bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunologic Features of Cornelia de Lange Syndrome
Authors: Jyonouchi Soma , Orange Jordan , Sullivan Kathleen E. , Krantz Ian , Deardorff Matthew 
Published: July 2013

OBJECTIVES:
Cornelia de Lange syndrome (CdLS) is a genetic syndrome with multisystem abnormalities. Infections are a significant cause of morbidity and mortality. The goals of our study were to identify the frequency and types of infections in CdLS and to determine if underlying immunodeficiency contributes to the clinical spectrum of this syndrome.

METHODS:
We assessed infectious histories in 45 patients with CdLS and evaluated conventional immunologic screening tests in 27 patients. Among these 27 subjects, additional phenotypic enumeration of T-cell subsets, expression of activation markers in T cells, and production of cytokines in response to T-cell stimulants were studied in 12 CdLS subjects compared with 12 normal case control subjects.

RESULTS:
Recurrent infections were reported at high frequency in CdLS patients and included chronic ear infections (53%), chronic viral respiratory infections (46%), pneumonia (42%), sinus infections (33%), oral candidiasis (13%), sepsis (6%), and bacterial skin infections (4%). Full immune evaluation in 27 subjects led to identification of 9 cases of antibody deficiency syndrome in patients with severe forms of CdLS. Subjects with CdLS had decreased percentages of T regulatory cells and T follicular helper cells compared with normal control subjects (P &lt; .05).

CONCLUSIONS:
This study identified for the first time a high frequency of antibody deficiency in CdLS subjects, indicating a critical need for screening and management of immunodeficiency in CdLS patients with a history of well-documented severe or recurrent infections. Furthermore, our results indicate that impaired T-cell populations may be associated with antibody deficiency in CdLS.
Epidemiology and Trends of Necrotizing Enterocolitis in Sweden: 1987–2009
Authors: Ahle Margareta , Drott Peder , Andersson Roland E. 
Published: July 2013

OBJECTIVE:
To investigate temporal, seasonal, and geographic variations in the incidence of necrotizing enterocolitis (NEC) and its relation to early infant survival in the Swedish population and in subgroups based on gestational age, birth weight, and gender.

METHODS:
In the Swedish birth cohort of 1987 through 2009 all children with a diagnosis of NEC were identified in the National Patient Register, the Swedish Medical Birth Register, and the National Cause of Death Register. NEC incidence, early mortality, and seasonality were analyzed with descriptive statistics, Poisson regression, and auto regression.

RESULTS:
The overall incidence of NEC was 3.4 in 10 000 live births, higher in boys than in girls (incidence rate ratio 1.22, 95% confidence interval 1.06–1.40, P = .005), with a peak in November and a trough in May, and increased with an average of ∼5% a year during the study period. In most subgroups, except the most immature, an initial decrease was followed by a steady increase. Seven-day mortality decreased strongly in all subgroups over the entire study period (annual incidence rate ratio 0.96, 95% confidence interval 0.95–0.96, P &lt; .001). This was especially marked in the most premature and low birth weight infants.

CONCLUSIONS:
After an initial decrease, the incidence of NEC has increased in Sweden during the last decades. An association with the concurrent dramatically improved early survival seems likely.
Enhanced Oil Recovery by Chemical Flooding from the Biostromal Carbonate Reservoir
Authors: Zhu Youyi , Wang Zhe , Wu Kangyun , Hou Qingfeng , Long Hang 
Published: July 2013

