| With the rapid development of the world economy, the demand of energy increase dramatically. Oil as the major energy of the society has rapid growth, supply and demand are contradiction. The abundant of heavy oil resources will be the best complement of crude oil. Heavy oil is expected to become an important part in the future of oil exploration in the21st century. Due to large amounts of paraffin wax, resin and asphaltene in the crude, it has the features of high viscosity and high solidifying point and poor fluidity, the production and transportation are difficult. In this reason, the way to solve the problem of exploitable, transportation and refining of heavy oil are reducing viscosity and improving fluidity. Comprehensive analysis of the existing viscosity reduction method, oil-based viscosity reducer for its small dosage, simple treatment, not affect the quality of oil and many other advantages, so the industry generally considered it as the most promising technologies.Daqing heavy oil was chosen for the study. First applied cross-linked polymer technology in the oil-soluble viscosity reducer. Stearyl methacrylates (SMA), divinylbenzene (DVB), vinyl acetate (VA),1-dodecene (D) were used as monomers of polymerization, azobisisobutyronitrile (AIBN) as initiator. Two categories viscosity reducer were synthesized by solution polymerization:poly (stearyl methacrylate-divinylbenzene-vinyl acetate) polymer viscosity reducer (SDV) and poly (1-dodecenyl-divinyl benzene-vinyl acetate) polymer viscosity reducer (DVA). The viscosity reducers were characterized with infrared spectrum, scanning electron microscope, gel permeation chromatograph, thermal analyser. According to GB T265-1988Determination of kinematic viscosity and dynamic viscosity calculation of Petroleum products. Xylene and kerosene were used as the solvent viscosity reducer measured heavy oil viscosity before and after adding.The optimum reaction conditions were confirmed by single factor experiment method:reaction temperature70℃, reaction time3h, the initiator (AIBN) the amount of2%wt, the amount of ethanol solvent,100mL, n (SMA):n (DVB):n (VA)=3:0.5:3. And the effects of reaction time, initiator concentration, reaction solvent, polymerization of monomer ratios on SDV viscosity properties were discussed. Apply SDV to study the viscosity reduction of Daqing heavy oil. When the optimum dosage of250μg/g at40℃, the viscosity was reduced from142.0mm2/s to89.2mm2/s, and the viscosity reduction rate of37.2%. At50℃, the viscosity was reduced from52.3mm2/s to39.3mm2/s, and the viscosity reduction rate of24.9%. Viscosity reduction rate decreased rapidly with temperature. And it had stability of reduction effect in a long time. Results indicate the polymer has better prospects for industrial applications.The optimum reaction conditions were confirmed by orthogonal experiment: reaction temperature75℃, n (D):n (VA)=1:1, the amount of DVB2.0mL, the amount of solvent90mL, the initiator (AIBN) the amount of3%wt, reaction time of6h. The importance of the factors affecting the performance of DVA viscosity reducer: polymerization monomer ratio> initiator> solvent>polymerization time> crosslinker. When the dosage of400μg/g at50℃, the viscosity was reduced from52.3mm2/s to26.6mm2/s, the viscosity reduction rate of49.2%. DVB has better viscosity reduction rate at high temperatures. And oil-soluble viscosity reducer reduction technology and heating technology used in conjunction with providing realistic basis.According to the comparison the SEM pattern of heavy oil surface before and after adding viscosity reducer and molecular dynamics simulations. It initially validated oil-soluble viscosity reducer mechanism, viscosity reducer molecules penetrate into the heavy oil asphaltenes-glial plane pile structure, partially dismantled pile structure between the strong advantage of the ability to form hydrogen bonds and intermolecular forces aim to reduce the viscosity of heavy oil... |
PDF Full Text Request