Foaming Agent Developed for Gas Wells with Liquid Loading Problem Using New Surfactant and Nanotechnology

Abstract

Summary Liquid buildup in the wellbore is one of the major causes of production decline in gas wells, in which case additional energy is needed to drain off the liquid to solve this problem. Foaming agents offer a method to reduce the liquid density to make it easier to be lifted with the gas flow, unloading the accumulated liquid in gas wells. The main ingredient of foaming agents are surfactants. Foam stability is influenced by several factors, such as salinity, temperature, and pressure, so a foaming stabilizer is usually needed for a foam system. A foaming agent should be developed to form stable foams in the presence of a salt or sweet-water hydrocarbon phase at a given temperature and pressure. Recently, various kinds of foaming agents have been developed and discussed. Previous studies mainly focused on the complex interaction between an anionic surfactant and amphoteric ion surfactant; however, stability of the foam system formed by these foaming agents needs to be further improved (Nikolai et al. 2009). Therefore, development of a novel foaming agent with improved stability is necessary, especially for the application under downhole conditions. The complex interaction between the anionic and cationic surfactants is neglected in previous research. For example, the synergies between the anionic and cationic surfactants with appropriate methods can greatly improve the foam stability compared with the one-component system. A complex phase behavior and microstructure that has a high surface activity and foam stability can be obtained by the strong electrostatic interaction between the opposite charge ionic head groups and the hydrophobic interaction between the hydrocarbon groups. A gemini surfactant with a spacer can make the molecules pack tighter and increase the surfactant cohesion within the monolayer, which can greatly enhance the foam stability. The liquid film of foam formed by the surfactant is dynamically unstable because the liquid film cannot prevent the diffusion of gas, and the foam will burst quickly. However, solid films with particles adsorbed in the gas/water interface can weaken the foam drainage speed, so that the foam stability is greatly enhanced. In summary, a robust foaming agent is developed with the introduction of an anionic-nonionic surfactant complexed with a gemini cationic surfactant; moreover, nanoparticles with a certain hydrophilicity and size are also adopted as stabilizers.