 
Published: March 2009

Summary
Previous studies dedicated to the analysis of retrograde condensation in naturally fractured gas/condensate reservoirs have concluded that the presence of a multimechanistic-flow environment in tight naturally fractured reservoirs hosting retrograde gases can have a great effect on the depletion behavior of the reservoirs (Ayala et al. 2004; Ayala et al. 2006; Ayala et al. 2007). In these systems, condensate dropout below dewpoint conditions is typically immobile and greatly impairs the flow of the other phases, adversely affecting reservoir productivity and ultimate recovery. Whenever this flow impairment becomes severe, diffusion can take over as the main recovery mechanism. In such cases, fluid recovery is driven by both molecular-concentration fields (i.e., diffusive transport governed by Fick's law of diffusion) and the pressure field (i.e., bulk transport governed by Darcy's law). Previous multimechanistic studies relied upon the assumption that the diffusive flow component could be represented as a constant value throughout the reservoir's productive life. However, diffusion coefficients in hydrocarbon systems can be shown to vary significantly during the reservoir's producing life as a function of prevailing pressure, temperature, and composition conditions. The present study captures the influence that varying composition and fluid properties, such as density and viscosity, have on the value of the diffusion coefficient at different stages of reservoir depletion. It is concluded that the assumption of constant diffusive coefficients can yield good predictions for cases where fracture-depletion rates are small in particular. Diffusion coefficients and diffusive effects are also shown to exhibit a strong dependency on fracture-depletion rates. The present work reassesses the effect of multimechanistic flow on the isothermal depletion of tight, naturally fractured retrograde-gas reservoirs while capturing the full dependencies of the diffusion coefficient on reservoir fluid properties and their interplay with the formation of the condensate bank around matrix edges.
Imaging Fractures Using Temperature Transients From Perturbation Analysis—A Novel Surveillance Technique Applied to the Belridge Diatomite
Authors: Shahin G. T. , Johnston R. M. 
Published: March 2009

Summary
Results of a temperature transient analysis of data from Shell's diatomite steamdrive pilots are used to image hydraulic injection fracture lengths, angles, and heat injectivities into the low-permeability formation. The Phase I pilot is a limited-interval injection test. In Phase Π, steam is injected into two 350-ft upper and lower zones through separate hydraulic fractures. Temperature response of both pilots is monitored with 16 logging-observation wells.
A perturbation analysis of the nonlinear pressure diffusion and heat-transport equations indicates that at a permeability of approximately 0.1 md or less, heat transport in the diatomite tends to be dominated by thermal diffusivity, and pressure diffusion is dominated by the ratio of thermal expansion to fluid compressibility. Under these conditions, the temperature observed at a logging-observation well is governed by a dimensionless quantity that depends on the perpendicular distance between the observation well and the hydraulic fracture divided by the square root of time. Using this dependence, a novel method is developed for imaging hydraulic-fracture geometry and relative heat injectivity from the temperature history of the pilot.
The azimuth of the Phase I hydraulic fracture is determined to be 14° ± 2 N-NE. The azimuth of the Phase II upper hydraulic fracture is determined to be 16° ± 2 N-NE in the northern half of the pilot, and estimated to increase to 21° ± 2 in the southern half of the pilot. The azimuth of the lower hydraulic fracture averages 19° ± 4. The hydraulic fractures are found to be symmetric around both injectors, with an estimated length of 200 ft.
Increased steam injection after the first year of pilot operations caused what is interpreted to be horizontal fractures toward the west in the G cycle and the east in the M cycle. These features are imaged to be at least 100 and 160 ft, respectively, along the hydraulic fracture azimuth.
These conclusions are compared to tiltmeter data, microseismic data, and a simulation history match of pilot performance. Microseismic events recorded in the pilot are apparently not diagnostic of heat delivery to the formation.
Solubility Enhancement of Cox-II Inhibitors by Cosolvency Approach
Authors: Babu PR Sathesh , Subrahmanyam CVS , Thimmasetty J , Manavalan R , Valliappan K , Kedarnath SA 
Published: March 2009

