bluuebunny/crossref_metadata_2025 huggingface dataset:
Smchd1 regulates a subset of autosomal genes subject to monoallelic expression in addition to being critical for X inactivation
Authors: Mould Arne W , Pang Zhenyi , Pakusch Miha , Tonks Ian D , Stark Mitchell , Carrie Dianne , Mukhopadhyay Pamela , Seidel Annica , Ellis Jonathan J , Deakin Janine , Wakefield Matthew J , Krause Lutz , Blewitt Marnie E , Kay Graham F
Published: July 2013

Background

Smchd1 is an epigenetic modifier essential for X chromosome inactivation: female embryos lacking Smchd1 fail during midgestational development. Male mice are less affected by Smchd1-loss, with some (but not all) surviving to become fertile adults on the FVB/n genetic background. On other genetic backgrounds, all males lacking Smchd1 die perinatally. This suggests that, in addition to being critical for X inactivation, Smchd1 functions to control the expression of essential autosomal genes.

Results

Using genome-wide microarray expression profiling and RNA-seq, we have identified additional genes that fail X inactivation in female Smchd1 mutants and have identified autosomal genes in male mice where the normal expression pattern depends upon Smchd1. A subset of genes in the Snrpn imprinted gene cluster show an epigenetic signature and biallelic expression consistent with loss of imprinting in the absence of Smchd1. In addition, single nucleotide polymorphism analysis of expressed genes in the placenta shows that the Igf2r imprinted gene cluster is also disrupted, with Slc22a3 showing biallelic expression in the absence of Smchd1. In both cases, the disruption was not due to loss of the differential methylation that marks the imprint control region, but affected genes remote from this primary imprint controlling element. The clustered protocadherins (Pcdhα, Pcdhβ, and Pcdhγ) also show altered expression levels, suggesting that their unique pattern of random combinatorial monoallelic expression might also be disrupted.

Conclusions

Smchd1 has a role in the expression of several autosomal gene clusters that are subject to monoallelic expression, rather than being restricted to functioning uniquely in X inactivation. Our findings, combined with the recent report implicating heterozygous mutations of SMCHD1 as a causal factor in the digenically inherited muscular weakness syndrome facioscapulohumeral muscular dystrophy-2, highlight the potential importance of Smchd1 in the etiology of diverse human diseases.
Small bowel feeding and risk of pneumonia in adult critically ill patients: a systematic review and meta-analysis of randomized trials
Authors: Alhazzani Waleed , Almasoud Abdulaziz , Jaeschke Roman , Y Lo Benjamin W , Sindi Anees , Altayyar Sultan , Fox-Robichaud Alison E
Published: July 2013

Introduction

This systematic review and meta-analysis aimed to evaluate the effect of small bowel feeding compared with gastric feeding on the frequency of pneumonia and other patient-important outcomes in critically ill patients.

Methods

We searched EMBASE, MEDLINE, clinicaltrials.gov and personal files from 1980 to Dec 2012, and conferences and proceedings from 1993 to Dec 2012 for randomized trials of adult critically ill patients in the intensive care unit (ICU) comparing small bowel feeding to gastric feeding, and evaluating risk of pneumonia, mortality, length of ICU stay, achievement of caloric requirements, duration of mechanical ventilation, vomiting, and aspiration. Independently, in duplicate, we abstracted trial characteristics, outcomes and risk of bias.

Results

We included 19 trials with 1394 patients. Small bowel feeding compared to gastric feeding was associated with reduced risk of pneumonia (risk ratio [RR] 0.70; 95% CI, 0.55, 0.90; P = 0.004; I2 = 0%) and ventilator-associated pneumonia (RR 0.68; 95% CI 0.53, 0.89; P = 0.005; I2 = 0%), with no difference in mortality (RR 1.08; 95% CI 0.90, 1.29; P = 0.43; I2 = 0%), length of ICU stay (WMD -0.57; 95%CI -1.79, 0.66; P = 0.37; I2 = 0%), duration of mechanical ventilation (WMD -1.01; 95%CI -3.37, 1.35; P = 0.40; I2 = 17%), gastrointestinal bleeding (RR 0.89; 95% CI 0.56, 1.42; P = 0.64; I2 = 0%), aspiration (RR 0.92; 95% CI 0.52, 1.65; P = 0.79; I2 = 0%), and vomiting (RR 0.91; 95% CI 0.53, 1.54; P = 0.72; I2 = 57%). The overall quality of evidence was low for pneumonia outcome.