Abstract
Lab study of chemical EOR for the carbonate reservoir was performed through core characterization, chemical formula screening, surfactant adsorption losses experiments and oil displacement core flooding tests of chemical flooding.
The research results lay the foundation of future pilot tests for chemical combination flooding applying to carbonate reservoirs.
Core characterization by scanning electron microscope and mercury injection capillary pressure experiment prove that there are plenty micropores and a few emposieu within rock, porosity of formation cores is relatively high but permeability is low, the reservoir lithology belonged to typical biostromal carbonate reservoir and the heterogeneity is severe. Chemical flooding formula was investigated by polymer and surfactant screening tests. Salt tolerant polymers including STARPAM and KYPAM showed good viscosifying performances than conventional polymer when prepared with formation water. Amphoteric surfactant AS-13 and anion-nonionic surfactant SPS1708 were selected and ultra-low interfacial tension between crude oil and formation water can be obtained in alkali-surfactant-polymer (ASP) and alkali free surfactant-polymer (SP) systems. Adsorption losses of surfactants on core sample showed that the dynamic adsorption losses of surfactant AS-13 and SPS1708 were 0.46mg/g and 0.37mg/g respectively. Core flooding tests of chemical flooding proved that more than 17~18% incremental oil recovery over water flooding could be obtained with ASP (0.6wt% Na3PO4 + 0.3wt% surfactant + 1000ppm polymer) or SP (0.3wt% surfactant + 1000ppm polymer) flooding. The effect of both ASP and SP flooding was better than that of surfactant flooding.
The experimental results are considered to be technical feasibility and confirm the effectiveness of chemical EOR methods especially the SP flooding for the biostromal carbonate reservoir, which may present further understanding for chemical EOR field application in carbonate reservoirs.
Laboratory Investigation of the Effect of Microbial Metabolite on Crude Oil-Water Interfacial Tension Under Reservoir Conditions
Authors: Wei Xiaofang , Liu Keyu , Li Dongmei 
Published: July 2013

Abstract
The mechanisms of Microbial Enhanced Oil Recovery (MEOR) are generally thought to be through oil biodegradation, production of biosurfactants, biogases, low molecular acids and biopolymers by microbes. The first four processes contribute to Interfacial Tension (IFT) reduction while the final one to plugging high permeability zones. Microbes can produce diverse metabolites thereby modifying the oil-water IFT in an oil reservoir. This study attempts to investigate the effect of microbial metabolites on the oil viscosity and IFT under reservoir P/T conditions.
A reservoir fluid with 20% crude oil and 80% formation water was treated with indigenous microbes for 21 days under anaerobic condition using molasses (5%) as nutrients. The microbially treated and the un-treated oils were analysed geochemically by using Gas Chromatography-Mass Spectrometer (GC-MS). The oil density, viscosity and the oil-water IFT of both the un-treated and bio-treated oils were measured under reservoir P/T conditions.
The analytical results indicated that there were no significant difference in chemical compositions and densities among different oil samples, suggesting little or none microbial biodegradation present. The effect of biogases and low molecular acids was excluded because of the measurement methodology used.
In contrast to the un-treated oil, the IFT of the bio-treated crude oil was found to be reduced from the un-treated 7.2 to 3.7×10-3 mN/m, a 48% reduction. The oil viscosity of the bio-treated crude oil was decreased by 50%. The viscosity and IFT reduction might be primarily due to the microbial metabolites (biosurfactants) produced, which may play a key role in altering the oil-water interface. Macro-micro emulsification was also observed at the oil-water interface. It is concluded that microbial metabolites could potentially reduce the oil viscosity (via emulsification) and improve the crude oil-water IFT under reservoir P/T conditions.
A Study of Three Phase Relative Permeability and Hysteresis in Water Alternating Gas (WAG) Injection
Authors: Arogundade O.. , Shahverdi H.. , Sohrabi M.. 
Published: July 2013

AbstractVarious techniques of Enhanced Oil Recovery (EOR) exist and amongst them water and gas injection are the most widely used. It has been shown that combining water and gas injection in a WAG (water alternating gas) scheme can result in additional oil recovery. Interest in WAG injection has increasingly grown in recent times with many reservoirs around the world now under WAG injection.Numerical simulation of WAG requires reliable three-phase relative permeability and hysteresis data which are normally obtained from models available in commercial simulators. This paper utilizes core-flood experimental data from literature to investigate validity of these models.The findings from this study provide evidence that different three-phase relative permeability models were found to behave differently giving varying recovery factors in a WAG simulation scheme. While the effect of irreversible hysteresis was studied, it was observed here that imbibition (stage I) and drainage (stage II) processes gave results that deviated from conventional hysteresis. Simulations were run with and without hysteresis for different three phase relative permeability models with different effects observed for the recovery factor.The results of this work show that a good understanding of the three phase relative permeability model in use is very important for a more robust reservoir simulation model. Also, the effect of irreversible hysteresis in WAG injection should be adequately modelled in order to obtain reliable results. Lastly, the results reveal the importance of optimum WAG ratio for maximizing oil recovery by preventing a gas tongue forming at the top of the reservoir and a water tongue forming at the bottom of the reservoir.
Surfactant Polymer (SP) Flooding Pilot Test on Offshore Heavy Oil Field in Bohai Bay, China
Authors: Kang Xiaodong , Zhang Jian 
Published: July 2013