Solubility enhancement of meloxicam and rofecoxib, which are poorly soluble in water, was attempted. These are available in the form of solid dosage forms but not in solution dosage forms due to their low aqueous solubility. In this work, aqueous solubility of meloxicam and rofecoxib was improved using the biocompatible solvents such as ethanol, propylene glycol, glycerin, and PEG 400. Physico-chemical properties of the solvents such as intermolecular interactions and the ability of the solvent to form a hydrogen bond with the drug molecules were found to be the major factors involved in the dissolution of drugs. It was found that less polar solvents were found to increase solubility by greater extent, thus accentuating hydrophobic interaction mechanism. Among the solvent blends studied, water-PEG 400 had highest solubilization potential. Thus, the study generated an important dataset so as to compare effect of various cosolvents on the solubility of the drugs. Key words: Aqueous solubility, Meloxicam, Rofecoxib, Cosolvency. doi: 10.3329/dujps.v7i2.2166 Â Â Â Dhaka Univ. J. Pharm. Sci. 7(2): 119-126, 2008 (December)
Impact of Urinary Arsenic Level on Simple Diffuse Goiter
Authors: Hossain Md Sharif , Begum Fatema 
Published: March 2009

The impacts of urinary arsenic level on simple diffuse goiter was studied in Bangladeshi population. A correlation of urinary iodine, radioiodine uptake, thyroid stimulating hormone (THS) and free thyroxin (FT4) levels was made on urinary arsenic level using a case-control analytical study. Out of 85 subjects 45 were considered for experimental group with simple diffuse goiter and rest 40 were considered for healthy control group without any thyroid disease. From the experimental results it has been found that iodine deficiency is not only the factor of causing simple diffuse goiter, but arsenic level is also one of the most important factors of causing simple diffuse goiter. It has also been found that the radioiodine uptake levels at 2 hours and 24 hours and the serum FT4 have negative impacts on arsenic levels for both the experimental and control group. Their impacts are not statistically significant except the variable radioiodine uptake levels at 24 hours. The serum TSH has positive impact on arsenic level for both experimental and control groups but not statistically significant. The estimated results revealed that the variable radioiodine uptake level at 24 hours play the significant role for reducing arsenic level. Key words: Urinary Arsenic, Iodine Deficiency, Simple Diffuse Goiter, Urinary iodine, Thyroid Stimulating Hormone, Free Thyroxin and Radioiodine Uptake Level doi: 10.3329/dujps.v7i2.2173 Â Â Â Dhaka Univ. J. Pharm. Sci. 7(2): 161-168, 2008 (December)
Two Views of History and Human Future: Qur'anic and Biblical Renderings of Divine Promises
Authors: Neuwirth Angelika 
Published: March 2009

Though the Qur'an refers to the Psalms as a scriptural corpus, al-zabūr, the Qur'anic relationship with the Psalms is – unlike that with the Torah or the Gospel – not explicitly described in terms of an affirming re-collection of that scripture. In the Qur'an ‘the Psalms’ as a scriptural authority play a rather marginal role. Yet individual psalm texts are strikingly present in the Qur'an. Not only are they reflected in numerous Qur'anic metaphors, but more generally, their particular vision of human-divine relations is closely related to that mirrored in the early suras. The paper attempts to trace the Qur'anic references to Psalm 136 which, it is argued, is theologically radically re-modelled in Sūrat al-Raḥmān (Q. 55), comparing the texts in order to explore the Qur'anic rejection of the Biblical notion of ‘history as a promise for the future’. It will posit that the new Qur'anic vision of the human future that eventually comes to replace the Biblical is not only a rejection of a previous option, it is at the same time a response to a major question raised in Pre-Islamic Arabic poetry. The Qur'an thus is in conversation with two cultural traditions; the options put forward in both being debated and finally replaced.
Deepwater Flowline Tie-Ins and Jumpers: What Works Best?
Authors: McKeehan D.S. , Freet T.G. 
Published: March 2009

Abstract
The diverless tie-in of pipelines has evolved into three techniques whichare being standardized for first or second end connections in depths of 1,000feet and deeper: lateral deflections, spool pieces, and vertical stab andhingeover. This paper discusses the trade-offs made when determining the mostcost-effective solution for deepwater flowline tie-ins and jumpers forwell-to-manifold tie-ins. Since deepwater tie-ins have a significant impact onpipeline economics, the selection process depends on many factors which areordinarily not considered in shallower depths.

