Evaluation of Ultra Low Concentration Surfactant System for Chemical Flooding

In order to select a surfactant formulation for chemical flooding, the surfactant has to be evaluated at reservoir conditions to determine its compatibility with the reservoir to be injected in. This is to avoid formation of gels and precipitation in the reservoir which can make surfactant enhanced oil recovery unsuccessful. In several studies, surfactants have been tested in the laboratory at room temperature using only sodium chloride salt in the brine. While in oilfield scenario, the temperature is higher and the reservoir brine contains divalent ions. In this study, very low concentration alcohol alkoxy sulfate with and without a co-surfactant in hard brine and medium crude oil has been evaluated. The results from the salinity scan, phase behaviour and core flooding experiments at 60°C shows that alcohol alkoxy sulfate is tolerant to divalent ions and its stability can be improved with the addition of methyl ester sulfonate and internal olefin sulfonate as co-surfactants. These co-surfactants were able to reduce the viscosity of microemulsion phase, create a lower interfacial tension by increasing solubilisation ratio and also increase oil recovery by at least 20%

Systematic comparative study of Polyacrylamide Co-polymers for EOR at High Salinity Conditions

Polymer flooding is the more successfully and mature chemical EOR technique (Manrique, 2007), The success of polymer flooding as a method of oil recovery has been attributed to a profile control mechanism between polymer solution and oil during water flooding. Two important parameters are important on this process: Mobility Ratio (M) and Capillary Number (Nc) (Thomas, 2007, Karpan, 2011). As polymers are injected in the reservoir, they are exposed to chemical, physical and mechanical degradation that affect their performance in sweeping the crude oil trapped in the porous medium. The effect is critical under high salinity brine with divalent ions Ca2+ and Mg2+. The object of this research was to study the effect of flow behaviour of HPAM (hydrolysed poly-acrylamide) of different molecular weight (MW) and special co-polymers PAM as chemical flooding of sandstones core rocks under high salinity conditions, and under harsh conditions of brine composition existing in the North Sea

Comparative Study of Polyacrylamide Co-polymers for EOR at High Salinity Conditions “Laboratory and Simulation"

Summary: The success of polymer flooding as a method of oil recovery has been attributed to a profile control mechanism of the displacing fluid (polymer solutions) related to the displaced fluid (crude oil), depending on properties such as polymer viscosity and its dependence with reservoir and flow conditions. The viscosity of polymer flow depends not only on the size of the molecules or molecular weight but it is further affected by salinity and divalent content on the brine used for the preparation of the polymer slug. The effect of salinity on polymer viscosity is more critical in presence of divalent ions Ca2+ and Mg2+ and high salinity conditions, which limits the use high salinity produced water for re-injection in polymer flooding processes where high salinity is involved. A series of salinity resistant polymers have been developed by incorporating co-monomers including hydrophilic and hydrophobic groups or combination of them along the chain of polyacrylamide which has made the viscosity behavior more complex and affected by ionic interactions both intra-molecular and inter-molecular. Therefore, an extensively screening process that includes evaluation of variables such as: stability of polymer solutions under salinity and ion composition, flow conditions and sensitivity analysis using simulation according to specific applications, is required for the selection of any specific system. A systematic comparative study of the screening of commercial partial hydrolysed polyacrylamide (PHPA), and co-polymers of acrylamide and hydrophobic modified Comb-polymers (HMPAM) under high salinity conditions is investigated. Synthetic high salinity and multi-component (with divalent ions) produced water from a North Sea reservoir was used on Bernheimer sandstone core samples using a crude oil from the North Sea with specific gravity 21 ºAPI. Results from core flooding and rheology were matched to obtain required mathematical correlations to simulate core flooding experiments numerically and compare the efficiency of the different polymers. While polymers PHPA and co-polymers AM-AMPS and AM-nVP showed typical Newtonian behavior at low shear rates and non- Newtonian at high shear rates, HMPAM polymers have shear thinning behavior. Newtonian behavior on PHPA-3 seems to support its higher recovery factor comparing with PHPA-6 (higher MW). Viscosity of HMPAM solutions is more sensitive to changes of the polymer concentration and more sensible to flow conditions. Additionally, ionic interactions and steric effects in the co-polymers contribute the efficiency of the oil recovery at high salinity. Therefore, their viscosity behavior needs to be evaluated

