CSCD补偿密度随钻测井仪研制

从补偿密度随钻测井仪CSCD的测井原理入手,介绍了仪器机械结构,阐述了经地层散射后伽马射线的探测、信号放大、采集及处理电路的实现和井下程序控制流程。在实钻环境中仪器受到冲击、振动、磨损和泥浆冲刷等作用,为确保放射源工作的安全,采用美国QSA公司随钻测井专用源;设计研发了双保险侧壁安装式源仓结构。由于仪器不能时刻贴井壁测量,为消除泥浆间隙带来的影响,提出适合随钻密度测井的刻度方法。2支补偿密度随钻测井仪在台2标准井完成了现场测试。试验结果表明,2支仪器工作一致性良好,测井曲线准确,符合当地地层岩性变化规律。

Development of CSCD Compensated Density LWD Tool

T he compensated density is a very important method for the evaluation of formation porosity in the logging w hile drilling . T he China‐made chemical source compensated density (CSCD) LWD tool is introduced in this paper ,including its mechanical structure ,circuit design and microcontroller program flow for realizing the gamma signal transformation ,amplification , acquisition and processing .T he special logging source from the QSA company is used ,and a new sidewall installation source‐storehouse structure of double insurance is designed for insuring safety of radioactive source w hich is subjected to shock ,vibration ,abrasion and mud erosion in the drilling environment .Since the tool cannot measure at any time without any clearance with the wall ,the compensated calibration technology of clearance medium is established to fit the drilling environment by curve fitting method .Two compensated density LWD tools completed the test in Tai 2 standard well ,and the result shows that they have good conformance and the logging curve is reliable .