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Carbon 9 (C9) resin is a major by-product of the petrochemical industry and is rich in unsaturated hydrocarbons. By copolymerization with maleic anhydride (MAH), the product MAH-C9 was used as a carbon foaming agent. Combining MAH-C9 with ammonium polyphosphate (APP), which served as an acid and a gas source, an intumescent flame-retardant system was introduced into thermoplastic polyurethane (TPU). Flammability evaluation indicated that 4.5 wt% APP and 0.5 wt% MAH-C9 helped TPU achieve the maximal limiting oxygen index value of 25.9%, passing UL-94 V-0 rating. Total smoke release was decreased from 1,884.4 [m.sup.2]/[m.sup.2] for neat TPU to 833.0 [m.sup.2]/[m.sup.2] and char formation was promoted. The mechanical loss brought by 5 wt% APP was a little recovered by 4.5 wt% APP/0.5 wt% MAH-C9. POLYM. ENG. SCI., 60:1029-1034, 2020., INTRODUCTION Thermoplastic polyurethane (TPU) has been widely used in many fields such as coatings, adhesives, wires and cable, automobiles, etc. [1-3]. TPU advantages include excellent mechanical properties, chemical resistance, abrasion [...]

HPAM/PEI gel is a promising material for conformance control in hydrocarbon reservoirs. However, its use in low-permeability reservoirs is limited by the high polymer concentrations present. In this study, the gelation performance of an HPAM/PEI system with HPAM < 2.0 wt.% was systematically investigated. The gelation time for HPAM concentrations ranging from 0.4 to 2.0 wt.% varied from less than 1 h to 23 days, with the highest gel strength identified as grade H. The hydrodynamic radius manifested the primary effect of HPAM on the gelation performance. Branched PEI provided superior gelation performance over linear PEI, and the gelation performance was only affected when the molecular weight of the PEI varied significantly. The optimal number ratio of the PEI-provided imine groups and the HPAM-provided carboxylic acid functional groups was approximately 1.6:1~5:1. Regarding the reservoir conditions, the temperature had a crucial effect on the hydrodynamic radius of HPAM. Salts delayed the gelation process, and the order of ionic influence was Ca2+ > Na+ > K+. The pH controlled the crosslinking reaction, primarily due to the protonation degree of PEI and the hydrolysis degree of HPAM, and the most suitable pH was approximately 10.5. Plugging experiments based on a through-type fracture showed that multi-slug plugging could significantly improve the plugging performance of the system, being favorable for its application in fractured low-permeability reservoirs. [ABSTRACT FROM AUTHOR]

Considering the damage caused by conventional fracturing fluid in low-permeability reservoirs, a novel fracturing fluid (FNG) combining hydroxypropyl guar (HPG) and functionally modified nano-silica (FMNS) was prepared. The properties of heat/shear resistance, rheological property, proppant transportation, and formation damage were evaluated with systematic experiments. The results showed that the viscosities of FNG before and after the heat/resistance were 1323 mPa·s and 463 mPa·s, respectively, while that of conventional HPG gel was 350 mPa·s. FNG is a pseudoplastic strong gel with a yield stress of 12.9 Pa, a flow behavior index of 0.54, an elastic modulus of 16.2 Pa, and a viscous modulus of 6.2 Pa. As the proportions of proppant mass in further sections transported with FNG were higher than those transported with HPG gel, FNG could transport the proppant better than HPG gel at high temperatures. Because of the amphiphilic characteristics of FMNS, the surface/interface properties were improved by the FNG filtrate, resulting in a lower oil permeability loss rate of 10 percentage points in the matrix than with the filtrated HPG gel. Due to the considerable residual gel in broken HPG gel, the retained conductivity damaged with broken FNG was 9.5 percentage points higher than that damaged with broken HPG gel. FNG shows good potential for reducing formation damage during fracturing in low-permeability reservoirs in China. [ABSTRACT FROM AUTHOR]