bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hierarchical Long-Term and Short-Term Production Optimization
Authors: van Essen G.M.. M. , Van den Hof P.M.J.. M.J. , Jansen J.D.. D. 
Published: October 2010

Summary
Model-based dynamic optimization of oil production has a significant potential to improve economic life-cycle performance, as has been shown in various studies. However, within these studies, short-term operational objectives are generally neglected. As a result, the optimized injection and production rates often result in a considerable decrease in short-term production performance. In reality, however, it is often these short-term objectives that dictate the course of the operational strategy. Incorporating short-term goals into the life-cycle optimization problem, therefore, is an essential step in model-based life-cycle optimization. We propose a hierarchical optimization structure with multiple objectives. Within this framework, the life-cycle performance in terms of net present value (NPV) serves as the primary objective and shortterm operational performance is the secondary objective, such that optimality of the primary objective constrains the secondary optimization problem. This requires that optimality of the primary objective does not fix all degrees of freedom (DOF) of the decision variable space. Fortunately, the life-cycle optimization problem is generally ill-posed and contains many more decision variables than necessary. We present a method that identifies the redundant DOF in the life-cycle optimization problem, which can subsequently be used in the secondary optimization problem. In our study, we used a 3D reservoir in a fluvial depositional environment with a production life of 7 years. The primary objective is undiscounted NPV, while the secondary objective is aimed at maximizing shortterm production. The optimal life-cycle waterflooding strategy that includes short-term performance is compared to the optimal strategy that disregards short-term performance. The experiment shows a very large increase in short-term production, boosting first-year production by a factor of 2, without significantly compromising optimality of the primary objective, showing a slight drop in NPV of only -0.3%. Our method to determine the redundant DOF in the primary objective function relies on the computation of the Hessian matrix of the objective function with respect to the control variables. Although theoretically rigorous, this method is computationally infeasible for realistically sized problems. Therefore, we also developed a second, more pragmatic, method relying on an alternating sequence of optimizing the primary-and secondary-objective functions. Subsequently, we demonstrated that both methods lead to nearly identical results, which offers scope for application of hierarchical long-term and short-term production optimization to realistically sized flooding-optimization problems.
Oil, Natural-Gas, and NGL Endowment in North, Central, and South America
Authors: Aguilera Roberto F. , Aguilera Roberto 
Published: October 2010

Summary
This study uses the United States Geological Survey (USGS) World Petroleum Assessment (USGS World Energy Assessment Team 2000) as a starting point. Then, it uses a previously defined variable-shape-distribution (VSD) model for estimating the endowment of oil, natural gas, and natural-gas liquids (NGL) throughout North, Central, and South America.
Use of the VSD model is validated by an excellent fit with actual data, supported by coefficients of determination (R2) equal to 0.98 or greater. The study includes endowments in petroleum provinces not assessed previously by other organizations. Endowment, as defined by the USGS, refers to the sum of known volumes of hydrocarbons (cumulative production plus remaining reserves) and undiscovered volumes. Petroleum is the sum of oil, natural gas, and NGL.
The importance of North, Central, and South America is highlighted by a hydrocarbon output during 2007 that accounted for 25% of the world oil production and more than 31% of the natural-gas production.
It is concluded that there is a large petroleum endowment in North, Central, and South America that will last for several decades and will help to contribute significantly to the energy needs of these regions. It is recommended to actively pursue research and development of this endowment.
Extraction of Dissolved Methane in Brines by CO2 Injection: Implication for CO2 Sequestration
Authors: Taggart Ian 
Published: October 2010