Conclusions

Small bowel feeding, in comparison with gastric feeding, reduces the risk of pneumonia in critically ill patients without affecting mortality, length of ICU stay or duration of mechanical ventilation. These observations are limited by variation in pneumonia definition, imprecision, risk of bias and small sample size of individual trials.
Evaluating Possibilities of Self-propagating High-temperature Synthesis (SHS) for Substitution of Ge for Si in MoSi2
Authors: Paramasivam Dinesh K , Favier Katia , Rouessac Florence , Ayral Rose-Marie , Viennois Romain , Ravot Didier
Published: July 2013

Self-propagating high-temperature synthesis is used to study materials obtained from a Mo–Si–Ge system. Si1−xGex is known to be one of the most efficient thermoelectrics, but its use is limited by high price and scarcity of germanium, relatively low value of its ZT, and high working temperature. One way to increase its ZT consists of increasing the diffusion of the acoustic phonons by inserting silicide nanoinclusions of MoSi2 inside the Si1−xGex matrix. In this sense it is important to study the Mo(Si1−xGex)2 solid solutions.
Pollinator declines: reconciling scales and implications for ecosystem services
Authors: Bartomeus Ignasi , Winfree Rachael
Published: July 2013

Despite the widespread concern about the fate of pollinators and the ecosystem services they deliver, we still have surprisingly scarce scientific data on the magnitude of pollinator declines and its actual contribution to crop pollination and food security. We use recently published data from northeastern North America to show that studies at both the local and regional scales are needed to understand pollinator declines, and that species-specific responses to global change are broadly consistent across scales. Second, we show that bee species that are currently delivering most of the ecosystem services (i.e. crop pollination) are not among the species showing declining trends, but rather appear to thrive in human-dominated landscapes.
THE PLACE OF FAMILY VALUES IN THE MECHANISM OF PROTECTION OF FAMILY RIGHTS
Authors: Ситкова Ольга , Sitkova Olga
Published: July 2013

The article investigates the relationship issues of public and private interests in building a family. Understood as a legal liability arising from the offense, as well as a threat of standing adverse consequences which arise at the time of occurrence of the family relationship.
Property relations as a core of budget law regulation
Authors: Пауль Алексей , Paul Aleksey
Published: July 2013

The article discusses some issues of property relations in budget law. The author divides the property relations into ownership relations and obligations. Throughout the article the author shows the features of the relations and some problems of their regulation.
Some aspects of determination of mental part of arbitrariness under administrative and criminal law
Authors: Суслопаров Алексей , Susloparov Aleksey , Тарбагаев Алексей , Tarbagaev Aleksey
Published: July 2013

The authors study the norms of administrative and criminal law on arrogation and conclude that there is a necessity of the administrative law improvement in the area of determination of a mental part of arrogation.
LANDFILLED FINE GRAINED MIXED INDUSTRIAL WASTE: METAL RECOVERY
Authors: Spooren Jeroen , Van den Bergh Karlien , Nielsen Peter , Quaghebeur Mieke
Published: July 2013

This study describes the recovery and removal of heavy metals through washing from fine grained materials, recovered from mixed industrial waste (IW) from a landfill site. During this first screening, solutions of different concentrations of three inorganic acids (H2SO4, HCl and HNO3) were tested as possible lixiviants. It has been shown that the extraction of most heavy metals should take place at a well defined pH range in order to avoid dissolution of the matrix material (consisting mainly of Si, Fe, Al, Ca). Furthermore, the buffering effect of the studied material was shown to be stronger for smaller particle sizes, due to larger specific contact surfaces with the lixiviants and differences in composition.
VALORISATION OF STAINLESS STEEL SLAGS AS A HYDRAULIC BINDER
Authors: Kriskova Lubica , Pontikes Yiannis , Zhang Fei , Cizer Özlem , Jones Peter Tom , Van Balen Koen , Blanpain Bart
Published: July 2013

