随钻声波测井声系短节模拟样机试验研究

Experimental Study on the Simulation Prototype of Acoustic Nipples for Logging-While-Drilling(LWD)

针对随钻声波测井中换能器技术及装配的难题,研制了随钻声波测井声系短节模拟样机,基于随钻单极声波测井理论,以指向性、接收响应、单极测量功能等3个指标评价了声系短节及各组成部分的性能及特性。结果表明:发射声系以单极发射向外辐射的声场具有一定的周向均匀性,其指向性接近于一个圆,可组成单极声波发射器;接收器的接收灵敏度均值在-208.0dB附近,偏差在2.0dB以内,接收响应一致性良好,可组合相加接收单极声波信号;以单极测量功能进行的模型井整机联调试验获得了套管井波列,提取的套管波传播速度为5 245.6m/s,相对误差小于3.0%。这表明随钻声波测井声系短节具有单极发射、单极接收的测量功能,可用于模拟随钻单极声波测井,为随钻声波测井仪的研制提供试验数据。

In order to solve transducer and assembly process-related issues in acoustic logging-whiledrilling（LWD）,a simulation prototype of acoustic nipples was developed for acoustic LWD.The performance of acoustic nipple and its components was evaluated on the basis of three indexes（directivity,receiving response,and monopole measuring function.The process showed that the acoustic field generated by outward radiation of the transmitter acoustic system based on monopole excitation could be,to some extent,characterized by circumferential uniformity and its directivity pattern was close to a circle,so a monopole acoustic radiator can be developed.The average receiving sensitivity of the receivers was around-208.0dB with deviation less than 2.0dB.The receiving response characteristics of receivers were reasonably consistent,so the monopole acoustic wave could be received by adding the output of the receivers.During the integral debugging testing in a well by using the monopole measuring function,wave train in cased borehole was recorded.The extracted propagation velocity of casing wave was 5 245.6m/s with relative error below 3.0%.It demonstrated that the acoustic nipples of acoustic LWD could be used to simulate acoustic LWD for its measuring function for monopole transmission and reception,and it could provide experimental data in the development of acoustic LWD units.