Study Of New-style Fluid Diverting Agent

Aiming at the characters of hydrogel particles using in oilfields at present, we have developed a new kind of polymer gel by means of IPN. The application performance of the newfashioned gel is delved into.(1) After designing the molecular structure, the composite principle, the synthetic route and the synthetic conditions are studied. It can meet the demands of application performance with PVA, PAM and PAA for basic molecular constitution. PVA, PAM and PAA have good compatibility at the same time. Order IPN is the optimal synthetic route. PVA concentration has most impact on strength, swelling capacity and dehydra -tion rate of the gel. The mutual effect of PVA concentration and second cross-linking agent dosage has most impact on over-all properties.(2) The structure was attributed by the means of infrared spectrum, polarizing microscope, transmission electron microscopy, and Differential Scanning calorimetry. Intermolecular hydrogen bonding forms between PVA, PAM and PAA. IPN gel shows network structure and the aggregate of the network structures is spherical particle, the crystal structure can also be observed obviously. The water-absorbed gel shows cones -cutive membrane strap (10～30μm) and separate anomalous sub-elliptical structure (25～50μm). Along with the conet of P(AM-AA) rising, the crystal structure of IPN gel goes to ruin gradually.P (AM-AA) cellular size has also effect on the crystal structure.(3) The strength, the downiness and the toughness of IPN hydrogel are evaluated roundly using mechanics tensile tests. The more PVA concentration is, the higher gel strength is. The more moner dosage is, the worse gel downiness is. The gel has best toughness at the conditions that PVA concentration 2%, moner dosage 20%, initiator dosage 0.12%, first cross linker dosage 0.04% and second cross linker dosage 0.05%.(4) The swelling kinetics of hydrogel and the state of the water in hydrogel is studied; the swelling behaviors of IPN gel in buffer solution at various pH and in deionized water at different temperature and in different saline solution are analyzed. Swelling of IPN gel belongs to not-fickian course. Water inside the gel has three states. The content of free water is above 55% and that of non-frozen hydration water less than 5%. The content of free water dominates the gel swellablity. IPN gel shows different swelling behavior at different environment solution.(5) The dehydration model is deducted; the dehydration dynamics of IPN gel in air ambience is researched; the dehydration performance of the IPN hydrogel in forma -tion water and oil are investigated. The dehydration rate reduces along with the incre -asement of crosslinking density when crosslinking density is less than the critical density. The pressure effect on gel by crude oil is the main cause of dehydration in crude oil. There is no dehydration when IPN gel is soaked into formation water(120℃, 150000mg/L) for 3 months. So IPN gel has excellent stability.