A General Model for the Ideal Chain Length Distributions of Polymers Made with Reversible Deactivation

Polymer molecular weight, or chain length distributions, are a core characteristic of a polymer system, with the distribution being intimately tied to the properties and performance of the polymer material....

Research on Performance Evaluation of PPG/Polymer Flooding System

Aiming at the PPG/polymer flooding system developed by Daqing Exploration and Development Research Institute, this paper conducts research on its viscosity increasing, viscosity stability, rheological properties, viscoelasticity and seepage ability. The experimental results show that:PPG has a thickening effect on the system, and the thickening range is between 37% and 66%;the viscosity retention rate of the PPG/polymer system is higher (88%) than the ordinary 25 million polymer solution (75%) ); Under the same shear rate conditions, the apparent viscosity of the PPG/polymer system is higher than 25 million pure polymer; the PPG/polymer system has a resilience effect, and its G’ and G” values are greater than that of a pure polymer solution;PPG/The polymer system can migrate to the deep part of the oil layer and still maintain high seepage resistance, which can realize deep profile control.

Adsorption of anionic surfactant on surface of reservoir minerals in alkaline-surfactant-polymer system

Alkaline-surfactant-polymer (ASP) flooding is significant to the oil and gas industry due to synergistic interaction between alkaline, surfactant and polymer. However, chemical losses due to adsorptions of surfactant and polymer on the rock surface could lead to inefficiency of the process. There are also significant uncertainties on adsorption mechanism when surfactant is flooded with presence of alkaline and polymer. This study highlights the static adsorption tests using anionic sodium dodecyl sulphate (SDS), hydrolysed polyacrylamide (HPAM) and sodium carbonate (Na2CO3) as the surfactant, polymer and alkaline, respectively. Sand particles and kaolinite clay were used as the reservoir minerals. The adsorption tests were conducted at various surfactant concentrations ranging from 50 to 2000 ppm. Sodium chloride (NaCl) concentration was investigated from 0 to 2 wt.%, while the local sand and kaolinite was mixed in surfactant solution at a fixed mass to volume ratio of 1:5. The static adsorption test was conducted by shaking the mixture samples and centrifugation before analysing the supernatant liquid using UV-Visible spectrophotometer. The results showed that the surfactant adsorption was higher on kaolinite compared to sand particle. The higher the salinity, the higher the adsorption of surfactant due to higher ionic strength. The adsorption of SDS surfactant on sand particles and kaolinite was lesser in ASP system compared to the presence of surfactant solution alone. Thus, it can be concluded that the presence of polymer and alkaline in ASP solution have great potential to reduce the surfactant adsorption on both sand particle and kaolinite.

Immunohistochemical Study of Trophoblasts Cellular Regulation Processes in Chorioamnionitis and Basal Deciduitis Combined with Iron-Deficiency Anemia in Gravidas

The purpose of the study is to establish quantitative parameters of cell proliferation and apoptosis in the trophoblast of the chorionic villi in chorioamnionitis and basal deciduitis combined with iron-deficiency anemia in gravidas by means of immunohistochemical method. Materials and methods. 198 placentas were examined. The immunohistochemical procedure was performed using primary antibodies against Ki-67 and Bax antigen with imaging by a polymer system with diaminobenzidine dye. The number of Ki-67-positive nuclei of the chorionic villi trophoblast was counted, and for the Bax antigen, the optical density of the immunohistochemical staining was measured by means of microdensitometric method. Comparison of differences in mean trends was performed using the odd Student’s two-sided t-test (p≤0.05). Results and discussion. The number of Ki-67-positive trophoblast nuclei in acute chorioamnionitis with iron-deficiency anemia in gravidas was 56±3.8 ‰, and the relative units of optical density of immunohistochemical staining for protein Bax – 0.234±0.0012, in chronic – 59±3.6 ‰ and 0.2, respectively. The number of Ki-67-positive nuclei of the chorionic villi trophoblast was counted. Placentas with acute as well as chronic chorioamnionitis and basal deciduitis showed even higher averages (p <0.001). In acute basal deciduitis in anemia, the number of Ki-67-positive trophoblast nuclei was 56±3.2 ‰, the average optical density of immunohistochemical staining for protein Bax – 0.236±0.0016, in chronic – 57±3.7 and 0.249±0.0015, respectively. It should be noted that in chronic chorioamnionitis and basal deciduitis, these rates were higher than in acute. With the same regularity the average indicators of optical density of immunohistochemical staining on protein Bax in a trophoblast of chorionic villi at comorbid iron-deficiency anemia concerning an inflammation without anemia increase. We have shown that proliferative activity in iron-deficiency anemia varies with gestational age and placental prematurity, but iron-deficiency anemia in gravidas and chorionic tree maturation both individually and in combination lead to the intensification of these processes. We obtained a justification for the arithmetic mean thickness and volume of the placenta relative to observations of placenta with inflammation without anemia in this comorbid pathology. Conclusion. Iron-deficiency anemia in gravidas leads to the intensification of proliferative processes and Bax-dependent apoptosis in the trophoblast of the chorionic villi of the placenta relative to the placenta from physiological pregnancy. In acute as well as in chronic chorioamnionitis and basal deciduitis, the proliferative activity and apoptotic processes in the trophoblast of the chorionic villi of the placenta increase, while comorbid iron-deficiency anemia in gravidas intensifies only the processes of Bax-dependent apoptosis

