Study On Synthesis And Property Of Modified Tea Saponin As Foaming Agent

Foam flooding is widely applied for enhanced oil recovery due to its high efficiency.As one of the cores of foaming system,foaming agent plays an important role in the effect of foam flooding.Nowadays green development has been considered by every walk of life.It is hard to ignore the impact of foaming agent towards the surface and layer of earth,as its great quantity used in oilfield.Thus,it is necessary to develop environment-friendly foaming agents.Tea saponin is a kind of nonionic natural surfactant extracted from abandoned camellia dregs,which is nontoxic,pollution-free,and easy to degradation.Tha foam produced from tea saponin has excellent performance in high temperature,high salinity and oil,which is merely influenced by quality of water,pH value and so on.However,compared with newly developed efficient foaming agents,tea saponin has lower solubility and foaming volume.In this study,chemical modification was done to improve the solubility and foaming volume of tea saponin.Succinic acid tea saponin single easter sulfonate was synthesized.Orthogonal experiment was applied to discuss the most proper reaction condition.Infrared spectrum,mass spectrum and thermal analysis were used to characterize the product.The surface tension,critical micelle concentration,critical surface tension,saturated adsorption capacity and minimum molecular occupancy area were mesured.The foam performance was tested through Waring-Blender method,and the cost of the product was estimated.The oil displacement property was studied to gain the best injection time and injection order.Tea saponin,maleic anhydride and sodium bisulfite were used as the materials of a two-step catalytic reaction including esterification and sulfonation.Nine kinds of products were obtained by orthogonal experiment design,which were name as succinic acid tea saponin single easter sulfonate.The molecular of the product was in accordance with that in theory,which was confirmed by infrared spectrum,mass spectrum and thermal analysis.The most proper conditions of the reaction were obtained through range analysis method:50°C for esterification,90°C for sulfonation,and 1:1:1.05 mole ratio of tea saponin,maleic anhydride and sodium bisulfite.The critical micelle concentration of the product was 2.699mol/L.The critical surface tension was 40.9mN/m.The saturated adsorption capacity was 0.542mmol/m~2.And the minimum molecular occupancy area was 3.062nm~2.By means of Waring-Blender method,the fittest concentration of the product was estimated as 0.50%wt,under which the volume of the foam was 580mL and the drainage half-time was 2437s.The product could still performed very well even after being aged at 180°C for 240 hours or dissolved in the water with extremely high salinity of 250000mg/L.Good foaming performance was also able to obtain even with 25%oil in the liquid.The application cost of the product was about 173.60 yuan per stere.Single model core flooding stimulation for the layer W of oilfield C showed that the most proper injection time is the half period of water flooding,and the best injection method was gas-liquid mixture.The oil recovery ratio was increased for more than 27.45%,which was totally reached up to70%.The results indicat that this kind of natural surfactant derivative has an expected prospect for oilfield development.