Polymer flooding is one of the most attractive chemical EOR techniques for sandstone reservoirs however due to complex geological heterogeneity and harsh reservoir conditions its full potential has not been explored in carbonate reservoirs. The main reason behind this limitation is the inability of conventional EOR polymers like HPAM and Xanthan to withstand these conditions. Candidate polymers must provide the required rheology at minimal polymer concentration, be thermally and mechanically stable, and result in a manageable adsorption on the reservoir formation. A polymer screening study has been conducted on a series of polymers, to identify the most suitable candidate that can tolerate the harsh reservoir conditions. Initially, rheological measurements are conducted on a series of polymers followed by filterability, injectivity, static and dynamic adsorption, mechanical and thermal stability testing as a screening criterion for polymers in EOR operations. Amongst the tested polymers polyacrylamide based co- and ter-polymers showed reasonable temperature stability with low salinity tolerance. Whereas, biopolymer Schizophyllan a polysaccharide showed shear thinning behavior with positive thermal stability and salt tolerance. Long-term thermal stability of biopolymer is also conducted at a temperature of 120 °C and salinity up to 220 g/L under anaerobic conditions for over eight months and no viscosity loss is observed. Biopolymer showed acceptable injectivity on cores of permeability more than 30 mD. Core flood effluents viscosity reached 40% compared to injected sample. In addition the mechanical stability and filterability of biopolymer are also discussed. Static as well as dynamic adsorptions of biopolymer have also been studied. The static adsorption on four natural minerals (Calcite, Dolomite, Kaolin, and Silica) as well as formation rocks is reported. Out of these four minerals, maximum and minimum adsorption is observed on Dolomite and Kaolin respectively. The adsorption of biopolymer decreases with salinity and temperature. Adsorption on carbonate reservoir rocks is found to be low when compared to pure calcite and dolomite minerals. Dynamic adsorption on cores with different permeabilites (3 to 165 mD) is measured to be low in magnitude (47.5 to 0.53 µg/g).

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BackgroundSesquiterpene lactones (STLs) make a diverse and huge group of bio-active constituents that have been isolated from several plant families. However, the greatest numbers are present in Asteraceae family having more than 3000 different reported structures. Recently several researchers have reported that STLs have significant antioxidant and anticancer potentials.MethodsTo investigate the antioxidant, anticancer and antinociceptive potentials of STLs, gravity column chromatography technique was used for isolation from the biologically rich chloroform fraction of Artemisia macrocephala Jacquem. The antioxidant activity of the isolated STLs was determined by DPPH and ABTS free radical scavenging activity, anticancer activity was determined on 3 T3, HeLa and MCF-7 cells by MTT assay while the antinociceptive activity was determined through acetic acid induced writhings, tail immersion method and formalin induced nociception method.ResultsThe results showed that the STLs of Artemisia macrocephala possesses promising antioxidant activity and also it decreased the viability of 3 T3, HeLa and MCF-7 cells and mild to moderate antinociceptive activity.ConclusionSesquiterpenes lactones (STLs) are widely present in numerous genera of the family Asteraceae (compositae). They are described as the active constituents used in traditional medicine for the treatment of various diseases. The present study reveals the significant potentials of STL and may be used as an alternative for the management of cancer. Anyhow, the isolated compound is having no prominent antinociceptive potentials.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1517-y) contains supplementary material, which is available to authorized users.

The study has shown that the creatinine-based niosomes developed in our laboratory were biocompatible, safe and increased the oral bioavailability of the model hydrophobic Clarithromycin using experimental animals.

A three component catalyst system entailing an amino acid (O(t)Bu-L-threonine), a hydrogen bond donor (sulfamide), and an amine base (DMAP) allows α-branched aldehyde addition to nitroalkenes in good to high yield and excellent ee. Importantly, the lowest reported catalyst loading (5.0 mol%) and aldehyde stoichiometry (1.2-2.0 equiv) is demonstrated and in most instances the best current product profile is observed.