Study On Oil Displacing Agent With Temperature And Salt Resistance Surfactant

In this paper,?-alkenyl sulfonate(AOS)is modified to improve its resistance to calcium and magnesium ions,so that it can be better used in tertiary oil recovery and improve the recovery of high temperature and high salt reservoirs.First,allyldiethanolamine was synthesized using chloropropylene and diethanolamine as raw materials,and then allyldiethanolamine and sodium ?-alkenyl sulfonate were copolymerized.Hydroxyl groups were introduced,so binary polymer could resist calcium and magnesium ions to some degree.To introduce functional monomer acrylamide,sodium ?-alkenyl sulfonate,allyl diethanolamine and acrylamide were copolymerized.The reaction conditions of the binary polymer and the ternary polymer were optimized.The structure of the binary polymer and the ternary polymer was measured by FTIR spectra,and their molecular weight was measured by GPC.The weight average molecular weight of the binary polymer was 1376 and the weight average molecular weight of the ternary polymer was 7164.The salt resistance of the binary polymer and the ternary polymer was measured and compared with AOS.It was found that the calcium ion resistance of AOS surfactant was only 300mg/L,and the calcium ion resistance of the binary polymer was increased to 800mg/L.,The anti-calcium ion capacity of the ternary polymer was increased to 5000mg/L.The surface activity of the binary polymer and the ternary polymer was measured and compared with AOS.It was found that the surface tension of AOS was 30.477 m N/m.The surface tension of the binary polymer was 29.108 m N/m,and the surface activity was similar to that of AOS.The surface tension of the ternary polymer was 38.763 m N/m,and the surface activity became worse.Using injected water and crude oil from Qinghai Oilfield,the oil displacement performance of binary polymers and ternary polymers was measured.The compatibility between the binary polymer and the injection water of Qinghai Oilfield was good,and the compatibility between the ternary polymer and the injection water of Qinghai Oilfield was excellent.Both the binary polymer and the ternary polymer could effectively reduce the interfacial tension between the injected water and the crude oil.The interfacial tension between the binary polymer solution and the crude oil in the Zahaquan block was 0.088 m N/m,and the interfacial tension between the ternary polymer solution and crude oil in the Zhahaquan block was 0.125 m N/m.The binary polymer solution and the ternary polymer solution had good emulsification effects with the crude oil of Qinghai Oilfield.After the binary polymer solution was emulsified with the crude oil of the Zahaquan block and left for 60 minutes,the water separation rate was 12%.After the ternary polymer solution was emulsified with the crude oil of the Zahaquan block and left for 60 minutes,the water separation rate was13%.The static adsorption capacity of the binary polymer on the cuttings of the Zhahaquan block was 16.1mg/g,and the static adsorption capacity of the ternary polymer on the cuttings of the Zhahaquan block was 16.8mg/g.After treating the rock slices with crude oil in the shallow and middle layers of the Gasi,the contact angle was measured and it was found that the contact angle of distilled water on the rock slices was 126.7 ?,the contact angle of the binary polymer solution on the rock slices was 102.1 ?,and the contact angle of the ternary polymer solution on the rock slices was 91.8 ?,binary polymers and ternary polymers could reduce the lipophilicity of rock slices to varying degrees.When binary polymer solution with a concentration of0.3% was used in the Huatugou block and the injection volume was 0.3PV,the oil displacement efficiency was increased by 11.52% on the basis of water flooding;when binary polymer solution with a concentration of 0.3% was used in the shallow and middle layers of the Gasi and the injection volume was 0.3PV,the oil displacement efficiency was increased by 12.43% on the basis of water flooding.When a 0.3% ternary polymer solution was used in the Huatugou block and the injection volume was 0.3PV,the oil displacement efficiency was increased by 12.75%on the basis of water flooding;when a 0.3% ternary polymer solution was used in the Zhahaquan block and the injection volume was 0.3PV,the oil displacement efficiency was increased by 12.53% on the basis of water flooding;when a 0.3% ternary polymer solution was used in the shallow and middle layers of the Gasi and the injection volume was 0.3PV,the oil displacement efficiency was increased by 14.43%on the basis of water flooding;when a 0.3% ternary polymer solution was used in the deep layers of the Gasi and the injection volume was 0.3PV,the oil displacement efficiency was increased by 13.44% on the basis of water flooding.