奥陶系喀斯特地层自然伽马能谱测井曲线质量控制

Quality Control on GR Spectral Log in Ordovician Carbonate Carst Formation

自然伽马能谱测井广泛应用于塔河油田奥陶系碳酸盐岩喀斯特地层评价,但由于目的层自然伽马测量值一般低于10 API,直接使用解谱得到的铀、钍、钾含量常常导致解释错误。现从测得的铀、钍、钾含量提取出钍铀比值和铀相对比值这2个特征参数,并对其曲线进行重叠分析。该方法可快速直观地检查自然伽马能谱测井资料的质量,已广泛用于塔河油田奥陶系碳酸盐岩喀斯特地层自然伽马能谱测井曲线的质量控制中,并取得明显效果。

Natural GR spectral log has been widely used in evaluation of Ordovician carbonate carst formation in Tahe Oilfield. However, the low natural radioactivity of obiective layers, usually less than 10 API, often causes mistaken interpretation when contents of Uranium, Thorium and Kalium from analyzing the spectrum are used directly. Based on measured contents of U, Th and K, extracted are the ratio of U-to-Total and ratio of Th-to-U, and then the two ratio curves are analyzed by overlapping. This method as a quick method to check the quality of GR spectral log has been widely applied in Ordovician carbonate carst formation in Tahe Oilfield and got obvious effects.