Preparation and performance evaluation of the slickwater using novel polymeric drag reducing agent with high temperature and shear resistance ability

Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.

Characterization on Surface and Interfacial Properties of Nitramine Crystal Fillers and Polymeric Bonding Agents

The surface and interfacial properties of polymeric bonding agents and nitramine crystal fillers were studied. The surface free energy and adhesion work of polymeric bonding agents and nitramine fillers were calculated by using Kaeble′s equations. It was observed that the hydroxyl values of neutral polymeric bonding agents (NPBA) correlate well with the polar components of surface free energies. On the basis of the measurements of swelling ratio and initial modulus, the interfacial bonding through highly crosslinked polymeric shell formation around the nitramine particles and generating interfacial reinforcement were rationalized. The application of Tapping Mode AFM (atomic force micro scope) to observing the surface morphology of NPBA reveals that methyl acrylate monomer appears to play a role for aiding the formation of network like structure when nanometer scale images of NPBA are created.

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

Fluxing Agents on Ceramification of Composites of MgO-Al2O3-SiO2/Boron Phenolic Resin

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al_2O_3-SiO_2/boron phenol formaldehyde resin（MAS/BPF） composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS/BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS/BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS/BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.

THE TRANSITION METAL COMPOUNDS CATALYZED BOROHYDRIDE EXCHANGE RESIN TO REDUCE THE AROMATIC NITRO COMPOUNDS

Aromatic nitro compounds are reduced to correspouding amiues in ethanol by borohydride exchauge resin(BER)in the presence of transition metal Pd,Co,Ni,Cu)compounds as catalysts.

Synthesis and biological evaluation of 5,6,7-trimethoxy-1-benzylidene-3,4-dihydro-naphthalen-2-one as tubulin-polymerization inhibitors

A series of new combretastatin-A4 analogs were synthesized, in which a six-membered ring connects the linking bridge and A ring, and their tumor cell growth and tubulin-polymerization inhibitory activity were evaluated. These compounds appear to be potential tubulin-polymerization inhibitors, Compounds 1b with amino substituted on position 3 of B ring conferred optimal bioactivity, higher than that of the lead compound 22b and equivalent to that of CA-4. The binding modes of these compounds to tuhulin were obtained by molecular docking, which can explain the structure-activity relationship. The studies presented here provide a new structural type for the development of novel antitumor agents.

Rheology of diluted and semi-diluted partially hydrolyzed polyacrylamide solutions under shear:Experimental studies

Rheological properties of hydrolyzed polyacrylamide(HPAM)solutions were measured in oscillatory and flow shear.In oscillatory shear the storage and loss moduli increased as the concentrations of the solutions increased,but they decreased as salinity increased.The relaxation spectra were plotted using the Kontogiorgos method.As shown in the relaxation spectra,the number of density of segmental units increased at first and then the peaks shifted and split into several as the concentration increased.With salinity increasing,the number of motion units increase and the peaks of segmental units became broader.In flow shear tests,the curves of viscosity versus shear rate were fitted by a power law equation.The result showed that the flow behavior index decreased with increasing concentration,while it generally increased with increasing of salinity.Furthermore,the first normal stress difference increased as the concentration was increased,while it decreased as the salinity was increased.The first normal stress differences measured by the rheometer were compared with the first normal stress differences calculated by the Laun equation and the results showed that Laun equation deviates the experimental results.