AbstractEOR technology has been applied on many projects globally with variable success. It shows great potential for offshore heavy oil with oil recovery low in life span of platform (general less than 30% by water flooding). About 60-70% oil is remained in the formation after water flooding, and for offshore heavy oil reservoir, more oil (about 80%) is remained by the end of the platform life.[1] It becomes more important to achive high recovery before abandoning the platform and the oilfields with lots of oil left in reservoir. With recovery increasment of 5-10% by EOR methods, the reserve will increase greatly, which means an order of magnitude of hundreds of million-tons oilfield is discovered without increase any exploration investment.Surfactant-polymer (SP) flooding was a potential enhanced oil recovery (EOR) technology that was more powerful than the polymer flooding. And it was test or applied successfully in some high or extra-high WCT onshore oilfields of Shengli oilfields (SINOPEC), Daqing oilfields (CNPC) in china. The paper presents a filed EOR test case of offshore heavy oilfield oilfield by SP.
Development of a Phase Behavior Numerical Model for Evaluating Thermal Assisted Processes with Solvents in Heavy Oil Recovery
Authors: Trigos-Becerra Erika-Margarita , Vega-Moreno Sandra-Milena , Rodríguez-Paredes Edwin , Rivera-De-La-Ossa Juan-Eduardo , Naranjo-Suárez Carlos-Eduardo 
Published: July 2013

Abstract
In the design phase of a pilot project for Enhanced Oil Recovery, more commonly referred as EOR, is important the prediction of the results by either numerical simulation or analytical modeling. Those tools are useful for the determination of the minimum conditions necessary for the implementation of the recovery method as well as to determine the feasibility of the project.
The more complexity degree of the process the more accurate the fluid model require. For example, to represent the steam injection process, any viscosity curve representing the behavior of known relative permeability curves with temperature is enough. Moreover, Enhanced Oil Recovery-EOR methods as in situ combustion, gas injection or miscible solvent injection (alone or assisted vapor) fluid require a more complex model representing all consistently appropriate physical-chemical changes that occur in the crude blend with a foreign agent.
The development of a numerical model of fluid to represent of injection processes of steam assisted with solvent. This model requires a previous experimental evaluation, which should include PVT characterization of solvent and oil, viscosity curves and miscibility conditions. Once they are developed in the lab tests, it should load the information obtained in a fluid modeling software, where the dead oil, live oil, blend live oil and solvent must be adjusted using equations of state. In this case, the equation of state that best represents the behavior of heavy oil and solvent is Peng Robinson. The most important matching parameters are: critical temperature and critical pressure, although it should be given special treatment with the binary interaction coefficients. Finally be obtain the equilibrium constants and viscosity tables, maintaining minimum allowable error of less than 5% compared to the laboratory data, which is important to reduce the uncertainty associated with the behavior of fluids.
This paper presents a detailed methodology to represent numerically the behavior of fluids in a steam injection process enhanced with solvent in heavy oil reservoirs, applied to a Colombian field.
Microemulsion Flow in Porous Media: Implications for Alkaline-Surfactant-Polymer Flooding
Authors: Humphry K. J. , Van Der Lee M.. , Ineke E. M. , Van Batenburg D. W. , Southwick J. G. 
Published: July 2013

