در این تحقیق هیدروژل‌های پایه پلی‌اکریل‌آمید بر اساس روش حلال ساخته شد و خواص رئولوژیکی و کارایی آنها در شرایط فیزیکی چاه‌های نفت جنوب ایران به طور کیفی و کمی به وسیله تست بطری و رئومتر سنجیده شد. بر اساس نتایج به دست آمده از تست بطری، ژل پلیمر محتوی ppm 15000 پلی‌اکریل آمید و ppm 2500 استات کروم (III) که به مدت hr 24 در دمای C° 90 قرار گرفته است، به عنوان ژل پلیمر پایه انتخاب شد. نتایج حاصل از تست‌های رئومتری در دمای C° 25 نشان می‌دهد که مدول کشسان در محدوده فرکانس 1/0 تا Hz 10 و در محدوده کرنش کوچکتر از 100% تقریبا ثابت باقی می‌ماند. در حالی که مدول مذکور از Pa 8 در دمای C° 25 تا Pa 4 در دمای C° 90 افت می‌کند. بررسی تنش تسلیم اعمال شده بر روی ژل پلیمر نشان می‌دهد که در نمونه مذکور سه نقطه کرنش 100%، 3280% و 6470% می‌توانند به نوعی نقطه تسلیم در نظر گرفته شوند و به دلیل اثر سرخوردگی در دیواره، نمی‌توان نقطه تسلیم را به قطعیت پیدا کرد. برای سیستم ژل پلیمر مذکور تا کرنش 6470%، خواص کشسان بر خواص گرانرو غالب است. پس از عبور از این نقطه شبکه به حالت روان درآمد و سیستم دچار پارگی شد.
Investigation of Rheological Properties and Performance of Polymeric Gel Systems (Based on Polyacrylamide) in High Temperature Reservoirs
چکیده [English]
In this research, polyacrylamide based hydrogels were made on the basis of solvent method, and their rheological properties and performance were evaluated by bottle testing and a rheometer under Iran south oil reservoir conditions. Based on the results of the bottle test, the polymeric gel formed by 15000 ppm polyacrylamide and 2500 ppm chromium (III) acetate and kept at 90 °C for 24 hrs was selected as a basic polymeric gel. Based on the results of rheometric tests at temperature of 25°C, the elastic modulus almost remains constant in frequency range of 0.1 to 10Hz and the strain range up to 100%, whereas this module decreases from 8 Pa at 25 °C to 4 Pa at 90 °C. Studying the effect of the applied yield stress on the polymeric gel indicates that for a sample each of three strain points of 100%, 3280%, and 6470% could be considered as a yield point, but it could not be found decisively because of wall slip effect around the rheometer wall. Also, the polymeric gel system does not tear up to the strain of 6470% and the elastic properties are superior to the viscous nature of the system below this point.
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