大庆长垣外围扶杨油层超前注水时机研究

Study on Advanced Water Injection Timing of Fuyang Reservoir in Peripheral Oilfield of Daqing Placanticline

扶杨油层岩性致密,压力传导能力差,很难补充因油井采出而导致的地层压力下降,进而导致储层物性的不可逆,借鉴国内外油田注水经验,在扶杨油层A10、B10、C10等3个区块实施超前注水,试验结果表明,开发效果明显好于同步注水和滞后注水。由于受地面注入设备、储层条件、注水成本等方面限制,超前注水时间不可能无限期延长,亟需深入、系统的研究适合扶杨油层的超前注水时机,以指导实践。在前人研究基础上,针对扶杨储层特性,推导出超前注水合理地层压力保持水平经验公式,应用物质平衡方程,确定了合理压力保持水平下的合理累计注水量,进而得到不同注水强度下超前注水时机计算公式。应用该方法对已实施超前注水区块注水时机进行计算,实际计算结果与油田开发实践基本一致。实践证明,已开发区块注水时机合理,开发效果较好,说明建立的理论方法具有较好的实用性,为超前注水技术中确定注水时机提供理论依据。

Once oil is produced ,reservoir pressure will decline for dense lithology and poor pressure trans- mission ability in Fuyang reservoir,and then reservoir physical property gets worse irreversibly.Taking the ex- perience of water injection in the oilfields at home and abroad for reference,advanced water injection was carried out in AIO,BIO and CIO three blocks in Fuyang reservoir.Experiment results show that development effect of it is much better than that of synchronization and lag water injection.Restricted by the ground in- jection equipment,reservoir conditions,and water injection cost and so on,the time of advanced water injec- tion can＇t be prolonged indefinitely and should be thoroughly and systematically studied to find suitable one for Fuyang reservoirs so as to guide practice.Based on the previous studies,the empirical formula of reason- able formation pressure level for the advanced water injection was deduced according to the characteristics of Fuyang reservoir.Material balance equation was applied for determining the reasonable cumulative water injec- tion under the reasonable pressure level,and then the computational formula for the advanced water injection timing under different injection intensity was got.The advanced water injection timing of three developed blocks was calculated by this method.The calculation results are basically identical with actual oilfield devel- opment practice,which proves that the water injection time for the developed blocks is reasonable,and the development effect is good.It also indicates that established theoretical method has good practicability and pro- vides the theory basis for the determination of advanced water injection timing.