AbstractWorkflows to assess the technical and economic suitability of an enhanced oil recovery (EOR) technique for a particular field generally involve laboratory testing, such as core flooding experiments, and field-scale reservoir modelling. When building field scale models and interpreting laboratory experiments it is important to understand the flow properties of all phases present.Alkali-surfactant-polymer flooding (ASP) is an EOR technique under consideration for a number of Malaysian oil fields. In ASP flooding, surface-active molecules decrease the interfacial tension between water and crude oil, increasing the capillary number, and recovering oil trapped in the reservoir pores. The ultra-low interfacial tensions needed for ASP flooding occur when the surface active molecules are equally soluble in the brine and oil phases. Under these conditions, in addition to the brine and oil phases, a third thermodynamically stable phase is formed. This third phase is known as a microemulsion. While the flow properties of crude oil and polymer-enriched brine are well understood, little has been done to characterize the microemulsion phase, particularly with respect to rheology in porous media.Here, preliminary measurements of microemulsion rheology are presented. Large volumes of microemulsion, with and without polymer, are generated using model alkali-surfactant (AS) and alkali-surfactant-polymer (ASP) systems. These microemulsions are studied using conventional shear rheology. The viscosities measured using a conventional shear rheometer indicate microemulsion viscosities higher than either the AS(P) solution or decane from which they are comprised. Additionally, an in situ, or apparent, viscosity is recovered from core flooding experiments in Berea sandstone, where pressure drop across the core is recorded as a function of the flow rate of the microemulsion through the core. In situ viscosity measurements in Berea sandstone indicate apparent viscosities 1.5 to 6 times larger than those measured in a conventional shear rheometer. The implication of these results for ASP flooding is discussed.
Pelican Lake Field: First Successful Application of Polymer Flooding in a Heavy Oil Reservoir
Authors: Delamaide Eric , Zaitoun Alain , Renard Gérard , Tabary René 
Published: July 2013

Abstract
The Pelican Lake heavy oil field located in northern Alberta (Canada) has had a remarkable history since its discovery in the early 1970s. Initial production using vertical wells was poor because of the thin (less than 5m) reservoir formation and high oil viscosity (600 to over 40,000cp). The field began to reach its full potential with the introduction of horizontal drilling and was one of the first fields worldwide to be developed with horizontal wells. Still, with primary recovery less than 10% and several billion barrels of oil in place, the prize for EOR is large.
Initially, polymer flooding had not been considered as a viable EOR technology for Pelican Lake due to the high viscosity of the oil, until the idea came of combining it with horizontal wells. A first – unsuccessful – pilot was implemented in 1997 but the lessons drawn from that failure were learnt and a second pilot met with success in 2006. The response to polymer injection in this pilot was excellent, oil rate climbing from 43bopd to over 700bopd and remaining high for over 6 years now; the water-cut has generally remained below 60%.
This paper presents the history of the field then focuses on the polymer flooding aspects. It describes the preparation and results of the two polymer flood pilots as well as the extension of the flood to the rest of the field (currently in progress).
Polymer flooding has generally been applied in light or medium gravity oil and even today, standard industry screening criteria limit its use to viscosities up to 150cp only. Pelican Lake is the first successful application of polymer flooding in much higher viscosity oil (1,000-2,500cp) and as such, it opens a new avenue for the development of heavy oil resources that are not accessible to thermal methods.
Application of Digital Rock Technology for Chemical EOR Screening
Authors: Koroteev D.. , Dinariev O.. , Evseev N.. , Klemin D.. , Safonov S.. , Gurpinar O.. , Berg S.. , vanKruijsdijk C.. , Myers M.. , Hathon L.. , de Jong H.. , Armstrong R.. 
Published: July 2013

