To address the challenges associated with indoor physical simulation, theoretical formulations, and numerical simulation methods in predicting the production process of steam-assisted gravity drainage (SAGD) in dual horizontal wells, the material balance method and the principle of heat conservation were employed to analyze the SAGD development mechanism. A simplified geometric model of the SAGD steam chamber was established. Based on the characteristics of steam-assisted gravity drainage, calculation methods for key geometric parameters during the upward, lateral expansion, and downward stages of the steam chamber were derived, elucidating the developmental patterns of the SAGD steam chamber as well as the characteristics of production and water content variations. The findings indicate that the proposed model effectively simulates the mechanism of steam-assisted gravity drainage in horizontal wells, with predicted daily oil production and water content trends aligning well with actual observations. During the upward stage of the steam chamber, water content gradually decreases while oil production increases. In the lateral expansion stage, oil production significantly declines, water content rises rapidly, and overall production decreases sharply. During the downward stage, water content becomes excessively high, and the impact of steam injection on production enhancement is limited. This method, grounded in the patterns of steam chamber development, integrates material balance and heat balance considerations specific to SAGD. Compared to traditional theoretical formulas, it offers a comprehensive simulation of the entire steam chamber development process. Furthermore, in contrast to numerical simulation methods, it significantly reduces computational complexity. The research outcomes provide valuable insights for formulating development strategies and studying displacement patterns, offering important guidance for optimizing SAGD operations.