Invariance of the trait emotional intelligence construct across populations and sociodemographic variables

Cultural, linguistic and sociodemographic peculiarities may influence trait Emotional Intelligence (trait EI). An instrument capable of assessing trait EI in different populations can foster cross-cultural research and make an important contribution to the construct's nomological network. Accordingly, the present study aimed to examine the relationship between trait EI and key sociodemographic variables through univariate analyses of variance and tests of multigroup measurement equivalence. We used datasets Trait Emotional Intelligence Questionnaire (TEIQue-SF) datasets from four countries. Collectively, these datasets comprised 2228 participants, 23% from Brazil, 15% from Chile, 23% from Italy, and 39% from the United Kingdom. The sociodemographic variables that we used for trait EI comparisons were gender, age, educational level, civil and occupational status. Our results indicated significant global trait EI differences across countries for civil status, occupation, educational attainment, and age. Measurement invariance across the datasets was acceptable, especially for age, gender and education. In conclusion, the present psychometric evidence supports the suitability of the TEIQue-SF for the accurate assessment of trait EI in transcultural research

Outcomes following autologous hematopoietic stem cell transplant for patients with relapsed Wilms' tumor: a CIBMTR retrospective analysis.

Despite the marked improvement in the overall survival (OS) for patients diagnosed with Wilms' tumor (WT), the outcomes for those who experience relapse have remained disappointing. We describe the outcomes of 253 patients with relapsed WT who received high-dose chemotherapy (HDT) followed by autologous hematopoietic stem cell transplant (HCT) between 1990 and 2013, and were reported to the Center for International Blood and Marrow Transplantation Research. The 5-year estimates for event-free survival (EFS) and OS were 36% (95% confidence interval (CI); 29-43%) and 45% (95 CI; 38-51%), respectively. Relapse of primary disease was the cause of death in 81% of the population. EFS, OS, relapse and transplant-related mortality showed no significant differences when broken down by disease status at transplant, time from diagnosis to transplant, year of transplant or conditioning regimen. Our data suggest that HDT followed by autologous HCT for relapsed WT is well tolerated and outcomes are similar to those reported in the literature. As attempts to conduct a randomized trial comparing maintenance chemotherapy with consolidation versus HDT followed by stem cell transplant have failed, one should balance the potential benefits with the yet unknown long-term risks. As disease recurrence continues to be the most common cause of death, future research should focus on the development of consolidation therapies for those patients achieving complete response to therapy

Artificial light pollution influences behavioral and physiological traits in a keystone predator species, Concholepas concholepas

Artificial Light At Night (ALAN) is an increasing global problem that, despite being widely recognized in terrestrial systems, has been studied much less in marine habitats. In this study we investigated the effect of ALAN on behavioral and physiological traits of Concholepas concholepas, an important keystone species of the south-eastern Pacific coast. We used juveniles collected in intertidal habitats that had not previously been exposed to ALAN. In the laboratory we exposed them to two treatments: darkness and white LED (Lighting Emitting Diodes) to test for the impacts of ALAN on prey-searching behavior, self-righting time and metabolism. In the field, the distribution of juveniles was observed during daylight-hours to determine whether C. concholepas preferred shaded or illuminated microhabitats. Moreover, we compared the abundance of juveniles collected during day- and night-time hours. The laboratory experiments demonstrated that juveniles of C. concholepas seek out and choose their prey more efficiently in darkened areas. White LED illuminated conditions increased righting times and metabolism. Field surveys indicated that, during daylight hours, juveniles were more abundant in shaded micro-habitats than in illuminated ones. However, during darkness hours, individuals were not seen to aggregate in any particular microhabitats. We conclude that the exposure to ALAN might disrupt important behavioral and physiological traits of small juveniles in this species which, as a mechanism to avoid visual predators, are mainly active at night. It follows that ALAN in coastal areas might modify the entire community structure of intertidal habitats by altering the behavior of this keystone species

Application of Low Concentration Surfactant Enhanced Water-Alternating-Gas Flooding

