SAGD Performance Characterization and Classification-Based Optimization in Strong Bottom Water Reservoirs

Abstract

To investigate the impact of strong bottom water layers on the development effectiveness of Steam-Assisted Gravity Drainage (SAGD) and formulate effective countermeasures, this study focuses on the A area of the L oil sand oilfield in Canada, which encounters strong bottom water and transition zones. Through systematic analysis of actual production data from 36 well pairs, the production characteristics and key control factors under the influence of strong bottom water were identified. The study found that the direct indicator of steam leakage is a sustained instantaneous water-steam ratio (iWSR) of less than 1, and summarized the typical leakage pattern characterized by “three decreases and one increase” (decrease in liquid production, oil production, and iWSR; increase in instantaneous steam-oil ratio). Based on the water avoidance height and the distribution characteristics of interlayers, the well pairs were classified into three categories, and differentiated steam injection control principles were proposed. For wells that remain ineffective after steam injection optimization, an adjustment strategy of upward sidetracking while maintaining a water avoidance height of 5 meters is recommended. Field application shows that after implementing the optimization measures, regional steam leakage volume was significantly reduced, and steam utilization efficiency was effectively improved. This study provides practical evidence based on production dynamics for risk prevention and dynamic optimization of SAGD development in strong bottom water reservoirs.