This work is focused on exploring various cold and hot stage treatment paths of stainless steel slag as a tool to improve its hydraulic properties. At a cold stage, mechanical and chemical activation was applied on industrial stainless steel slag; and it was found that both activation methods effectively improve the reactivity of the studied slag. In addition, the detailed investigation of hydration on two major phases, γ – C2S and merwinite, revealed that their hydration resulted in the formation of C – S – H gel, typically formed during the hydration of OPC. Regarding the hot stage treatment, the combination of the chemistry modification with the addition of fly ash at 30 wt. % and fast cooling by means of water quenching resulted in a complete amorphisation of the material. Ultimately, the produced material possessing similar properties to granulated blast furnace slag could be used as a latent hydraulic material in blended cements.
Time, space and place: The Polish Poster School
Authors: Thomas Vicki
Published: July 2013

The Polish posters in The Osborne Robinson Collection form a very distinct group in the archive at The University of Northampton, United Kingdom. They were all created at a particular historic moment between 1945 and 1975. They were collected by the British theatrical set designer, Thomas Osborne Robinson and then given to his local Art School to inspire and influence students. The Polish artists created thought provoking posters to be pasted on the streets of their home cities. Their work continues to be admired and considered internationally significant. They are key to any study of art and design in Poland in the post-war decades, as they worked together in new ways. They were able to create an outlet for individual artistic expression in a period of state control of production. These poster artists belonged to an artistic community working with film-makers, theatre producers and architects. They provided a visual commentary to the physical and social rebuilding of the cultural capital of the Polish nation after World War II. Their work and methods were exported and have relevance and appeal beyond the hoardings of Warsaw. The posters continue to influence on graphic design as they are admired, collected and exhibited internationally.
Homogeneous Ricci solitons
Authors: Jablonski Michael
Published: July 2013

In this work, we study metrics which are both homogeneous and Ricci soliton. If there exists a transitive solvable group of isometries on a Ricci soliton, we show that it is isometric to a solvsoliton. Moreover, unless the manifold is flat, it is necessarily simply-connected and diffeomorphic to ℝ
n
.

In the general case, we prove that homogeneous Ricci solitons must be semi-algebraic Ricci solitons in the sense that they evolve under the Ricci flow by dilation and pullback by automorphisms of the isometry group. In the special case that there exists a transitive semi-simple group of isometries on a Ricci soliton, we show that such a space is in fact Einstein. In the compact case, we produce new proof that Ricci solitons are necessarily Einstein.

Lastly, we characterize solvable Lie groups which admit Ricci soliton metrics.
The Perfection of Bodies: Aristotle’s De Caelo I.1
Authors: Betegh Gábor , Pedriali Francesca , Pfeiffer Christian
Published: July 2013

Abstract: In this paper we give a detailed reconstruction of the first chapter of De Caelo I.1. Aristotle attempts to prove there that bodies are complete and perfect in virtue of being extended in three dimensions. We offer an analysis of this argument and argue that it gives important insight into the role the notion of body plays in physical science. Contrary to other interpretations, we argue that it is an argument about physical, as opposed to mathematical, bodies and that the perfection and completeness of bodies is due to their nature. Moreover, Aristotle heavily relies in his proof on the premise that the number three implies perfection, a view he ascribes to the Pythagoreans. We review the possible sources of this view, as well as its role in Aristotle’s argumentative strategy.
The Shanghai Cooperation Organization, Central Asia, and the Great Powers, an Introduction
Authors: Cabestan Jean-Pierre
Published: July 2013

The Shanghai Cooperation Organization (SCO) appears today as a mature, comprehensive, and inclusive intergovernmental regional organization. However, co-piloted by China and Russia, the SCO’s course still raises many questions about its objectives, priorities, and, more important, its achievements and raison d’être, as well as the enduring rivalries among its members.
Political Tolerance in India
Authors: Widmalm Sten , Oskarsson Sven
Published: July 2013

This study of political tolerance in India reveals a positive correlation between such tolerance and membership in political parties and unions, and living in urban areas. Surprisingly, the study finds no difference in the levels of political tolerance between BJP and Congress (I) supporters, and no connection with education levels.
Labor Conflicts in China
Authors: Chen Feng , Tang Mengxiao
Published: July 2013

