Foams are often employed as an efficient and cleaner method to remove the liquid accumulated at the bottom of the gas wells and promote the production of natural gas. However, the extreme conditions (e.g., high content of condensate, high salinity, high temperature, etc.) in the wells would retard the performance of the foaming agents. Usually, mixtures of different foaming surfactants were used to achieve high performances under those extreme conditions. In this paper, foams stabilized by surfactant mixtures containing alpha-olefin sulfonate (AOS), synthesized green cocamidopropyl betaine (CAPB) and modified quaternary ammonium Gemini surfactant (CAGB) in a proportion of 0.2:0.2:0.2 (wt%/wt%/wt%) were developed to evaluate their industrial application potential in gas well deliquification. The ternary surfactant (CAPB-CAGB-AOS) foam exhibited higher stability than the other dual surfactant foams and singular surfactant foams. Additionally, the foaming efficiency (defined as the ratio of the mass of water converted into foam to the mass of the initial liquid) and liquid unloading efficiency of the CAPB-CAGB-AOS mixture could be improved with the presence of condensate. Salts and methanol had a weak influence on the performance of the CAPB-CAGB-AOS foam. The introduction of ethylenediamine tetraacetic acid disodium (EDTA‧2Na) can enhance the performance of the CAPB-CAGB-AOS foam against salts. The temperature (> 60 °C) favored the foaming efficiency and liquid unloading efficiency of the CAPB-CAGB-AOS mixture, which reached up to 100% and 88.5% at 90 °C. These results indicated that the synergy effect of these three surfactants on the stability and liquid unloading efficiency of the foam can be confirmed. Moreover, the synergy effect can also be confirmed by the surface tension test , the foam's microstructure observation and the computational studies on calculated binding energies and electrostatic interactions .
Conventional foam sticks release surfactant too rapidly, resulting in a short foam duration during gas well deliquification, especially at elevated temperatures. This necessitates frequent addition of foam sticks to sustain foaming and open the wellhead . To address this issue, this paper explores the utilization of a degradable polymer and inorganic nanoparticles composite to encapsulate surfactant for prolonged and controlled release of foam, particularly at high temperatures. The nanocomposite foam sticks were prepared by blending molten degradable polymer with surfactant and various inorganic nanoparticles, which were subsequently injected and solidified in molds. The release performance of the foam sticks was evaluated based on foaming performance and surface activity over time. The nanocomposite foam sticks were characterized by infrared spectroscopy (IR), scanning electronic microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Characterization of the nanocomposite showed homogenous surfactant incorporation and increased thermostability of the solid foam sticks in the presence of inorganic nanoparticles. The foam release performance was optimized for the composite comprising the polymer, surfactant and inorganic nanoparticle fillers. The optimized nanocomposite encapsulated surfactant demonstrated controlled surfactant release, sustaining foam for over 96 h at 130 °C in brine solution . The study presents an innovative approach to enhance gas well productivity, offering a sustainable and environmentally friendly solution to the challenges of deliquification in gas wells.
危险品化学品经营许可证（带存储）