The Preparation Of Amphoteric Foam Drainage Agent For Gas Well And Its Laboratory Evaluation

Nowadays,the gas wells turn into the middle and late stages of development,and the reservoir pressure and gas velocity remarkably decreased,a large amount of effusion of gas well leads to the decline of mining efficiency and affecting the normal use of gas well.According to this situation,the best way of drainage gas recovery should be chosen to make the gas well with the greatest economic benefit.The foam drainage gas recovery is widely used as a common way of drainage gas recovery because it has the advantages of simple operation and good drainage effects.The key to foam drainage is the foam drainage agent injected into wells,and the emphasis of the research is whether the foam drainage agent has excellent foaming and foam stabilization ability in complex conditions such as gas wells with condensate oil,methanol and mineralized water.Aiming at the above situation,three different types of foam drainage agents were synthesized in this paper.The main components of these three kinds of foam drainage agents are amphoteric surfactants,they have the characteristics of low toxicity,low irritation and good biodegradability on the basis of excellent foam stability and they are all environmental friendly surfactants.The amine oxide type foaming drainage agent was prepared with alkyl amide propyl dimethyl tertiary amine with oxidant.During its synthesis process,the best synthetical condition was decided by single-factor experiments,and the best synthetical condition are as follows: the molar ratio of alkyl amide propyl dimethyl tertiary amine to oxidant is 1:1.2,the quality of EDTA-2Na in the reaction system is 1.6%,the dropping time of H2O2 is 30 min,reaction time is 6h at 80?.The surface tension of this foam drainage agent in different concentrations were investigated,and the surface tension is 29.55 mN/m.The half-life and foam volume of this type of foam drainage agent in differentcondition were discussed,the influence of methanol,mineralized water,condensate oil and temperature on the foam properties were tested.The foam volume and half-life are 465 mL and 7.9 min in solution with 30% methanol.In solution with 25% methanol,the foam height after 5 min is 140 mm and the liquid carrying rate is 81%.The liquid carrying rate is 80% in 30% condensate solution,the half-life and foam volume are 5.2 min and 260 mL respectively.When salinity is 250g/L,the liquid carrying rate is 88%,and when salinity increased to 300 g/L,the liquid carrying rate decreased to 85%.The temperature tolerance of this type of foam drainage agent was as high as 80?.The intermediate product acyl propyl dimethyl tertiary amine was obtained with reaction of fatty acid and dimethyl propanediamine,and then the betaine type foam drainage agent was prepared with quaternary ammonium reaction of acyl propyl dimethyl tertiary amine and sodium chloroacetate.The best synthesis scheme was determined as follows: the molar ratio of fatty acid to dimethyl propanediamine is 1:1.1 and reaction is 8 h at 85?.The half-life was 6.9 min and the foam volume is 270 mL in mineralized water with salt content of 250 g/L.The initial foaming height is 165 mm and it decreased to 160 mm after 5 min when methanol content is 20%.The initial foaming height is 175 mm and it decreased to 155 mm after 5 min when condensate oil content is 20%.The foaming agent has excellent foaming and foam stability within the range of inorganic salt content of 300 g/L.Lauryl amine,tetradecyl amine,hexadecyl amine as raw materials respectively reacted with methacrylate,and then the reaction products were hydrolyzed in sodium hydroxide aqueous solution and sodium alkyl propionate with different carbon chain lengths was prepared.The foaming drainage agent has excellent performance when molar ratio of alkyl amine to methyl acrylate is1:1.4 and reaction time is 10 h at 60?.The foam properties of foam drainage agent in different concentration and gas flow rate were determined.The foam performance and liquid carrying rate have reached a better state when concentration of foaming drainage agent is 0.5% and the gas flow rate is 240mL/min.The half-life and the foam height of three sodium alkyl propionate were determined in methanol and condensate oil solution with different concentrations.The half-life is about 5 min when the condensate oil content is 30%,and thetetradecyl alanine sodium has good oil resistance.The half-life and the foam volume of the three sodium alkyl propionate were relatively high in 30%methanol,the foam volume is above 300 mL and the half-life is above 5 min.The foam properties were evaluated with liquid carrying rate and foam height.Under the condition of condensate oil content of 25%,tetradecyl sodium propionate has best foam performance,the foam height is 130 mm after 5 min and liquid carrying rate was 65%.Under the condition of methanol content of 25%,the foam height of these three sodium alkyl propionate are above 150 mm after 5 min and liquid carrying rate are above 60%.The amino acid type of foam drainage agent produce precipitation in the mineralized water,which shows that the salt tolerance is poor and further improvement of the synthetic scheme needs further improvement.The corrosion inhibition property of the amino acid type of foam drainage agent in hydrochloric acid solution was determined,the experimental results showed that the amino acid type of foam drainage agent has a certain corrosion inhibition property.