摘要
核磁共振测井仪敏感区域的形状、探测深度以及信号强度是评价其探测特性的主要指标,而这几个主要指标完全由探头磁场分布所决定.为了在核磁共振测井仪探头设计的前期,实现对探头探测特性的客观评价,该文从核磁共振的基本条件出发,利用有限元数值模拟方法分析了MRIL-P型核磁共振测井仪探头的磁场分布,并对其磁场结构进行了优化匹配.根据核磁共振信号原理,并基于数值模拟得到的磁场优化匹配结果,进一步模拟得到MRIL-P型核磁共振测井仪敏感区分布,并验证了核磁信号强度与工作频率之间的变化关系.结果显示:在梯度磁场中,核磁信号强度主要受磁场强度的影响,并随工作频率的增大而增大,数值模拟的结果与预测结果相一致;该方法可以用来在核磁共振测井仪探头前期的设计阶段评价其探测特性,指导总体方案的设计.
The main parameters for evaluating the performance of NMR well logging Device include sensitive volume shape,depth of investigation and signal strength.These parameters are determined by the field distribution of the sensor.In order to estimate the performance of NMR well logging device during its prophase design,the field distribution of MRIL-P was simulated by the finite element method,and the field distribution was optimized.Based on the results of simulated optimization,the sensitive volume shape of MRIL-P was obtained,and the relationship between signal strength and working frequency were validated.These results indicated that,in an inhomogeneous field,the signal strength was controlled by field strength,and increased with increasing working frequency.Our results showed that this method can be used to evaluate the performance of NMR well logging device during its prophase design,and direct the overall design.
出处
《波谱学杂志》
CAS
CSCD
北大核心
2011年第1期76-83,共8页
Chinese Journal of Magnetic Resonance
基金
国家自然科学基金资助项目(41074102)
科技部国际合作资助项目(2009DFA61030)
关键词
核磁共振测井仪
敏感区
探测特性
磁场分布
数值模拟
信号强度
NMR logging device
sensitive volume detect performance
field distribution
numerical simulation
signal strength
