Study on an all-in-one foaming agent with corrosion inhibition for air foam flooding

Abstract

Foam has been widely used in drilling, well washing, and oil driving during the development of oil and gas fields. Although air foams have been successfully employed as an enhanced oil medium, the oxygen they contain can seriously corrode piping systems, which can have a negative influence on output. This work used a combination of sodium dodecyl sulfate (SDS), dodecyl aminopropyl betaine (LAB), sodium dodecylbenzene sulfonate (SDBS), and cosurfactants to solve the problem above. The corrosion inhibitor hydrazine hydrate (N₂H₄·H₂O) was added as corrosion inhibitor. The foaming (air)-corrosion inhibitor all-in-one (SLN) was obtained with the formulation of SDS: LAB: N₂H₄·H₂O = 8:2:4. The foam volume of 0.7 % SLN was measured to be 515 mL at room temperature with a half-life of 4.1 min using the stirring method. The initial foam height of this all-in-one agent was measured to be 15.6 cm at 30 °C using the Roche foaming method. The foam height was still maintained at 15.5 cm after 20 min with a foam height retention of 99.2 %. The foam height retention rate was 50.0 % at 70 °C. Moreover, the formulation had good salt resistance to common inorganic salts in oilfield water. It should be emphasized that the SLN all-in-one agent has strong corrosion inhibition performance, and the corrosion inhibition rate can reach up to 96.9 %. The surface tension of this SLN all-in-one agent was reduced to 27.8 mN m−1 at a concentration of 0.1 %. It indicated that the all-in-one agent might increase the stability of the foam by decreasing the surface tension, thus improving the persistence of the foam and the effect of the repelling oil.