Study On The Preparation And Application Of Inorganic Organic Composite Profile Control Agent

In this research, both one type of organic-inorganic composited hydrogel based on the acrylamide (AM), calcium bentonite and sodium silicate and the other based on the 2-acrylamide-2-methylpropane sulfonic acid (AMPS), acrylamide (AM) and calcium bentonite as profile control agent were prepared with free radical solution polymerization using ammonium persulfate/sodium bisulfate as a redox initiating pairs, and N,N’ -methylene-bis-acrylamide (MBA) or ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The first one was called PAM/calcium bentonite/sodium silicate hydrogel, and the other was P(AM-AMPS)/calcium bentonite hydrogel. The composited hydrogels were both characterized by fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and thermogravimetry (TG) analysis. Effects of calcium bentonite content, sodium silicate content (or monomer ratio of AM to AMPS), initiator dosage, and polymerization temperature and cross-linker type and dosage on the swelling capacity, water absorption rate and compressive strength of the two profile control agents were investigated by a series of experiments. Meanwhile, effects of calcium bentonite content, sodium silicate content (or monomer ratio of AM to AMPS) and cross-linker dosage of MBA on the heat resistance were investigated, too. The optimum processing technology of the two profile control agents was obtained, respectively.The results indicated that the stable network structure was formed between silicon-oxygen long-chains and PAM chains, and the calcium bentonite particles were dispersed in the hydrogel. The swelling capacity of the PAM/calcium bentonite/sodium silicate hydrogel was lower than that of PAM hydrogel. Compared to the PAM hydrogel, the cost for PAM/calcium bentonite/sodium silicate (the calcium bentonite addition percentage was 100%) was reduced by 51%, the compressive strength was enhanced about 5 times, and the heat resistance time was increased by 67%. In a word, the PAM/calcium bentonite/sodium silicate hydrogel prepared in this work possessed a lower cost and a higher performance than that of the PAM hydrogel. The novel hydrogel has potential profile control applications for enhanced oil recovery (EOR) in oilfield. The optimum processing condition was determined as follows:the AM was 20 g, the cross-linker MBA dose was 0.8%, the percentage of initiator was 0.02%, sodium silicate dose was 8%, calcium bentonite percentage was 100%, and the reaction temperature was 60℃.For the P(AM-AMPS)/calcium bentonite hydrogel the optimum processing technology was as follows:the mass ratio of AM to AMPS was 9:1, MBA dose was 0.08 wt%, initiator dose was 0.1 wt%, calcium bentonite percentage was 100% and the reaction temperature was 60℃. The results indicated that monomers AMPS and AM had polymerized and formed stable network structure, and the calcium bentonite particles dispersed in the hydrogel. The swelling capacity of P(AM-AMPS)/calcium bentonite hydrogel decreased with the increase of the addition of the calcium bentonite. Compared to P(AM-AMPS) (calcium bentonite addition percentage zero), the cost for P(AM-AMPS)/calcium bentonite (calcium bentonite addition percentage 100%) was reduced by 50%, the compressive strength was enhanced to 6 times, the heat resistance time was increased to 2.5 times, and the thermal stability was increased by 34.71%. In a word, the P(AM-AMPS)/calcium bentonite hydrogel prepared in this work possessed the quality of lower cost and higher performance than that of the P(AM-AMPS) hydrogel.