摘要
建立了用于井下信息声传输特性研究的非周期性钻柱组合模型,并利用传递矩阵法推导出了模型的声透射系数方程,进而对周期性钻柱组合和非周期性钻柱组合的声透射系数进行了研究。结果表明:在钻柱信道中,对于周期性管柱结构,钻杆和接头的几何尺寸决定了钻柱的频带结构,并且这种频带结构呈现出周期性和对称性特征,通带和阻带交替出现,且在一个频带周期内随着频率的增加,通带先变窄再变宽,阻带则先变宽再变窄;随着钻杆根数和接头数目的增加,通带结构发生变化,通带内出现小透射峰,且小谱峰数增加。对于非周期性钻柱组合结构,钻柱中各节钻杆和接头的尺寸差异会对声传输特性造成影响,表现为通带变窄阻带变宽;结构参数中长度尺寸差异较截面尺寸差异的影响更为显著。
In order to study acoustic transmission coefficients of the periodic and the aperiodic drill-string assemblies, we established an aperiodic drill-string assembly model to characterize the downhole information transmission and then deduced an equation to calcu- late the acoustic transmission coefficient of the model by applying a transfer matrix method. The results showed that in the drill- string signal channel, as for the periodic drill-string assembly, the frequency band structure of a drill string is determined by the geo metric size of drill pipes and joints and characterized by periodicity and symmetry. The passband and stopband occur alternately and within a frequency band circle, the passband firstly narrows and then widens with the increase of frequency, while the stopband va- ries just oppositely from wideness to narrowness. With increasing the number of drill pipes and joints, the passband structure varies, e.g. some narrow transmission peaks occur within the passband and the number of small spectral peaks increases as well. As for the aperiodic drill string assembly, differences in the geometric size of individual drill pipes and joints will substantially affect acoustic transmission properties of a drill string, resulting in the passband narrower and the stopband wider. Moreover, the effect of the di mension difference in length is more prominent than that in section plane.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2012年第4期687-691,共5页
Acta Petrolei Sinica
基金
国家自然科学基金面上项目(No.50974131)
国家重点基础研究发展计划(973)项目(2010CB226706)
国家高技术研究发展计划(863)项目(2012AA091601)
高等学校博士学科点专项科研基金项目(20090133110005)资助
关键词
钻柱
周期性
声传输特性
通带
阻带
结构
drill string
periodicity
acoustic transmission characteristic
passband
stopband
structure
