Study On Foam Performance Based On Switch - Type Surfactant

Foam fluid drilling is an important auxilary means as a kind of underbalanced drilling technology, which already have the characteristics of low density,also have good foam-ability and recyclability. In order to ensure the enconomical and efficient drilling process, need to be effective recycled, foaming, defoaming, strong pollution resistance, good suspendability and small damage to the reservoir and so on. However, conventional foam fluid often can not do everything. This article selects the amidine of CO2/N2switch surfactants as foaming agent, and CO2/N2switch can be artificially controled, recycled, and is a kind of green envrionmental switch. The article is based on amidine base CO2/N2switch surfactant, testing the sensitivity and switch excitation conditions, building the foam drilling fluid system and evaluating foam performance of system.In this paper, a series of N’-long chain alkyl-N.N-dimethylacetamidinium bicarbonates were synthesised. The first stage:N’-long chain alkyl-N,N-dimethylacetamidines were synthesised. The reagents were dried before the experiment, because the reaction happened the anhydrous conditions. The reaction conditions:chloroform as solvent, n(aliphatic amines): n(DMAC)=1:2.5, adjusting the pH value of weak acid after12～14h, reaction temperature is60～65℃continued10～12h. The second stage:N’-long chain alkyl-N,N-dimethylacetamidin-ium bicarbonates were formed. The reaction happened an appropriate amount of water. The results show: N’-long chain alkyl-N,N-dimethylacetamidine is0.02mol, raw meterials ratio=N’-long chain alkyl-N,N-dimethylacetamidine:H2O=0.04(molar mass ratio), reaction time is2h, reaction temperature is45～65℃, reaction solvent is diethyl ether with an amount of20mL.CO2/N2switch evaluation method was established based on the switch feature, using the conductivity method to test the sensitivity of the switch. Temperature, acid, alkali and salt have impact on the switch. The inflatable bubble experimental device designed by myself. We gain switch excitation conditions, self circulation test of the product, analysis the influencing factors of foam performance under CO2/N2switch.On this basis, we gain unstable foam (mass fraction is0.474%DMAAB-12,the following formula quantities are mass fraction)、stable foam (0.474%DMAAB-12+0.1～0.3%HECN hard rubber foam (0.474%DMAAB-12+0.1～0.3%HEC+0.5～1.0%clay+5%NaCO3) through the optimization of treating agent and concentration, stabilizer species and concentration, clay and concentration. The recycling experiment of foam drilling fluid system found that the initial foam volume is840mL, foam half-life is500s. Foam volume decreased slightly by recycling6times, but foam stability kept. The suspension experiment for foam system shows: sedimentation rate is50～90times of water. Pollution resistance experiment shows:the system has a good ability of resistance to NaCl and CaCl2. In40～100℃, the system has a good foam-ability, foam performance is best in60～80℃. The oil resistance of this system is not strong when the concentration is more than2.00%.