考虑变表皮影响的海上油田吸水能力预测新方法

海上陆相沉积油田普遍采用注水的开发方式,深入研究注水井吸水能力变化规律,掌握注水井真实吸水能力,就能合理调整注采系统,提高注水油田最终采收率。统计发现,海上注水开发油田普遍存在吸水能力下降趋势,这一现象与理论研究不符,故利用理论公式来计算所得结果往往偏大。通过引入t时刻表皮因子S(t),模拟注水过程中流动附加阻力的变化,提出了考虑注水表皮影响的海上油田吸水能力预测新方法。海上油田注水井吸水能力主要受:(1)水驱油过程中流度比增加的正影响;(2)由于水源受限、平台水处理设施局限以及水质处理难度大等原因造成的注水表皮增加的负影响。二者的耦合最终体现为油田最终实际吸水能力的变化。与以往理论公式相比,新方法能够考虑注水过程中表皮增加带来的负影响,得到的吸水能力变化趋势更加符合现场实际,对海上注水开发油田吸水能力预测与评价有重要的指导意义。

A new prediction method for water injection capacity of offshore oilfield considering the change of water injection skin

The development mode of water injection is widely used in the offshore oil field..Study on the variation law and grasping the true water injection capacity of water injection well can reasonably adjust the injection production system and enhance the ultimate recovery of water injection oilfield. Statistics found that the decreasing trend of water injection capacity is generally existed in water injection oil field, which is not in conformity with the theoretical research. Therefore, using the theoretical formula to calculate the results are often unrealistic. By introducing the skin factor S (t) to simulate additional flow resistance during water flooding, a new method to predict the waterinjection capacity of offshore oil field considering the influence of water injection is proposed. Offshore oil field injectivity is mainly affected by, 1.positive influence: mobility ratio increased in the process of water flooding; 2.negative influence: increase of the water injection skin due to the limited water resource, platform water treatment facility limitations and the difficulty in treatment of water quality. The coupling of the two is ultimately reflected in the final actual water injection capacity of the oil field. Compared with the previous theoretical formula, the new method in this paper considering the variation of skin factor during the water flooding can accurately describe the actual water injection capacity changes, and it can be used to guide prediction and evaluation of the water injection capacity of offshore oilfield.