Fine Characterization Technology for Residual Gas in the SX Well Area of the Sulige Tight Sandstone Gas Reservoir

The Sulige Gas Field’s central area has entered the late stage of development, with a high overall utilization degree of reserves. However, due to the strong heterogeneity of the reservoir and the complex well network structure, the gas reserve utilization is insufficient, and there are large amounts of remaining gas between wells and within layers, with a scattered spatial distribution, making prediction challenging. To fully exploit the potential of remaining gas, targeted recovery technology strategies were developed to further improve the recovery factor by conducting fine characterization of the remaining gas. Combining previous research findings and using vertical well data, quantitative standards for identifying configuration units were established to guide the interpretation of horizontal well configuration units. Reservoir configuration analysis was conducted using both vertical and horizontal well data. Based on the configuration characterization results, a high-precision three-dimensional geological model was created, significantly improving the accuracy of inter-well predictions. Additionally, through reservoir numerical simulation, historical production fitting for the entire area was conducted, clarifying the spatial distribution of residual gas at different scales. The study results indicate that: (1) braided water channels and active water channels are the main flow resistance units for natural gas; (2) the heterogeneity of the reservoir and the spatial distribution patterns of various reservoir configuration units were finely characterized; (3) identifying the distribution characteristics and causes of residual gas, a classification evaluation of the residual gas was conducted, categorizing it into four types: flow obstruction type, unproduced perforation type, well network unregulated type, and unperforated type; (4) the utilization strategy for residual gas was clarified, and measures for enhancing potential were proposed, including side drilling of old wells, layer inspection and complementary drilling, and well network densification. These measures guided the deployment of five experimental wells in the research area.