Study On Nmr Response Mechanism And Evaluation Method Of Shale Oil Reservoir

In recent years,shale oil,as a special type of oil and gas reservoir,has been one of the hotspots in current exploration and development research due to the continuous improvement of proven reserves.With the large-scale exploration and development of shale oil and gas resources,fine evaluation of shale reservoirs plays an increasingly important role.Crude oil viscosity and free oil saturation are important parameters affecting oil and gas development programs,productivity,production,and recovery.They are important physical properties of fluids.However,the fluid occurrence state of shale oil reservoirs is diverse.The flow mechanism is complex,making it difficult to accurately estimate crude oil viscosity index and free oil saturation.Xinjiang Jimusaer shale oil reservoir distribution is stable,strong heterogeneity,source rock organic matter abundance is high,and organic matter type is mainly mixed.In this paper,firstly,the shale oil cores in Jimsar Sag are selected,and the NMR response mechanism of shale oil reservoirs is revealed by a series of NMR experiments.The fluid types of shale oil reservoirs are clarified,and the characterization model of fluid occurrence in shale oil reservoirs is established.The proportion of different fluid types of each component in core NMR results was further analyzed,the T₂ spectral coefficient was assigned to quantitatively evaluate fluid saturation,and the evaluation model of free oil saturation in shale oil reservoirs was established.Then,based on crude oil viscosity calculation theory,the nuclear magnetic resonance experiment results with different temperatures of shale oil cores with crude oil are analyzed,the theoretical model is improved,and the nuclear magnetic resonance evaluation method of crude oil viscosity in shale oil reservoir is established.Finally,the application of actual logging data shows that the trend of crude oil viscosity index and free oil saturation curve in shale oil reservoir is consistent with the actual oil test,production test results,and nuclear magnetic processing results,and good application results are achieved.