Abstract
Fast and reliable EOR process selection is a critical step in any EOR project. The digital rock (DR) approach jointly developed by Shell and SLB is aimed to be the smallest scale yet advanced EOR Pilot technology. In this document, we describe the application of DR technology for screening of different EOR mechanisms at pore-scale focused to enhance recovery from a particular reservoir formation. For EOR applications DR brings unique capabilities as it can fully describe different multiphase flow properties at different regimes.
The vital part of the proposed approach is the high-efficient pore-scale simulation technology called Direct Hydrodynamics (DHD) Simulator. DHD is based on a density functional approach applied for hydrodynamics of complex systems. Currently, DHD is benchmarked against multiple analytical solutions and experimental tests and optimized for high performance (HPC) computing. It can handle many physical phenomena: multiphase compositional flows with phase transitions, different types of fluid-rock and fluid-fluid interactions with different types of fluid rheology. As an input data DHD uses 3D pore texture and composition of rocks with distributed micro-scale wetting properties and pore fluid model (PVT, rheology, diffusion coefficients, and adsorption model). In a particular case, the pore geometry comes from 3D X-ray microtomographic images of a rock sample. The fluid model is created from lab data on fluid characterization. The output contains the distribution of components, velocity and pressure fields at different stages of displacement process. Several case studies are demonstrated in this work and include comparative analysis of effectiveness of applications of different chemical EOR agents performed on digitized core samples.
Estimation of Parameters for the Simulation of Foam Flow through Porous Media: Part 3; Non-Uniqueness, Numerical Artifact and Sensitivity
Authors: Ma Kun , Farajzadeh Rouhi , Lopez-Salinas Jose L. , Miller Clarence A. , Biswal Sibani Lisa , Hirasaki George J. 
Published: July 2013

Abstract
In the absence of oil in the porous medium, the STARS™ foam model has three parameters to describe the foam quality dependence, fmmob, fmdry, and epdry. Even for a specified value of epdry, two pairs of values of fmmob and fmdry can sometimes match experimentally measured ftg and μtfoam,app. This non-uniqueness can be broken by limiting the solution to the one for which fmdry &lt;Sttw. Additionally, a three-parameter search is developed to simultaneously estimate the parameters fmmob, fmdry, and epdry that fit the transition foam quality and apparent viscosity. However, a better strategy is to conduct and match a transient experiment in which 100% gas displaces surfactant solution at 100% water saturation. This transient foam quality scans the entire range of fractional flow and the values of the foam parameters that best match the experiment can be uniquely determined. Finally, a three-parameter fit using all experimental data of apparent viscosity versus foam quality is developed.
The numerical artifact of pressure oscillations in simulating this transient foam process is investigated by comparing finite difference algorithm with method of characteristics. Sensitivity analysis shows that the estimated foam parameters are very dependent on the parameters for the water and gas relative permeability. In particular, the water relative permeability exponent and connate water saturation are important.
Accelerated Surfactant Selection for EOR Using Computational Methods
Authors: Buijse Marten , Tandon Kunj , Jain Shekhar , Jain Amit , Handgraaf Jan-Willem , Fraaije Johannes G. 
Published: July 2013

AbstractSurfactant formulations are extensively being developed in the oil industry for Enhanced Oil Recovery (EOR) applications. Surfactants suitable for EOR will form an oil-brine microemulsion (µE) with ultra-low interfacial tension (IFT), necessary for high recovery factors. Experimental screening of surfactants, to identify suitable formulations for reservoir conditions, is a laborious and time consuming process. In this paper we demonstrate an alternative, and novel, molecular modeling approach which is suitable for predicting µE properties and calculating optimum conditions. The molecular modeling simulations are based on the recently developed Method of Moments (MoM). The µE physics underlying the MoM is briefly reviewed in this paper.In the MoM the bending properties of the interfacial surfactant film are calculated as moments of the lateral stress profile. At optimum salinity the zeroth and first moments of the lateral stress profile are zero and the IFT will reach a minimum. In addition to optimum salinity, the bending rigidity (stiffness) of the surfactant film is another interesting microstructure property. The bending rigidity determines the oil/brine domain size, solubilization and magnitude of the IFT. The bending rigidity is accessible in the MoM via the saddle-splay modulus κs, which is calculated as the second moment of the lateral stress profile. It is shown in the paper how the shape of the lateral stress profile depends on molecular properties of the surfactant and on salinity.MoM simulations were carried out using the coarse-grained Dissipative Particle Dynamics (DPD) method. This computational approach is highly scalable, while preserving the structural information of chemical components in the system. This makes the method useful while screening the wide design space of possible surfactant-oil-brine combinations. We will discuss the predictive technique and some validation examples of predicting optimum salinity for oil-brine micro-emulsions. We will then demonstrate the effect of surfactant structural parameters like chain length, cosolvent etc. on the optimum salinity of the microemulsions.