Labor conflicts in China can be classified into three types: those over legal rights, over interests, and over the pre-reform entitlements. They have relatively distinguishable bases, claims, framing, and patterns of interaction with the government. The typological classification is useful for understanding the developmental trajectory of labor conflict in China.
Potential Risks of the Russia-North Korea-South Korea Gas Pipeline
Authors: Lee Yusin
Published: July 2013

This paper analyzes the potential risks of the Russia-North Korea-South Korea (RNS) gas pipeline, comparing it with the Russia-Ukraine-Europe (RUE) pipeline. I argue that the possibility of disputes is much higher in the RNS case. Furthermore, I propose that the South Korean government opt to import liquefied natural gas by ship directly from Russia if contingency plans in the case of gas supply disruptions in the RNS pipeline are not available.
Traumatic Eye Injuries From Collapsible Wire Laundry Hampers
Authors: Prickett Adam L. , Salar Senem , Chow Clement C. , Traish Aisha S. , Leiderman Yannek I. , Chau Felix Y. , Kassem Iris S.
Published: July 2013

Two patients presented to the University of Illinois at Chicago Eye and Ear Infirmary within 1 year with penetrating eye injuries caused by similar collapsible cloth and wire laundry hampers. Penetrating eye injuries in children are relatively rare but can result in poor visual outcomes and multiple vision-threatening complications. Both injuries at the University of Illinois resulted in an eye laceration as well as retinal complications similar to those reported with a high velocity injury. This now represents a significant pattern of eye injury and suggests that there exists a nontrivial risk for all children in households with this type of collapsible laundry hamper. Parents should receive a warning of the risks of these hampers.
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 < .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 < .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.
Khat(Catha edulis): Is it “coffee” or “cocaine”?
Authors: Bálint Erika Éva , Falkay György , Bálint Gábor Sándor
Published: July 2013

Regular consumption of khat’s (Catha edulis) fresh leaves seriously affects the health, the social and economic life of the subject. Therefore, it is hazardous both to the individual and the community. According to the latest reports consumption of chat may exert some unknown and unreported gastrointestinal and hepatic effects. On the basis of studies performed by the authors, it seems that khat (cathinone) has no gastric or duodenal ulcerogenic effect. However, it does cause a significant enlargement of the hepatic mitochondria. In addition, a concern arose recently that the profit of illegal traffic of the plant may reach some illegal (terrorist) organisations. Therefore it seems that the so-called “khat-problem” needs further and more effective control. Orv. Hetil., 2013, 154, 1055–1057.
“Dress” makes the neuron – different forms of the extracellular matrix in the vertebrate central nervous system
Authors: Gáti Georgina , Lendvai Dávid
Published: July 2013

Introduction: Extracellular matrix is a key component of most connective tissues. For decades, the presence of this chemically heterogeneous interface has been largely unaddressed or even denied in the central nervous system. It was not until the end of the last century that scientists turned their attention to this enigmatic substance and unravelled its versatile roles in the developing as well as the adult nervous system. Aim: The aim of the authors was to characterize different parts of the human central nervous system: the hippocampus, the lateral geniculate nucleus and the spinal cord. In addition they looked for connections between brain plasticity and extracellular matrix indifferent animal models. Method: The authors used two perfusion fixed human brain and spinal cord samples, 23 further human brain samples for disease-related investigations, 16 adult rat brains and 18 chicken brains of hatchlings, 13 days or three months of age. They visualized the extracellular matrix via lectin- and immunohistochemistry. Results: It was demonstrated that the human central nervous system shows a bewildering phenotypic versatility in its various parts. The human spinal cord harbours perineuronal nets around long-range projection neurons whilst perisynaptic coats are enriched in the dorsal horn. Periaxonal coats protect functional synapses in neurodegeneration. In the rat thalamus, perineuronal matrix is enriched in less plastic territories and develops in accordance with its linked cortical region. In the chicken, perineuronal matrix is well established already at birth and its further development is not functionally dependent. Conclusions: In human, the perineuronal matrix shows a large diversity depending on regional distribution and function. The authors argue that the development and differentiation of extracellular matrix is strongly linked to those of neurons. This observation was based on findings in the domestic chick which exhibits an immediate maturity after hatching as well as on observations in rat thalamic nuclei which reflect the plasticity of their corresponding cortical fields. Orv. Hetil., 2013, 154, 1067–1073.
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

