Temperature And Salt Resistance Of Polymer Synthesis, Characterization And Performance Evaluation

At present, China's major oil fields have moved into the development with water. The use of tertiary recovery to enhance crude production rate become necessary. Among them, more and more attention is paid to the polyacrylamide polymer represented as oil displacement agent. How to improve the polyacrylamide polymer of temperature and salt resistance properties, enable it to adapt the development of high temperature and high salinity reservoirs which becomes the key point to the large oil researcher work. In this paper, through molecular design, synthesis of three polyacrylamide polymers which have good temperature and salt resistance properties, and the property of its solution have been evaluated.The main research content as follows:(1) through molecular design, choose AM as basic monomer,AMPS as second functional monomer,AES,DMAEMA and long chain sulfonic acid monomer as third functional monomer,use orthogonal experimental design and single element experimental design evolve synthesis experiment. The optimum synthesis conditions have determined: monomer concentration25%, the match of monomerAM:AMPS:the third functional monomer=4:1:0.1, initiator concentration0.012wt%, reaction temperature60℃,reaction time 10 hours,pH 6.8.(2)The percent solids,degree of hydrolysis,intrinsic viscosity and molecular weight of each polymer have been determined. also constitution of each polymer have been characterized by infrared spectrometer,the results show that the polymer indeed have been synthetised by those three monomer.(3)The temperature and salt resistance properties of each polymer have been evaluated at70℃～90℃, the results show that, in different concentration or salinity, the temperature and salt resistance properties of terpolymer are obviously better than the normal HPAM. After 90 days in the drying oven,the viscosity of polymer which without salt did not drop at 70℃, viscosity retentivity is 90% at 80℃, viscosity retentivity is 80% at 90℃.The viscosity retentivity of polymer which with different salinity after 30d not drop.After 60d, not drop at 70℃, viscosity retentivity is 70% at 80℃,also have viscosity at 90℃.(4) Evaluate the gel property of polymer by organic zirconium cross-linking system and organic phenolic cross-linking system. The affection of polymer concentration,crosslinker concentration,temperature and salinity have been researched. The results show that:(a)In organic zirconium cross-linking system when polymer concentration at 5000-6000mg/L,the ratio of polymer concentration and crosslinker concentration at 1:1～10:1,the temperature at 80℃～90℃,the polymer have good gel property. (b)organic phenolic cross-linking system when polymer concentration at 5000-6000mg/L,the ratio of polymer concentration and crosslinker concentration at 1:2.5-1:l,the temperature at 80℃～90℃,the polymer have good gel property.Also.the long term stability of polymer gel have been evaluated in each crosslinker. After 60 days in the 90℃drying oven, the intensity of terpolymer gel system changes little and dehydration or link blanking have not appearance. However, only after 60 days in the 90℃drying oven the normal HPAM appear to have intensity decrease,dehydration and link blanking. Comparative test show that terpolymer gel system have good gel property and long term stability.(5)Use scanning electron microscope to observe polymer gel.The results show that:the polymer gel system have space net structures which range complex and closely,the net connection points connect solidity and compact,the net hole have moderate size, well cross linking reaction have done, showed good net structure of polymer gel.These results show that the polymer system which design and synthesis in this thesis have more excellent heat resistance and salt tolerance in long-time thermal stability, the polymer gel system have suitable gel strength and good long-time stability, can meet the needs of Oil-field exploitation in a certain extent. Therefore, the terpolymer use in EOR flooding as the main oil displacement agent and the blocking agent will have relatively good prospect.