自然伽马基线重叠法在同位素测井中的应用

注水后，由于地层的变化很复杂，只根据同全素示踪曲线的变化判定渗透层的吸水状况、漏窜、大孔道、套管腐蚀等往往不准确。地层吸水后，其岩层的放射性物质、孔隙结构等将发生变化；套管腐蚀以后也影响伽马射线的强度。而用不同时间的同位素测井中的自然伽以与基线重叠法可判定以上情况。该方法已在河南油田应用，效果良好。

The Application of GR Background Overlay Method to Isotope Tracer Log

Due to the changes of the formation parameters after water flooding, normally it is very difficult to determine accurately the water injection profile, leakage and bypass channel, pore path and casing errosion only by the variation of isotope tracer log. After water absorption of the formation, radioactive material in the rock and pore structure will change. Casing errosion will also affect the intensity of gamma ray. However, by the separation of GR background logs which are taken from isotope tracer logging run at different time, the water injection profile, leakage and channelling, pore path and casing errosion can be determined accurately. The GR background overlay method has been used in Henan Oilfield and good results are obtained.