Summary
The solubility of carbon dioxide (CO2) in underground saline formations is considered to offer significant long-term storage capability to effectively sequester large amounts of anthropogenic CO2. Unlike enhanced oil recovery (EOR), geosequestration relies on longer time scales and involves significantly greater volumes of CO2. Many geosequestration studies assume that the initial brine state is one containing no dissolved hydrocarbons and, therefore, apply simplistic two-component solubility models starting from a zero dissolved-gas state. Many brine formations near hydrocarbons, however, tend to be close to saturation by methane (CH4). The introduction of excess CO2 in such systems results in an extraction of the CH4 into the CO2-rich phase, which, in turn, has implications for monitoring of any sequestration project and offers the possibly additional CH4 mobilization and recovery.
Spoolable Connector Allows Coiled-Tubing Operations Offshore India
Authors: Effiong G.. , Dean G.. , Nayak S.. , Satyarthi R.S.. S. 
Published: October 2010

Summary
Available footprint on offshore platforms (Fig. 1) can be a significant challenge for coiled-tubing (CT) operations. Many times, platform limitations require that a smaller CT unit be deployed for work that would be faster and easier operationally with CT of a larger diameter. Often the platform's crane capacity dictates the size of CT used, which in turn reduces the working envelope of the CT.
Some wells offshore India are completed horizontally and require intervention using larger sizes of CT in order to gain horizontal reach and manipulate sliding sleeves. When CT is used for these operations, the weight of the CT reel itself is critical to the effectiveness of the overall operation and requires proper management. Traditional methods of managing/reducing CT-reel weight involve spooling the CT string from a boat to the platform or joining CT sections by butt welding on the platform. Bringing the required length of CT onboard in two or more sections and joining them with a spoolable connector provides significant benefits over the traditional methods. The use of just one spoolable connector can reduce the maximum CT-reel lifting weight by typically 30 to 40% while increasing the CT size by one or two gauge sizes.
This paper describes the results of a feasibility study performed to address typical challenges and presents actual case histories in which a spoolable connector was used to connect two CT strings. Required equipment was built and mobilized so that two separate strings could be joined on the platform with the aid of a connecting jig. Several trips were performed safely without the need to change the spoolable connector. Specific benefits of the spoolable connector over the traditional methods are explained. Methods to monitor the usable life of the spoolable connector while tripping in and out of the well (Fig. 2) will also be discussed, as well as new developments currently under way.
Experimental and Numerical Modeling of Three-Phase Flow Under High-Pressure Air Injection
Authors: Niz-Velásquez E. , Moore R.G.. G. , van Fraassen K.C.. C. , Mehta S.A.. A. , Ursenbach M.G.. G. 
Published: October 2010

Summary
In this paper, an improved characterization of three-phase flow under high-pressure-air-injection (HPAI) conditions was achieved on the basis of experimental results and numerical reservoir simulation.
A three-phase coreflood experiment was conducted at reservoir conditions, using 37°API stock-tank oil, an 84% nitrogen and 16% carbon dioxide flue-gas mixture, and 3% potassium chloride brine. The aim of the test was to evaluate the effects that the highly liquid-saturated front produced by the thermal reactions has on the mobility of each phase. Departing from connate-water saturation and reservoir pressure and temperature, sequential injection of water, gas, and oil was carried out, followed by a final gasflood to residual liquid saturation. Other two- and three-phase tests performed on this rock specimen were published elsewhere (Niz-Velásquez et al. 2009). Numerical history matching was employed to determine oil/water and liquid/gas relative permeability (kr) curves for both imbibition and drainage cases. A combustion-tube (CT) test was simulated using conventional kr curves and a set that included hysteresis. The degree of hysteresis observed during the coreflood test was maintained for the CT simulation.
History matching of the coreflood showed that kr to the gas phase is much smaller during liquid reimbibition than during drainage. The use of gas-phase hysteresis for the CT test allows for a better matching of liquid volumes and pressure drop. Analysis of the simulated data suggests that the reduction in gas-phase mobility encourages an early increase in the oil rate, which is more consistent with experimental data than what is predicted by a model with conventional kr. The analysis also reveals that water distilled below the saturated steam temperature plays an important role in the increase of liquid saturation and oil mobilization.
The improved characterization of relative permeability considering gas-phase hysteresis for simulating HPAI enhances the predictive capability of available commercial simulators, providing a more certain method to evaluate the technical and economical feasibility of a project. The ability to predict an early increase in oil rate, consistent with experimental observations, results in improved economics for the project.
Use of Biodiesel as an Additive in Thermal Recovery of Heavy Oil and Bitumen
Authors: Babadagli Tayfun , Er Vahapcan , Naderi Khosrow , Burkus Zvonko , Ozum Baki 
Published: October 2010