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

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

Various 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

EOR 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

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

Workflows 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

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

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

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 <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

Surfactant 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.
Colloidal Dispersion Gels CDG in Dina Cretáceos Field: From Pilot Design to Field Implementation and Performance
Authors: Castro R. , Maya G. , Sandoval J. , Leon J. , Zapata J. , Lobo A. , Villadiego D. , Perdomo L. , Cabrera F. , Izadi M. , Romero J. , Norman C. , Manrique E.
Published: July 2013

Dina Cretaceous Field is located in the Upper Magdalena Valley (UMV) Basin, Colombia. Dina Field operated by ECOPETROL S.A. (discovered, 1969) started peripheral water in 1985. Based on high water cuts (96%) and recovery factors of 32%, comprehensive enhanced oil recovery (EOR), screening evaluation began late 2009, identified Colloidal Dispersion Gel (CDG) as an optimum EOR method for the field.

This paper summarizes Dina CDG project from the laboratory to the field evaluation. Laboratory studies include basic fluid/fluid evaluation, static adsorption, CDG formulations, slimtube, and coreflood tests. Pilot area selection was based on a comprehensive reservoir and injection/production data analysis, water management, well integrity, among other factors. Pilot design was based on detailed numerical simulations using sector and full field models. CDG pilot design also considered water handling limitations and potential injectivity constraints due to the narrow margin of maximum injection and reservoir pressures, combined with low reservoir permeability (50 to 200 mD).

Peripheral CDG pilot included one injector and three producers. CDG injection began in June 2011 and as of September 2012, approximately 437,000 bbl of CDG have been injected (5% of pilot PV). CDG injection strategy considered a fix polymer concentration of 400 ppm and a variable polymer/crosslinker ratio ranging from 40:1 to 80:1; to control maximum injection pressure. Field results showed an important increase in oil recoveries (oil productivity up to 300%) and reduction of water cut decrease (10%). After 16 months, no polymer had been produced in offset producers. Main operating challenges experienced during the pilot project included; the improvement in water quality and its impact on CDG injectivity which will also be described.

This study provides guidance to successfully design, implement, and evaluate CDG pilot projects and other potential chemical EOR technologies in waterflooded reservoirs. Lessons learned during pilot testing contributed to defining pilot expansion strategies supported by an integrated decision-risk management approach.
Integrated Approach in Deploying Low Salinity Waterflooding
Authors: Sorop T. G. , Suijkerbuijk B. M. , Masalmeh S. K. , Looijer M. T. , Parker A. R. , Dindoruk D. M. , Goodyear S. G. , Al-Qarshubi I. S.
Published: July 2013

Low Salinity Waterflooding (LSF) is an emerging IOR/EOR technology that can improve oil recovery efficiency by lowering the injection water salinity. Field scale incremental oil recoveries are estimated to be up to 6% STOIIP. Being a natural extension of conventional waterflooding (WF), LSF is easier to implement than other EOR methods. However, the processes of screening, designing and executing LSF projects require an increased operator competence and management focus compared to conventional waterflooding. This paper discusses the practical aspects of deploying LSF in fields, focusing on the maturation stages, while highlighting the key success factors.

LSF deployment starts with a portfolio screening against specific surface and subsurface screening criteria to prioritize opportunities. Next, the identified opportunities are run through reservoir conditions SCAL tests to quantify the LSF benefits, while de-risking the potential for any injectivity loss due to clay swelling or deflocculation. Standardized LSF SCAL protocols have been incorporated into the general WF guidelines, so that any suitable new WF project conducts LSF SCAL. For mature waterfloods, this SCAL program provides additional reservoir condition relative permeability data, enabling operating units to optimize well and reservoir management (WRM). The next steps in the process are production forecasting, facilities design, and project economics for the LSF opportunity. The multidisciplinary nature of LSF deployment requires integrated (sub)surface technology teams closely collaborating with R&D and asset teams. The standardization of the facilities design, including cost models, can significantly accelerate the deployment effort.

In Shell, LSF is currently at different stages of deployment around the world and across the whole spectrum of WF projects, from the rejuvenation of brown fields to green field developments (offshore and onshore). The LSF deployment effort is combined with the screening of other EOR technologies, to identify where LSF may be able to unlock additional value by creating the appropriate conditions for subsequent chemical flooding.