| In the world, heavy oil resources are extremely rich; their exploitation plays an important role in petroleum industry. But most heavy oil resources are distributed in loose sandstones. The physical property itself decides that heavy-oil resources must be exploited by enhanced oil recovery technique; but at present, only the thermal recovery method (mainly refers to steam stimulation and steam flooding) has been used. In the thermal recovery process, loose sandstone reservoir characteristics, steam property and its washing cause sand production, steam fingering/channeling and so on, which influence the exploitation effect. Due to these problems, based on sand control /sealing of compound preflush solidification, combined with the reversible temperature-sensitive thickening characteristic of gel system, the self-adaptive compound profile-control and oil displacement technology is proposed in this paper.Firstly by using free radical aqueous solution polymerization, ternary copolymer P (A-AM-B) and ionic tetra-copolymer P(A-AM-NaAA-B) are synthesized; and then they are characterized to determine their composition and structure by IR technique and so on. And the ternary/tetra-copolymer have the unique performance of reversible thermal thickening which it can be as polymer flooding at low-temperature and sealing at high-temperature. Temperature sensitive performance study illustrates that, when concentration is above certain value ( mass concentration is 2.0%) and temperature is above low critical solution temperature-LCST, the gel system with 3D net structure is formed; viscosity increases with temperature; the addition of external ion strengthen temperature-sensitivity; these show that the ternary/tetra-copolymer have a good heat and salinity tolerance. But the tackifying effect of P (A-AM-NaAA-B) is better than that of P (A-AM-B); and LCST doesn't exist in dilute solution. At the same time, combined with the technique of DSC, DLS and fluorescence spectrum, by using of osmotic pressure kinetic model, the gel temperature-sensitive mechanism is investigated theoretically.The dynamic and static shear performance of P (A-AM-NaAA-B) gel system is researched by HAAKE rheometer; and the result demonstrates that this gel system has shear-thinning property and it belongs to pseudoplastic fluid. When temperature is in the range of and loss angle decreases from 56.27°to 31.04°, the inferior changes from viscous fluid to viscoelastic fluid; and the mechanical strength is analyzed by improved rubber theoretical model. On the creep study basis, combined with the experiment result, the system's kinetic model is derived. The sealing and oil displacement performance of the temperature-sensitive gel system is evaluated by indoor core flooding test which show that the blocking ratio is above 50% at high temperature and only 9.8% at low temperature; these show that the gel system is temperature self-adaptive. At the temperature of 65℃, the indoor physical simulation test show that the oil recovery can be increased by about 18%. At the same time, the mathematical model of damage degree for non-destination when generally injected, is set up; and the gel damage degree is evaluated at low temperature (30℃). Making use of that the dynamic injection multi-cycle steam pressure reflects the gel blocking property, the result illustrates it still has the blocking ability for the steam after multi-cycle.Considering the problems of heavy oil reservoir sand production and large consumption of synthesized tetra-copolymer, it is proposed that the water soluble phenolic resin and inorganic silicide are compounded at acid condition to work as the sand-control/sealing preflush. The optimum recipe of the preflush is selected by orthogonal test; and its stability, salt resistance and acid and alkali resistance are observed; the result shows that it is comparatively stable at 330℃and when Ca2+>0.5% or pH>11 it can't be solidified after 90h but can meet the thermal recovery requirement. In order to guarantee that it has a certain permeability when preflush is solidified, pore-agent is added into preflush; when added more than 40%, the permeability is above 1.17×10-3μm 2. The core flooding test show that preflush with pore-agent after solidification has a high blocking ratio (>95%) and breakthrough pressure gradient (>9.3Mpa/m), but its selective injection is bad-when permeability range is 17.64, the profile improvement ratio is only 87.9%. The sand-control effect of the preflush is studied by dynamic and static tests; and its mechanism of temperature-resistance and sand-control is analyzed from the aspect of bond energy and interaction between nano-paticles.Finally, the compound profile-control and oil displacement technology of preflush and temperature-sensitive gel is studied by indoor experiments; the profile-control and oil displacement effects in different injection manners are measured by orthogonal tests. And a software is programmed to fit the experiment data; the result show the compound system has a good temperature self-adaptivity; and the profile-control flooding index is predicted; the error (5.10% as the maximum) between experimental value and fitted value is analyzed. The consumption amount of preflush and temperature-sensitive gel can be determined by the fitting relation according to the geological conditions; and the self-adaptive compound profile-control flooding mechanism of the temperature-sensitive gel is investigated microscopically. Due to the gel temperature-sensitivity, the multi-field coupling kinetic model is set up, considering the influence of temperature field for fluid seepage; the steam channeling volume is derived from the theoretical analysis; the principle of optimizing profile-control flooding parameters is analyzed; these provide theoretical basis for field treatment.
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