Summary
Bitumen extraction in oil sands-ore water slurry systems was studied by using lipids and lipid derivatives such as biodiesel (BD) as surfactant additive to promote bitumen recovery efficiency. Performance of BDs (i.e., canola and tall oil, a by-product of pulp mills using the bleached Kraft process) fatty acids methyl ester and food-grade fatty acids monoglycerides were evaluated as surfactant additives. Experimental findings suggest that BDs such as fatty acids methyl esters could also be used as surfactant additives to increase the efficiency of bitumen recovery in thermal in-situ processes such as steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) processes. The required dosage for the surfactant additive is about 0.1% of bitumen by mass. Also, interfacial tension measurements between bitumen and process water (YB,W) and BD and process water (YBD,W) support the surfactant behavior of BD.
Optimization of Liquid and Gas Flow Rates for Aerated Drilling Fluids Considering Hole Cleaning for Vertical and Low Inclination Wells
Authors: Ozbayoglu Evren M. 
Published: October 2010

Summary
Underbalanced drilling (UBD) is one of the most widely used technologies preferred in depleted and/or low-pressured formations. In order to achieve underbalanced conditions, drilling fluids are usually gasified. Major drilling fluids preferred during UBD are pure gas, gas-liquid mixtures, and foams. This study is focused on gas-liquid mixtures. As the gas is introduced, the behaviour of the drilling fluid becomes hard to explain for many reasons. First of all, gas is compressible and physical properties of gas are very sensitive to changes in pressure and temperature. Second, a multiphase flow phenomenon arises. When there is multiphase flow, flow patterns should be considered. It is known that there is a difficulty to predict hydraulic behaviour of gas-liquid mixtures owing to this flow pattern dependence. During a drilling operation, one of the parameters that should be considered is hole cleaning. Hole cleaning is a challenging task even for a single-phase drilling fluid. Moreover, there is still a lack of information about how the cuttings are transported when gas-liquid mixtures are used as drilling fluids. Flow-rate optimization during UBD operations for liquid and gas phases are usually conducted based on formation pressures only. However, considering only this criterion as the optimization objective is misleading and may cause serious problems during the drilling operation. In this study, gas and liquid flow rates during UBD operations are conducted not only based on formation pressures, but also based on effective hole cleaning. It is assumed that liquid phase is the major contributor for cuttings transport, and gas phase is only influencing the bottomhole pressure. A mechanistic model is introduced for estimating the hydraulic behaviour of gas-liquid mixture drilling fluids under different flow patterns. Based on the bottomhole pressure and effective hole cleaning point of view, an algorithm is proposed for estimation of the optimum required flow rates for liquid and gas phases based on the introduced mechanistic model. Also, the model predicts the required backpressure that has to be applied.
Optimal Parametric Design for Water-Alternating-Gas (WAG) Process in a CO2-Miscible Flooding Reservoir
Authors: Chen S. , Li H. , Yang D. , Tontiwachwuthikul P. 
Published: October 2010

