随钻核磁共振仪器缩短回波间隔方法优化设计  

Optimal design of method for shortening echo spacing by nuclear magnetic resonance while drilling

作　　者：刘伟[1,2] 张文秀[1,2] 陈文轩[1,2] 廖广志 LIU Wei;ZHANG WenXiu;CHEN WenXuan;LIAO GuangZhi(CAS Engineering Laboratory for Deep Resources Equipment and Technology,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,CAS,Beijing 100029,China;College of Geophysics,China University of Petroleum-Beijing,Beijing 102249,China)

机构地区：[1]中国科学院深地资源装备技术工程实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国石油大学(北京)地球物理学院,北京102249

出　　处：《地球物理学报》2024年第1期409-418,共10页Chinese Journal of Geophysics

基　　金：中国科学院A类战略性先导科技专项(XDA14020401);中国科学院青促会项目(2020069);中国科学院科研仪器设备研制关键技术团队项目(GJJSTD20210008)资助;国家重点研发计划项目(2019YFA0708301)。

摘　　要：核磁共振测井是一种直接探测储层孔隙流体性质的地球物理方法,随钻核磁共振技术是在钻井过程中实时获得油气藏评价参数的技术方法.面对复杂油气藏中随钻核磁共振测量问题,通过缩短脉冲序列的回波间隔,可以减少仪器测量时间,能够获得快速衰减的短弛豫组分,实现储层孔隙结构的精细表征.本文提出了一种多级能量泄放方法,能够逐级降低天线品质因数,缩短天线恢复的死区时间,在不改变回波采集信噪比的情况下,实现脉冲序列的短回波间隔采集系统设计,并在随钻核磁共振测井仪器实验样机上进行了测试验证.测试结果表明,仪器回波信号信噪比良好,振铃噪声与回波信号区分明显,测试结果与模拟仿真结果一致,能够实现短回波间隔数据采集,验证了方法的有效性和实用性.Nuclear magnetic resonance(NMR) logging is a geophysical method to directly detect the fluid properties of reservoir pores.NMR while drilling technology is a technical method for obtaining real-time evaluation parameters of oil and gas reservoirs during the drilling process.Facing the problem of NMR measurement while drilling in complex oil and gas reservoirs,the instrument measurement time can be reduced by shortening the echo spacing of the pulse sequence,and the short relaxation component with rapid decay can be obtained,thus realizing the fine characterization of the reservoir pore structure.In this paper,a multi-level energy release method is proposed,which can gradually reduce the antenna quality factor and shorten the dead-time.Without changing the signal-to-noise ratio of echo acquisition,the design of a short echo spacing acquisition system for pulse sequence is tested and verified on the experimental prototype of NMR logging while drilling instrument.The results show that the signal-to-noise ratio of the echo signal is good,the ringing noise is clearly distinguished from the echo signal.The test results are consistent with the simulation results,and the short echo spacing data acquisition can be realized,which verifies the effectiveness and practicality of the method.

关 键 词：核磁共振仪器 随钻核磁共振 回波间隔 驰豫组分 

分 类 号：P631[天文地球—地质矿产勘探]