Molecular Simulation Of Flocculant For ASP Flooding Produced Water

Molecular Simulation of Flocculant for ASP Flooding Produced WaterMolecular simulation is a new developed technique in computational chemistry, with the development of computer technique and theoretical chemistry. It simulates the value of certain system on the molecular level adopting computational chemistry method such as quantum chemistry, molecular mechanics and molecular dynamics, including molecular design and quantitative structure activity relationship and Monte Carlo methods etc, and the advanced graphic processing and the display technique. Molecular simulation is extensively applied in petrochemicals industry, medicine industry, petroleum industry, electronics industry, automobile industry and oil field chemistry at present.In this paper composition characteristics and chemical composition and molecular construction of suspended particle in ASP flooding produced water were studied. The models of compositions of ASP flooding produced water and model of suspended particle surface were set up with the Cerius2 molecular simulation software. On the basis of acting mechanism of flocculant, the models of potential flocculants were designed, the stabile conformations were computed using molecular mechanics, molecular dynamics, Monte Carlo method etc. According to energy of interaction between potential flocculants and suspended particles, its influence on the Zeta potential of suspended particle surface was predicted. The correctness of the result of simulation was confirmed by experiments.The property of ASP flooding produced water and the direction of developing flocculant for it At present the agents of ASP in Daqing oilfield are including: partially hydrolyzed polyacrylamide (HPAM), petroleum sulphonate (alkyl benzene sulfonate), sodium hydroxide, so the ASP flooding produced water has these substances. Along them the alkyl benzene sulfonate is surfactant with negative charge, it is easily absorbed on interface between suspended particle and water, in which case the suspended particle surface will carry a great deal of negative charge, the repellant between the suspended particles and the difficulty of suspended particles gathering via collision will increase. HPAM increases the viscosity of produced water, the ascending and the sinking of oil beads will be very difficult. The alkali can increase the degree of hydrolysis of HPAM, so it causes increasing of the viscosity of the produced water.In this paper the suspended particles were separated with high-speed centrifugal machine, and were analyzed with scanning electron microscope and X-ray diffractometer. It was found that the majority of sample was amorphous substance, and the content of Si and O occupied the absolute superiority in its chemical component, sample didn't contain clay, might be contain feldspar and quartz, but less than 10%. According to the above analysis result it was judged that majority of the suspended particle in ASP flooding produced water was the noncrystalline silica.Using ASP the flooding produced water as mediums, the effects of groovy cationic flocculant were tested. It was shown that groovy cationic flocculant acted on anionic HPAM and the deposition came into being. The suspended particles in the ASP flooding produced water carry a lot of negative charge, repulse the cationic flocculant, make it ineffectively adsorb at surface of suspended particles and can not flocculate; there is strong basicity in ASP flooding produced water, under this condition the amphoteric flocculants appear character of cationic flocculants, also can not effectively adsorb at the surface of suspended particle and can not flocculate. So it was defined that the type of non-ion flocculant is the direction of molecular design of flocculant for the ASP flooding produced water.Molecular simulation of flocculant for the ASP flooding produced waterThe model of the noncrystalline silica as model of suspended particle was set up, model of hexadecyl accumbent benzene sulfonate as the model of flooding agent and the models of p...