Study on Formulation with Lower Initial Viscosity Gel/Alkali/Surfactant/Polymer After Polymer Flooding and Scenario Design of Field Test

The blocks of polymer flooding have gradually entered into the stage of chase water flooding after polymer flooding in Daqing Oilfield and the comprehensive water cut is close to the exploitation limit of 98%. So it is urgent to develop some new technologies to further enhance oil recovery after polymer flooding. On the basis of laboratory research, a field test of alkali/surfactant/polymer flooding was carried out after polymer flooding in Daqing Oilfield in 2015, which achieved good development effect, but the polymer concentration was relatively large. Based on the field test of alkali/surfactant/polymer flooding, a new technology of the lower initial viscosity gel/alkali/surfactant/polymer flooding has further been studied according to the technical route combining plugging, adjusting and displacing, which can reduce the polymer dosage greatly under the premise of ensuring good oil displacing effect. In this paper, some laboratory studies are carried out, which realize significant technology breakthrough. Firstly, the adjusting and plugging agent of lower initial viscosity gel is screened out, which can be injected into the high permeability layers of low flow resistance like the water and migrate to the deep location of the high permeability layers and then gelatinize on spot. Therefore it can plug high permeability layers effectively and does not pollute the middle and low permeability layers at the same time. Secondly, the injection parameters of lower initial viscosity gel/alkali/surfactant/polymer system are optimized. The results of laboratory experiments show that the lower initial viscosity gel/alkali/surfactant/polymer system can enhance oil recovery by 13.5% OOIP under the optimal injection parameters, which is 1.2% OOIP more than that of the alkali/surfactant/polymer flooding and can save polymer dosage by 17.8%. In view of the good results obtained in laboratory experiments, the scenario design of field test is carried out and the incremental oil recovery is 10.1% OOIP predicted by numerical simulation. The field test is expected to start chemical flooding in 2021.

Self-assembly of a strapped linear porphyrin oligomer on HOPG

Polymeric structures based on porphyrin units exhibit a range of complex properties, such as nanoscale charge transport and quantum interference effects, and have the potential to act as biomimetic materials for light-harvesting and catalysis. These functionalities are based upon the characteristics of the porphyrin monomers, but are also emergent properties of the extended polymer system. Incorporation of these properties within solid-state devices requires transfer of the polymers to a supporting substrate, and may require a high-degree of lateral order. Here we show that highly ordered self-assembled structures can be formed via a simple solution deposition protocol; for a strapped linear porphyrin oligomer adsorbed on a highly oriented pyrolytic graphite (HOPG) substrate. Two distinct molecule–molecule interactions are observed to drive the formation of two molecular phases (‘Interdigitated’ and ‘Bridge-stabilised’) characterised by scanning tunnelling microscopy, providing information on the unit cell dimensions and self-assembled structure. The concentration dependence of these phases is investigated, and we conclude that the bridge-stabilised phase is a thermodynamically stable structure at room temperature.