伊拉克Ahdeb油田稠油层测井识别及分布特征研究新方法

A New Method to Identify Heavy Oil and Characterize Its Distribution with Well Logs in Ahdeb Oilfield,Iraq

伊拉克Ahdeb油田Khasib油藏的开发现状迫切需要明确稠油的分布特征,以降低钻井风险。探讨了稠油层的测井响应特征,研究了稠油含量指数计算方法,在三维空间刻画出稠油的分布特征。分析稠油和轻质油基本性质的差别出发,通过理论模型分析阐述了稠油层和轻质油层在电阻率、中子孔隙度、密度以及核磁共振测井响应特征上的差异。利用阿尔奇公式计算冲洗带残余油饱和度结合中子孔隙度与密度曲线的分离幅度,定量计算了稠油含量指数,将其应用于三维地质模型中,直观地展示了稠油在各小层的分布特征。结果表明水平井轨迹穿过稠油含量指数高于0.2的区域或低产,或无法投产,生产特征与稠油分布特征完全吻合,充分证明了稠油分布特征描述的可靠性。

There are many problems in the production of Khasib reservoir in Ahdeb oilfield, Iraq. In order to lower the drilling risk of horizontal wells, the distribution of heave oil needs to be characterized. We discuss the log response of heavy oil reservoirs, calculate heavy oil index and characterize the distribution of heavy oil in a 3D geological model. We analyze the difference in the properties of heavy oil and light oil and a theoretical invasion model is proposed to illustrate the difference in resistivity, neutron porosity, bulk density and nuclear magnetic resonance logs in heave oil and light oil reservoirs. The separation magnitude of neutron and density logs combined with the residual oil saturation derived from Archie equation in the flushed zone gives a good indicator of heavy oil, which is termed as heavy oil index in this paper. The heavy oil index is input into the 3D geological model and the distribution characteristics of heave oil is visualized. The horizontal wells drilled in zones with heavy oil index greater than 0. 2 either have poor performance or cannot be put into production, which proves the reliability of the characterizationof heavy oil distribution.