Study On Preparation And Properties Of Covalently Composed Water-swellable Rubber

For the special reservoir environment of high temperature(130?),high salt(2.15×10~5mg/L)and long distance transportation(4000 meters underground)in Tahe oilfield,Xinjiang province,it is urgent to prepare DWSR with excellent mechanical properties and expansion performance,and able to withstand high temperature,high salt and low migration.At present,WSR generally has the problems of poor salt-resistance,poor high-temperature resistance,migration of water absorbent polymer(SAP)and fast expansion,which makes it difficult to meet the practical application demand of Tahe oilfield.To solve the technical bottlenecks,the salt-resistance of cationic polyacrylamide(CPAM)as absorbent polymer,excellent comprehensive properties of hydrogenated nitrile butyronitrile rubber(HNBR)as matrix,4,4'-diphenylmethane diisocyanate(MDI),polyurethane(PU),HEMA@PU and semi-HEMA@PU as covalent grafting modified material,and the blocking performance of organic montmorillonite(OMMT)as water blocking material added into the filler of WSR,the high performance delay expansion WSR which can withstand high temperature,high salt and low migration has been prepared to fill the gap in the industry.In this paper,the reaction compound modification scheme will be described in the following three aspects.1.In order to improve the salt-resistance and migration problem of WSR,the graft products of MDI with polyethylene glycol(PEG)and CPAM were used in this chapter to prepare WSR with high salt-resistance and low migration.The effect of MDI content on the mechanical properties and stability of WSR was studied,and the reaction of MDI with PEG and CPAM was determined by FTIR.WSR was prepared with different rubber matrix materials,and the effects of matrix materials on the mechanical properties and expansion properties of WSR were studied.The results showed that with the increase of MDI,the salt-tolerance,mechanical properties and stability of WSR were significantly improved,which solved the problems of poor salt-resistance and volume shrinkage of WSR after expansion.Among the WSR prepared with different rubber matrix,the HNBR have the best comprehensive properties,which not only have excellent mechanical properties,but also have the highest volume expansion rate in different mineralized medium.2.Based on chemical modification method,the preparation and properties of novel WSR with excellent mechanical properties,high expansion properties,high salt-tolerance and low migration were investigated in this dissertation.Modified resins,such as PU,HEMA@PU and semi-HEMA@PU,built the cross-linked network structure via grafting reactions between PAM and rubber matrix,thus the resultant network improved the mechanical properties,expansion properties and stability of WSR.The results show that the mechanical properties and volume expansion rate of WSR can be improved by increasing the content of PU.When PU content is 40 phr,WSR has the best mechanical properties.When PU content is 80 phr,WSR has the maximum volume expansion ratio.The expansion rate,mechanical properties and stability of WSR can be increased by increasing the content of HEMA@PU.When HEMA@PU was 10 phr,WSR had the best comprehensive performance.With the increase of semi-HEMA@PU content,the volume expansion ratio and stability of WSR increase continuously,while its mechanical properties increase first and then decrease.The comprehensive performance of WSR is best when the semi-HEMA@PU content is 50 PHR.PU-type modified materials not only strengthen the construction of WSR interpenetrating cross-linking network,but also increase the mechanical properties and expansion properties of WSR,leading to the obvious improvement of WSR mechanical properties,expansion ratio,stability and salt-tolerance.3.Aiming at the problem of water plugging in Tahe oil field of northwest Xinjiang,which is characterized by high temperature,high salt and requiring long distance transportation of water plugging material,the CPAM,semi-HEMA@PU and lamellar barrier materials ware introduced to fills of DWSR,and the swelling properties,mechanical properties and stability were studied.Delay expansion rubber(DWSR)with high temperature resistance,high salt-resistance and low migration was prepared,and the expansion property,mechanical property and stability of DWSR were studied.The research results show that adding lamellar barrier material can effectively increase the delay expansion time of DWSR without affecting the expansion rate,and the fills of CPAM and semi-HEMA@PU can increase the mechanical properties,expansion properties and stability of DWSR.The evenly distributed lamellar barrier material can extend the time for water molecules to bind to SAP,thus achieving the delayed expansion effect of WSR.Compared with WSR with no delay time,the delay expansion time of DWSR with OMMT and MP was increased to 52 h and 39 h.The novel WSR exhibited the improved volume expansion ratio,mechanical properties and salt-resistance.The technical problems of expansion volume shrinkage caused by migrationt of SAP and delayed expansion of rubber plugging agent were solved in this dissertation...