Large amounts of oil left in the petroleum reservoir after primary and secondary enhanced oil recovery methods have brought about the implementation of several tertiary means of oil recovery. Increment of oil recovery can support the world’s oil supply. Water alternating gas injection has been a very popular method of gas injection to improving volumetric sweep efficiency. Although water alternating as injection has been shown to improve oil recovery, this process suffers inherent challenges such as water blocking, mobility control in high viscosity oil and gravity segregation. To combat these problems associated with water alternating gas flooding, the use of surfactant has been employed in water alternating gas injection. Due to the high operational cost arising from chemical cost in surfactant alternating gas injection, a new technique which involves the injection of low concentration surfactant before water alternating as flooding has been proposed. This work investigates experimental and numerical oil recovery potential of surfactant enhanced water alternating gas flooding. The distinctive feature of this technique is that instead of injecting surfactant slugs alternatively with gas, which will result to using a greater amount of surfactant, a low concentration surfactant is injected into the reservoir before water alternating gas flooding. The aim is to evaluate the performance of this technique as a low cost and effective means of chemically enhanced oil recovery by combining both mechanisms of surfactant reduction of water-oil interfacial tension and creation of foam with gas. This study begins with surfactant evaluation to characterise surfactants compatibility with reservoir brine and oil. Then followed by series core flooding experiments which include waterflooding, gas flooding, water alternating gas flooding and surfactant-enhanced water alternating gas flooding. Core flood data was history matched for water alternating as flooding and surfactant-enhanced water alternating as flooding via commercial simulator by inputting relative permeability curves, rock, fluid properties and interfacial tension. The results showed that experimentally, surfactant enhanced water alternating as flooding had the highest oil recovery when compared to conventional enhanced oil recovery methods. History matching of core flood experiment predicted similar increment in oil recovery during surfactant enhanced WAG. The effectiveness of this technique is based on the injection pattern after the initial surfactant injection and oil recovery potential is similar to that of surfactant alternating gas flooding

Gad65 is recognized by t-cells, but not by antibodies from nod-mice

Since the 64kDa-protein glutamic acid decarboxylase (GAD) is one of the major autoantigens in T-cell mediated Type 1 diabetes, its relevance as a T-cell antigen needs to be clarified. After isolation of splenic T-cells from non-obese diabetic (NOD) mice, a useful model for human Type 1 diabetes, we found that these T-cells proliferate spontaneously when incubated with human GAD65, but only marginally after incubation with GAD67, both recombinated in the baculovirus system. No effect was observed with non-diabetic NOD mice or with T-cells from H-2 identical NON-NOD-H-2g7 control mice. It has been published previously that NOD mice develop autoantibodies against a 64kDa protein detected with mouse beta cells. In immunoprecipitation experiments with sera from the same NOD mice and 33S-methionine-labelled GAD, no autoantibody binding could be detected. We conclude firstly that GAD65 is an important T-cell antigen which is relevant early in the development of Type 1 diabetes and secondly that there is an antigenic epitope in the human GAD65 molecule recognized by NOD T-cells, but not by NOD autoantibodies precipitating conformational epitopes. Our results therefore provide further evidence that GAD65 is a T-cell antigen in NOD mice, being possibly also involved in very early processes leading to the development of human Type 1 diabetes

May Measurement Month 2017: analysis of the blood pressure screening results in Argentina-Americas

Hypertension is a growing concern worldwide, causing over 10 million deaths each year. The prevalence of high blood pressure (BP) in Argentina is 36.3% and 38% of these are unaware of their disease. Half of the hypertensive patients are on pharmacological treatment and only a quarter of them are controlled. The International Society of Hypertension initiated the May Measurement Month (MMM) as a global campaign to raise awareness on high BP that may also serve as a temporary solution to the lack of global screening programs worldwide. A volunteer cross-sectional survey was carried out in May 2017 across 56 health centres. Blood pressure measurement, definition of hypertension and statistical analysis followed the MMM protocol. For this awareness campaign, the Argentine Society of Hypertension coined the slogan: 'Know and control your blood pressure'. A total of 32 346 individuals aged at least 18 years were screened during MMM17. After imputation, 16 263 (50.4%) were hypertensive. Of the 12 156 receiving antihypertensive medication 5400 (44.4%) still had uncontrolled BP. MMM17, called in our country 'Know and control your blood pressure', was the largest BP screening campaign done in Argentina. Almost 6 out of 10 hypertensive patients were either not on treatment or were not controlled to the BP goal. These results suggest that appropriate screening can help to identify a significant number of people with high BP