关键词: 海上油田, 低渗透油藏, 能量保持, 地质油藏, 注水

Abstract: To settle the contradiction between “high-efficiency development” and “injection and production imbalance” that appears in the development process of offshore low-permeability oilfields, the study selects a number of controllable factors, including low-limit design of controlling targets, high-limit design of controlling targets and design of water quality target. The prediction is also made of the changes in water absorption capability. The results show that effective water injection for maintenance of formation energy is related to the geological conditions of oil reservoir, water quality control, water injector type, injection and production well pattern, and well completion design. Based on design and analysis, it is assumed that three methods can be used to keep the energy of offshore low-permeability oil reservoirs: use of horizontal wells for water injection to increase the length of water-injecting wellbore for a higher amount of injected water, multi-staged fracturing of water injectors to increase the flow area for a higher water-injecting amount, and adjustment of injection-production well pattern to increase water injectors for more water injection.

Key words: offshore oilfields, low-permeability oil reservoir, maintenance of energy, geological oil reservoirs, water injection