No abstract

A surfactant containing sulfonic group was used as pretreatment agent before polymer flooding. It can form a mixed absorption layer with the polar substances of rock surface. So the wettability of rock surface can be changed to some extent, and plugging near borehole zones which was caused by polymer injection can be decreased. Compared with the effects of different wettability reversal agents on the saturated static adsorption of polymer on rock surface, a wettability reversal agent with the best effect was selected to be used as pretreatment agent for anti-clogging in polymer flooding wells. Core displacement experiment showed that the pretreatment agent can prevent the polymer adsorbing on rock surface effectively, and the plugging rate and injection pressure of polymer flooding were reduced by more than 20% and 50% respectively.

After used technology of the ASP flooding in the fourth plant of Daqing oilfield, the problem of scaling becomes serious in oil wells. The scale samples do not dissolve to acid or alkali, and it difficult to be treated with regular method, so it has influenced the normal proceeding of well production. For solving this phenomenon, the displacement experiment was proceeded to simulate the site actual oil production conditions by using the high pressure physical simulation tests. By measurement of variation law of permeability in the process of ASP flooding and pH value in produced liquid along with time, the paper predicted the starting time and duration of scaling during oil well production. And rationality of the prediction results was verified by using the local test results. Finally the prediction formulas of scaling time which the oil wells with different spacing in ASP flooding were summarized.