Thermal neutron imaging log interpretation and classification methods for water-flooded reservoirs

Thermal neutron imaging system (TNIS) logging is a new nuclear logging technology that has been developed in recent years.It can detect the reservoir fluid properties and remaining oil content, which has remarkable application potential for the logging interpretation of water-flooded layers.In this study, the principles of thermal neutron imaging logging were investigated.It is pointed out that the water layer and oil layer can be identified, and the oil content of the reservoir can be indicated by the thermal neutron attenuation spectrum and captured image map.In addition, combined with the shale content and porosity calculated by conventional logging, we derived a method for calculating the remaining oil saturation using the thermal neutron macroscopic capture cross-section.On the basis of the aforementioned characteristic parameters, a cross-plot plate was established, which realized water-flooded layer identification and watered-flooded grade classification.Practical application in the Chang 8 Formation of the Ordos Basin demonstrated that thermal neutron imaging logging can identify a water-flooded layer and divide the water-flooded grade effectively, which can provide evidence for analyzing the remaining oil distribution law.The results can potentially guide actual oilfield production.