Study on Gas Production Mechanism of Foam Drainage and Optimization of Technological Parameters

To enhance the recovery factor of gas fields, foam drainage is an ideal method, particularly when the gas well’s production is not too low, the natural gas flow rate is sufficient, and the liquid accumulation is moderate. This study investigated the liquid carrying capacity of different foaming agents in salt solutions with varying temperatures and salinities through dynamic foam tests. By analyzing the gas quality, water quality, and process characteristics of low-yield gas wells, a new type of foaming agent was developed, which is resistant to high mineralization, oil, and methanol. The injection process parameters were then optimized to ensure effective performance. The results showed that the newly developed foaming agent could foam and carry liquid effectively under conditions with water mineralization of less than 150,000 mg/L and methanol content of less than 50%. Field tests of foam drainage gas production were conducted on-site, with significant improvements observed. During the test, the average differential pressure of the oil casing in a single well decreased by 2.9 MPa, while the average daily liquid production increased from 0.37 m³ to 0.9 m³, indicating a good drainage effect. As a result, the gas recovery rate of the well was significantly improved, with the comprehensive gas recovery rate increasing by 28.14% during the experimental period compared to the same period in previous operations. For the foam drainage process, the preferred injection method involved using an alcohol injection pump to add the foaming agent, combined with a pry-mounted foam discharge dosing truck and a foam discharge rod through a dosing cylinder.