Summary
A pragmatic method has been developed to efficiently design the production-injection parameters to optimize the water-alternating-gas (WAG) performance in a field-scale CO2-miscible flooding project. The net present value (NPV) is selected as the objective function, while the controlling variables are chosen to be the injection rates, ratios of gas slug size to water slug size (WAG ratio) and cycle time (i.e., the injection time for each gas or water slug) for the injectors and bottomhole pressures (BHPs) for the producers. A hybrid technique, which integrates the orthogonal array (OA) and Tabu technique into the genetic algorithm (GA), is then developed and employed to determine the optimum WAG production-injection parameters. Sensitivity analysis of the WAG parameters on oil recovery is conducted and a field case is finally presented to demonstrate the successful application of the newly developed technique.
Renal, Ocular, and Neuromuscular Involvements in Patients with CLDN19 Mutations
Authors: Faguer Stanislas , Chauveau Dominique , Cintas Pascal , Tack Ivan , Cointault Olivier , Rostaing Lionel , Vargas-Poussou Rosa , Ribes David 
Published: October 2010

Summary

Background and objectives
The objective of this study was to describe the renal and extrarenal findings in patients with recessively inherited familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) associated with CLDN19 mutations.

Design, setting, participants, & measurements
Medical records of three patients from two French unrelated families with CLDN19 mutations were retrospectively examined.

Results
Direct sequencing of CLDN19 identified a known variant (p.Gly20Asp) in all patients and a new missense mutation (p.Val44Met) in one (compound heterozygous). The patients' renal phenotype closely mimicked CLDN16-related nephropathy: low serum Mg2+ (<0.65 mmol/L) despite oral supplementation, hypercalciuria partly thiazide-sensitive, and progressive renal decline with ESRD reached at age 16 and 22 years in two individuals. Primary characteristics (failure to thrive, recurrent urinary tract infections, or abdominal pain), age at onset (0.8 to 16 years), and rate of renal decline were highly heterogeneous. Ocular involvement was identified in all patients, although two patients did not have visual loss. Additionally, exercise intolerance with pain, weakness, and electromyographical alterations mimicking a Ca2+/K+ channelopathy (pattern V) were observed in two of three individuals. These features persisted despite the normalization of serum K+ and Mg2+ after renal transplantation.

Conclusions
Ocular manifestations, even subtle, and exercise intolerance mimicking mild to moderate periodic paralysis are two symptoms that need to be searched for in patients with FHHNC and may indicate CLDN19 mutations.
Role of Residual Renal Function in Phosphate Control and Anemia Management in Chronic Hemodialysis Patients
Authors: Penne E. Lars , van der Weerd Neelke C. , Grooteman Muriel P.C. , Mazairac Albert H.A. , van den Dorpel Marinus A. , Nubé Menso J. , Bots Michiel L. , Lévesque Renée , ter Wee Piet M. , Blankestijn Peter J. 
Published: October 2010

Summary

Background and objectives
There is increasing awareness that residual renal function (RRF) has beneficial effects in hemodialysis (HD) patients. The aim of this study was to investigate the role of RRF, expressed as GFR, in phosphate and anemia management in chronic HD patients.

Design, setting, participants, & measurements
Baseline data of 552 consecutive patients from the Convective Transport Study (CONTRAST) were analyzed. Patients with a urinary output ≥100 ml/24 h (n = 295) were categorized in tertiles on the basis of degree of GFR and compared with anuric patients (i.e., urinary output <100 ml/24 h, n = 274). Relations between GFR and serum phosphate and erythropoiesis-stimulating agent (ESA) index (weekly ESA dose per kg body weight divided by hematocrit) were analyzed with multivariable regression models.

Results
Phosphate levels were between 3.5 and 5.5 mg/dl in 68% of patients in the upper tertile (GFR > 4.13 ml/min per 1.73 m2), as compared with 46% in anuric patients despite lower prescription of phosphate-binding agents. Mean hemoglobin levels were 11.9 ± 1.2 g/dl with no differences between the GFR categories. The ESA index was 31% lower in patients in the upper tertile as compared with anuric patients. After adjustments for patient characteristics, patients in the upper tertile had significantly lower serum phosphate levels and ESA index as compared with anuric patients.

