Oil And Gas Open Hydrophobically Associating Polymer

Enhanced oil recovery (called tertiary oil recovery in the past) processes have as their objective the increase of recovery from reservoirs depleted by conventional recovery, i.e. by primary recovery with natural production mechanisms or by secondary recovery with water-flooding or gas injection. Enhanced oil recovery techniques can be subdivided into three categories: thermal, miscible and chemical. In our country, chemical process is the main technique to enhance oil recovery. Up to now, polymer flooding has succeeded in many oil fields, but both the effectiveness and efficiency of oil recovery need further promoting. Because the most application polymers, such as partially hydrolyzed polyacrylamide and xanthan gum, have met some problems when used in high temperature or high salinity reservoirs. So the developments of new class of polymers, which have the ability of both temperature endurance and salt resistance, become very urgent. Hydrophobically associating water-soluble polymers (HAWSP) for which exhibit special rheological properties different from that of conventional polymers have recently received considerable attention.HAWSP is a kind of water soluble polymer, containing a few hydrophobic groups on the side chains, usually less than 2mol%. Owing to hydrophobic effect, when polymer dissolved in water, some of hydrophobic groups may associate with each other, form super-molecular aggregates, and even transitional network structure, which induces a substantial increase in solution viscosity. So, to some extent, HAWSP can overcome the deficiency of conventional polymers in sensitivity to temperature, ionic strength and shear. Although HAWSP have been studied for many years and the performance of HAWSP is indeed better than that of conventional polymer, the performances of HAWSP in temperature endurance, salt resistance and stabilities need further improving.In order to get the HAWSP with required performances, it is necessary to know its association mechanism in aqueous solution, influencing factors, etc. The confirmation of association mechanism and solution microstructure of HAWSP will help to know the reason why hydrophobic associating polymer has unusual rheological behavior and allow us establish the relationships between polymer architecture and macroscopic properties, and so permit the tailoring of the molecule structure for specific application. So the main tasks of this dissertation are: first of all, study the associating mechanism of HAWSP by fluorescence spectrum, ultraviolet spectrum and transmission electron microscope; then, seek for a method to improve the performances of HAWSP in temperature endurance or salts resistance; thirdly, based on the structure characteristic of HAWSP and the results of the experiments, calculate the critical concentration of HAWSP through model design and the establishment of mathematical model, and put forward the partition of solution regimes of HAWSP. Study of association mechanism of HAWSPFluorescence spectrum and ultraviolet spectrum using pyrene as probe were used to investigate the associating status and the course of the formation of network. The associating mechanism of HAWSP in aqueous solution was deduced: in aqueous solution, with the increase of concentration, HAWSP molecule will associate with each other; then intermolecular associating of HAWSP leads to formation super-molecular aggregates; in the end, a space network structure forms. It was verified by Rheometer that the viscosity of HAWSP solution increased sharply at the concentration when a space network had formed in solution.The microstructures of PAM and HAWSP were investigated by TEM. But both PAM and HAWSP can form network in dilute solution, and it is hardly to distinguish the differences between PAM and HAWSP from the TEM picturesTo make a further understand of the relationship between solution properties and structures, phase separation model was used to investigate the association energy of HAWSP in aqueous solution. Results showed that hydrophobic association energy was smaller than the...