岩样核磁共振分析方法及其在油田勘探中的应用

岩样核磁共振分析是利用氢原子核在外加磁场的作用下形成核磁共振现象的这一特性,重复测量同一样品在不同处理阶段的核磁共振信号以及该样品的横向弛豫时间(T₂)截止值,从而求取储层的孔隙度、渗透率、可动流体饱和度等地质参数的一项新的录井技术。其测量结果仅与样品的孔隙结构、孔隙流体性质及其赋存状态有关,与岩石骨架的矿物成分无关,据此可以很好地判断油田勘探工作中面临的低孔、低渗、低阻、特殊岩性储层的孔隙结构和流体性质。该项技术的应用,实现了储层物性分析从室内到钻井现场的迁移,分析对象从岩心拓展到岩屑,具有用量少、速度快、成本低、获取参数多、准确性高等优点。将其分析结果与其它测、录井资料相结合,可以更及时有效地对储集层进行评价。 

Analysis method of rock NMR and its application in oilfield exploration

Analysis of rock NMR(Nuclear Magnetic Resonance)is a new well logging technique developed in recent years,which is based on hydrogen atomic nucleus forming phenomena NMR under an additional magnetic field.Through repeatly measuring signal of NMR and cutoff value of T₂ at different processing phase,many geological parameters such as porosity,permeability,movable fluid saturation of reservoirs can be acquired.The measurement result is only related to pore structure,interstitial fluid properties and storage state,independent of mineral composition of rock frame,which is useful for the judgement of pore structure and fluid property in low porosity and low permeability,low resistivity and unusual lithology reservoir when facing difficulties in oilfield exploration.This technique realizes migration of reservoir property analysis from indoor conditions to drilling site and extension of analyzed objects from core samples to cuttings.And it has many advantages such as less sample consumption,fast analysis,lower cost,obtaining more parameters and high accuracy.The analysis result can evaluate reservoir property more effective in time combining with other data of detection logging.