Research on productivity of medium-deep reservoirs based on stress sensitivity

Author of the article:YANG Xiaoyan, WANG Long, GONG Pingzhi, YANG Guanhong, CUI Longtao

Author's Workplace：Bohai Oilfield Research Institute, CNOOC(China) Tianjin Branch, Tianjin, 300459, China

Key Words：Medium-deep reservoirs; Stress sensitivity; Productivity; Oil-water two-phase; Experimental research

Abstract：In order to understand the effect of stress sensitivity on the productivity of a single well in a medium-deep reservoir, first, the influence of effective overpressure on permeability and oil-water phase permeability curves were studied through laboratory experiments, and the effects of stress sensitivity on permeability were quantitatively characterized based on the experimental results. According to the theory of oil-water two-phase seepage flow, a productivity equation considering the influence of stress sensitivity on the oil-water phase seepage curve is further established. Experimental and theoretical studies have shown that stress sensitivity has a greater impact on permeability and oil-water phase permeability curves, resulting in lower oil well productivity. To address the negative impact of stress sensitivity on the development of medium-deep reservoirs, strategies such as acidic fracturing for single wells, gradual recovery of oil field injection and production ratio and water injection in advance were proposed to upgrade the oil field development step by step. The research results serve as an effective guide for the development of KLA oil field development strategies, while propose related methods and schemes to restore oil field formation pressure, which is of guiding significance for the subsequent development of medium-deep reservoirs of the same nature.