Introduction
The DeepStar project selected the cluster satellite well and manifoldconcept for further development. A critical aspect of this modular equipmentarrangement is the numerous piping interconnections that must be made betweenthe satellite wells and the manifold; and, between the manifold andflowlines/riser bases.
Diverless tie-in of the satellite wells connects the small diameter pipesused for production (4"), well test (4"), hydraulic fluids (1") andchemical service (1") lines to the manifold. These "jumper" pipesrange from 60 ft to about 150 ft in length, depending upon the location of thewell relative to the manifold connection point. The connectors may be hydraulicor mechanical and operated by an ROV. With planning, it may be possible tomeasure, fabricate and install these jumpers from the field Mobile OffshoreDrilling Unit (MODU) while not interrupting the drilling operation.
Diverless tie-ins for "flowlines" of 8 to 20 inch diameter in awater depth range of 1,000 ft to 6,000 ft are being considered and implementedby operators as the technology advances. The increasing water depths and keeninterest by the engineering community have resulted in a variety of tools andtechniques being proposed for these tasks. The options available andlimitations of each frequently necessitate trade-off comparisons andengineering studies to establish the most practical arrangement for a specificfield development. This paper presents the applications and requirements ofconnection systems both for the flowline tie-ins and for the connection of thesatellite wells to the manifold. To focus discussion, the term "tie-in"represents the initial placement of the flowline and subsequent activitiesnecessary to align and position mating connector halves within theirself-engagement envelope. Similar to the jumper, the flowline connections areoptimized for ROV operation.
Deepwater Technology Limits and Development Barriers
Authors: Chitwood J.E. , Rothberg R.H. , Miller H.W. 
Published: March 2009

Abstract
A phased deepwater subsea cluster manifold producing over an extendeddistance to a shallow water host production platform has been evaluated forGulf of Mexico economic viability in the DeepStar program. This paper examinesexisting subsea production technology to identify upgrades and improvementsnecessary before a junctional and cost effective deepwater system can bedeployed. Beyond the basic technology upgrades, several cost reductiontechnologies are also identified.

Introduction
Subsea production system technology is presently suited for applications inwater as deep as 3000 - 3500 ft. The DeepStar program evaluated developmentalternatives in water as deep as 6000 ft in the Gulf of Mexico, and found thatexisting subsea technology can be extended to this depth with substantialfunctional similarity. Some basic differences exist as a result of location, reservoir conditions and the recommended seafloor facility arrangement. Thesedifferences are briefly identified to highlight technologies requiring furtherdevelopment. With technology upgrades, a working system could be assembled forthe deepwater Gulf, however, it may not be economically viable. Furthertechnology work, therefore, needs to focus upon cost reduction strategies toimprove deepwater field development economics.
The DeepStar project developed a phased modular production system. Thesubsea facilities feature clustered satellite wells around one or moremanifolds, linked by flowline jumpers. If required, subsea processing orpumping is placed in series between the manifold and the pipelines. Thesepipelines extend to an existing platform in shallow water on the continentalshelf. During the early project drilling phase, the subsea wells are producedto gain both information and confidence in the reservoir, and to improve theproject's economics. Each well is placed into production as it is completed. These subsea facilities are controlled from the Mobile Offshore Drilling Unit(MODU) until the drilling program is complete. The control umbilical to theshallow water host is then installed and tied-in to operate the field duringits production decline phase.