Abstract: Determining reasonable formation pressure plays an important role in improving oil recovery, reducing water consumption and casing loss rate. Whether the formation pressure is reasonable or not is also related to the stable production and economic benefits of the oilfield. For ultra⁃high water cut reservoirs, the study of formation pressure is relatively rare, and the existing methods do not take into account the influence of different viscosity, recovery degree and gas⁃oil ratio on reasonable formation pressure. Therefore, material balance method, gas⁃oil ratio dynamic data analysis method and numerical simulation method, are used to study the variation law of different viscosities, recovery degree, gas⁃oil ratio and formation pressure. Reasonable formation pressure values of each block are calculated, considering the influence of dissolved gas on crude oil viscosity and recovery factor, and the reasonable formation pressure values in the west part of central block of Daqing Oilfield are determined. The results show that the reasonable formation pressure in the west of the central region is close to the saturation pressure, the reasonable formation pressure in Sapu formation is 9.11 MPa, and the reasonable formation pressure in Gaotaizi formation is 10.12 MPa, which has important guiding significance for the later waterflooding development of Daqing Oilfield.

Key words: Reasonable formation pressure, Material balance, Gas?oil ratio, Numerical simulation

摘要： 确定合理地层压力，对提高油田采收率、减少油田耗水量、降低套损速度等方面具有重要作用。地层压力是否合理关系到油田的稳定生产和经济效益。对于特高含水期的油藏，地层压力研究比较少，已有的方法都未综合考虑不同黏度、采出程度、气油比对合理地层压力的影响。为此，运用了物质平衡法、气油比动态资料分析法、数值模拟法，开展了不同黏度、采出程度、气油比和地层压力变化规律的研究，计算了各区块合理地层压力，考察了溶解气对原油黏度的影响，进而考察对采收率的影响，确定了中区西部合理地层压力。结果表明，中区西部合理地层压力接近饱和压力，萨、葡油层合理地层压力为9.11 MPa；高台子合理地层压力为10.12 MPa，对大庆油田后期注水开发具有重要的指导意义。

关键词: 地层压力, 　物质平衡, 　气油比, 　数值模拟