Conclusions
This study suggests a strong relation between RRF and improved phosphate and anemia control in HD patients. Efforts to preserve RRF in HD patients could improve outcomes and should be encouraged.
Contribution of Residual Function to Removal of Protein-Bound Solutes in Hemodialysis
Authors: Marquez Ilian O. , Tambra Shouieb , Luo Frank Y. , Li You , Plummer Natalie S. , Hostetter Thomas H. , Meyer Timothy W. 
Published: October 2010

Summary

Background and objectives
This study evaluated the contribution of residual function to the removal of solutes for which protein binding limits clearance by hemdialysis.

Design, setting, participants, & measurements
Solute concentrations were measured in 25 hemodialysis patients with residual urea clearances ranging from 0.1 to 6.2 ml/min per 1.73 m2. Mathematical modeling assessed the effect of residual function on time-averaged solute concentrations.

Results
Dialytic clearances of the protein-bound solutes p-cresol sulfate, indoxyl sulfate, and hippurate were reduced in proportion to the avidity of binding and averaged 8 ± 2, 10 ± 3, and 44 ± 13% of the dialytic urea clearance. For each bound solute, the residual clearance was larger in relation to the residual urea clearance. Residual kidney function therefore removed a larger portion of each of the bound solutes than of urea. Increasing residual function was associated with lower plasma levels of p-cresol sulfate and hippurate but not indoxyl sulfate. Wide variation in solute generation tended to obscure the dependence of plasma solute levels on residual function. Mathematical modeling that corrected for this variation indicated that increasing residual function will reduce the plasma level of each of the bound solutes more than the plasma level of urea.

Conclusions
In comparison to urea, solutes than bind to plasma proteins can be more effectively cleared by residual function than by hemodialysis. Levels of such solutes will be lower in patients with residual function than in patients without residual function even if the dialysis dose is reduced based on measurement of residual urea clearance in accord with current guidelines.
Coffee and Caffeine Consumption in Relation to Sex Hormone–Binding Globulin and Risk of Type 2 Diabetes in Postmenopausal Women
Authors: Goto Atsushi , Song Yiqing , Chen Brian H. , Manson JoAnn E. , Buring Julie E. , Liu Simin 
Published: October 2010

OBJECTIVE
Coffee consumption has been inversely associated with type 2 diabetes risk, but its mechanisms are largely unknown. We aimed to examine whether plasma levels of sex hormones and sex hormone–binding globulin (SHBG) may account for the inverse association between coffee consumption and type 2 diabetes risk.

RESEARCH DESIGN AND METHODS
We conducted a case-control study nested in the prospective Women's Health Study (WHS). During a median follow-up of 10 years, 359 postmenopausal women with newly diagnosed type 2 diabetes were matched with 359 control subjects by age, race, duration of follow-up, and time of blood draw.

RESULTS
Caffeinated coffee was positively associated with SHBG but not with sex hormones. Multivariable-adjusted geometric mean levels of SHBG were 26.6 nmol/l among women consuming ≥4 cups/day of caffeinated coffee and 23.0 nmol/l among nondrinkers (P for trend = 0.01). In contrast, neither decaffeinated coffee nor tea was associated with SHBG or sex hormones. The multivariable-adjusted odds ratio (OR) of type 2 diabetes for women consuming ≥4 cups/day of caffeinated coffee compared with nondrinkers was 0.47 (95% CI 0.23–0.94; P for trend = 0.047). The association was largely attenuated after further adjusting for SHBG (OR 0.71 [95% CI 0.31–1.61]; P for trend = 0.47). In addition, carriers of rs6259 minor allele and noncarriers of rs6257 minor allele of SHBG gene consuming ≥2 cups/day of caffeinated coffee had lower risk of type 2 diabetes in directions corresponding to their associated SHBG.

CONCLUSIONS
Our findings suggest that SHBG may account for the inverse association between coffee consumption and type 2 diabetes risk among postmenopausal women.