内部磁场梯度对火山岩二维核磁共振响应影响  

Effect of the Internal Magnetic Field Gradient on Two Dimensional NMR Responses in Volcanic Rock

作　　者：崔式涛 赵永杰 肖飞 王磊[4] 黄科 仁亚文 郭江峰[3] CUI Shitao;ZHAO Yongjie;XIAO Fei;WANG Lei;HUANG Ke;REN Yawen;GUO Jiangfeng(Geological Research Institution,China National Logging Corporation,Xi'an,Shaanxi 710077,China;Well Logging Key Laboratory,China National Petroleum Corporation,Xi'an,Shaanxi 710077,China;State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Tuha Branch,China National Logging Corporation,Turpan,Xinjiang 839000,China)

机构地区：[1]中国石油集团测井有限公司地质研究院,陕西西安710077 [2]中国石油天然气集团有限公司测井重点实验室,陕西西安710077 [3]油气资源与工程全国重点实验室,中国石油大学(北京),北京102249 [4]中国石油集团测井有限公司吐哈分公司,新疆吐鲁番839000

出　　处：《测井技术》2025年第1期31-39,共9页Well Logging Technology

基　　金：国家自然科学基金项目“页岩有机质核磁共振探测理论与评价方法研究”(42304118);中国石油天然气集团有限公司项目“含煤盆地富油煤岩石物理响应与测井方法研究”(D622990142);中国石油集团测井有限公司项目“测井应用基础与前沿储备技术研究”(CNLC2022-9C)。

摘　　要：二维核磁共振技术可以提供两个维度的弛豫信息,在流体识别和定量评价方面具有明显优势。火山岩储层富含顺磁性矿物,由于磁化率差异,这些顺磁性矿物会导致岩石内部存在明显的内部磁场梯度,从而影响二维核磁共振T1—T2谱和D—T2谱响应。为了提高二维核磁共振测井解释的可靠性,有必要探究内部磁场梯度对二维核磁共振响应的影响。通过数值模拟研究内部磁场梯度对火山岩二维核磁共振T1—T2和D—T2谱的影响,提出基于D—T2谱的内部磁场梯度估算方法,并通过实验验证数值模拟结果。结果表明,在二维核磁共振T1—T2谱中,随着内部磁场梯度的增加,油、气、黏土束缚水、毛细管束缚水和可动水均向T2减小方向移动,他们的T1/T2值明显增加。在二维核磁共振D—T2谱中,随着内部磁场梯度的增加,油、气、黏土束缚水、毛细管束缚水和可动水向扩散系数增大方向移动,主要是因为在数据反演时,未考虑内部磁场梯度,从而将内部磁场梯度引起的扩散弛豫衰减错误地认为是扩散系数增加导致的。基于D—T2谱数值模拟结果,验证了内部磁场梯度估算方法的准确性。Two dimensional(2D)nuclear magnetic resonance(NMR)technology can provide two kinds of relaxation information simultaneously,which has significant advantages in fluid identification and quantitative evaluation.There are rich paramagnetic minerals in volcanic reservoirs.Due to the difference in magnetic susceptibility,these paramagnetic minerals lead to a significant internal magnetic field gradient inside the rock,which affects the 2D NMR T1—T2 spectrum and D—T2 spectral response.In order to improve the reliability of 2D NMR logging interpretation,it is necessary to investigate the influence of internal magnetic field gradient on 2D NMR response.It is therefore necessary to study the effect of the internal magnetic field gradient on 2D NMR responses to improve the reliability of logging interpretation in volcanic reservoirs.The effect of the internal magnetic field gradient on 2D NMR T1—T2 and D—T2 responses was studied with the numerical simulation method,and an internal magnetic field gradient estimation method was proposed based on D—T2 spectra,and 2D NMR experiments were carried out to verify the simulation results in this paper.The results showed that oil,gas,clay bound water,capillary bound water,and movable water move towards the direction of T2 reduction,and their T1/T2 values significantly increase with the internal magnetic field gradient increases in 2D NMR T1—T2 spectra.Oil,gas,clay bound water,capillary bound water,and movable water move towards the increase direction of diffusion coefficient with the internal magnetic field gradient increases in 2D NMR D—T2 spectra.This is mainly because the internal magnetic field gradient is not considered in data inversion,leading to the erroneous assumption that the diffusion relaxation attenuation caused by the internal magnetic field gradient is due to an increase in diffusion coefficient.The accuracy of the internal magnetic field gradient estimation method was validated based the simulated D—T2 spectra.

关 键 词：二维核磁共振 T1—T2 D—T2 火山岩 内部磁场梯度 

分 类 号：P631.84[天文地球—地质矿产勘探]