水淹层热中子成像测井解释与分级方法

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

热中子成像(TNIS)测井是近年来发展的一项核测井新技术,能够反映储层流体性质及剩余油含量,对水淹层测井解释具有较大的应用潜力。基于热中子成像测井原理,指出了通过热中子衰减谱和俘获成像图可以识别水层和油层,指示储层含油性;同时结合常规测井计算的泥质含量和孔隙度,推导了根据热中子宏观俘获截面计算剩余油饱和度的公式,并利用上述特征参数建立了交会图版,实现了水淹层识别与级别划分。在鄂尔多斯盆地长8段实际应用结果表明,热中子成像测井能够用来有效识别水淹层与划分水淹等级,为分析剩余油分布规律提供了可靠依据,对油田实际生产具有指导作用。

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.