Work

Research on the mechanism of water lock removal in tight sandstone gas reservoirs under microwave radiation

Year: 2026

Type: article

Abstract: Water lock in near-wellbore areas is a critical bottleneck restricting production enhancement and stable production in tight sandstone gas reservoirs, and conventional water block removal methods suffer from high energy consumption and potential secondary pollution. Microwave heating offers advantages such as selective heating and high efficiency, effectively overcoming the drawbacks of traditional water lock removal methods, while also providing dual benefits of reducing resistance in through holes and increasing permeability through fracturing. For this purpose, core samples from the main layers of the Sulige tight sandstone gas reservoir were selected. Through CT scanning, X-ray diffraction, microwave heating, and water lock physical simulation experiments, as well as temperature-stress-seepage field coupling model simulations, the modification mechanism of microwave on reservoir minerals, pore-throat structure, and percolation capacity was studied. The research results show that: (1) microwave heating can promote pore water evaporation, dehydration of mineral particles, and generate thermal stress, thereby increasing porosity and improving pore throat connectivity. The threshold is 500°C, at which point the core permeability shows significant changes. (2) Physical simulation experiments show that the optimal water block removal effect is achieved at 800W microwave power and 15 minutes heating time. Compared to unheated conditions, stable production time at different water saturations is extended by 23-48 times, and the ultimate recovery efficiency of cores with water saturations of 40%, 50%, and 60% increased by 26.55%, 19.75%, and 20.79%, respectively. (3) The temperature distribution of the core, series system development, and microwave heating water lock removal formation model established through COMSOL, fitted with experimental results, shows high model accuracy. The established formation model indicates that the actual water lock removal range is 0.6m, and the gas production after heating is 0.34×106 m3 more than without heating. The conclusion indicates that microwave heating can enhance permeability and alleviate water blockage. This research finding can provide simulation techniques and theoretical support for stable production enhancement in gas wells, guiding the implementation of field development plans.

Source: Case Studies in Thermal Engineering

DOI: 10.1016/j.csite.2026.107821