岩心驱替实验中基于LF-NMR的油、水动态定标方法及应用

Method and application of oil and water dynamic calibration method based on LF-NMR in core displacement experiment

低场核磁共振技术可以实现岩心水驱油过程中油、水含量和分布的定量监测,对于提高采收率的研究具有重要意义。为了保证测试结果的准确性,如何进行油、水定标,建立核磁共振信号和油水质量之间的对应关系至关重要。基于低场核磁共振(LFNMR)岩心驱替实验,建立了岩心驱替过程中T2驰豫谱峰面积与岩心中油水质量或体积的对应关系,形成了一种新的动态定标方法。实验结果表明,在油和水定标中,均质岩心和非均质岩心含水质量/含油体积与对应水峰/油峰的峰面积存在正比关系,而且定标结果与常规标样的定标结果存在较大差异。利用此方法可以根据岩心驱替过程中T2驰豫谱峰面积来确定岩心中的含水和含油量,在百口泉油田X井区YFP-2泡沫体系驱油效果评价实验中应用成功,说明此动态定标方法具有很好的实际应用价值和前景。

Low-field nuclear magnetic resonance(LF-NMR)technique can be used to quantitatively monitor the contents and distribution of oil and water in cores in the process of water displacing oil and plays an important role in promoting the studies on EOR mechanisms.In order to ensure the accuracy of testing results,it is quite crucial to develop the oil and water calibration method and establish the corresponding relationships between NMR signals and oil/water quality.In this paper,the corresponding relationships between the area of T2 relaxation spectrum peak and the quality or volume of water/oil in a core in the process of core displacement were established based on LF-NMR core displacement experiment.Then,a new dynamic calibration method was developed.It is experimentally indicated that as for oil and water calibration,the water quality/oil volume in homogeneous core and heterogeneous core is proportional to the area of the corresponding water peak/oil peak and the calibration results are more deviated from the ones of conventional samples.This method can determine the contents of water and oil in a core quickly and accurately based on the area of T2 relaxation spectrum peak during core displacement.The successful application of this dynamic calibration method to evaluate the displacement effect of the YFP-2 foam system in the Well Block X of Baikouquan Oilfield indicates that it has good actual application value.