Study On Emulsified Asphalt As Water Plugging System For Thermal Horizontal Wells Of Chunguang Oilfield

Currently,thermal horizontal wells is a main method that is taken to develop heavy oil in Chunguang Oilfield.When a certain section produces water,it is impossible to use corresponding mechanical measures or seal up measures to plug water.Aiming at the problem of excessive increase in water content in thermal horizontal wells of Chunguang Oilfield,the performance of emulsified asphalt used as plugging agent in horizontal wells for thermal recovery is studied in this paper.Asphalt was the raw material,with the emulsifier formula of 2.4%sixteen alkyl three methyl ammonium chloride+0.4%eighteen alkyl three methyl ammonium chloride+0.2%emulsifier made in lab（2.4%1631+0.4%1831+0.2%TA-8）,emulsified asphalt was made in a colloid mill.Meanwhile,the influence on the emulsifying effect of temperature that asphalt was heated,asphalt’s softening point and the ratio of asphalt to water was studied.Under normal temperature,the emulsified asphalt had a great stability,which could be stable for 12 days without demusification.And the average particle size was 3.822μm,the viscosity of the emulsified asphalt was 33.44mPa·s.Besides,What’s more,the performance of temperature resistance,salt tolerance and stability mixing with sand of emulsified asphalt was studied.When the extra 1831’s concentration reached 0.075%,15%emulsified asphalt dilution could keep stable for 6hrs in 86704mg/L salinity formation,besides,15%emulsified asphalt dilution could stabilize for 6hrs at 200°C.In order to make the plugging agent have a better plugging performance at high temperature,a certain amount of styrene butadiene latex is added into emulsified asphalt as modifier,and then modified emulsified asphalt was acquired.The performance of modified emulsified asphalt was studied as well.The addition of latex increased the average particle size and viscosity slightly,and the performance of temperature resistance and salt tolerance was changed a bit.However,those influences were mere,the modified emulsified asphalt system still had a good stability and fluidity.The injection performance,plugging performance,selective plugging performance and erosion resistance of the emulsified asphalt plugging agent were studied.In order to avoid a higher injection pressure,it should be injected when the temperature was above 60°C.Meanwhile,the asphalt mass fraction in plugging agent should be at the range of 15-30%,and the permeability of target stratum should be greater than 1278×10^-3μm².Through the single tube physical simulation experiment,the formulation of emulsified asphalt plugging agent is as follows:40%emulsified asphalt raw liquid+0.075%1831+2%latex.The results showed that the plugging rate of emulsified asphalt was more than 80%at 200°C,the emulsified asphalt plugging agent had a good plugging performance and erosion resistance.The dual tubes physical simulation experiment showed that the plugging agent had a good selective plugging performance,it can be applied to water plugging in horizontal wells.