Spectrum gamma ray borehole logging of MeBo sediment core Geob23725-2@en

Logging was performed with the sea floor drill rig MARUM-MeBo70 in a borehole drilled with a 103 mm diameter bit. The 1460 Slimhole Memory SGR instrument developed by ANTARES Datasystems GmbH was used. A CsI(Na) crystal with outer diameter of 37 mm and 250 mm length is used as detector. The probe provides Natural Gamma Ray counts and analyses the spectrum for the concentrations of the natural gamma ray emitters potassium, thorium and uranium with an accuracy of about 10%. The probe was deployed in the memory mode with the logging string being inserted into the drill string. The measurement was conducted as upcast hooking up the logging string with a wire inside the drill string. Wire speed was about 2 cm/s and the logging frequency was 0.5 Hz. Data Processing including the correction for bore hole diameter and signal attenuation by the drill string was conducted using the Antares software GeoBase 6.22.1本测井作业采用MARUM-MeBo70型海底钻机（sea floor drill rig MARUM-MeBo70），在直径103 mm钻头钻成的钻孔中开展。实验使用安塔雷斯数据系统有限公司（ANTARES Datasystems GmbH）研制的1460型小井眼存储式SGR（1460 Slimhole Memory SGR）仪器。该仪器采用外径37 mm、长度250 mm的掺钠碘化铯（CsI(Na)）晶体作为探测器。该探头可采集自然伽马计数，并对天然伽马发射体钾、钍、铀的浓度进行能谱分析，测量精度约为10%。实验以存储模式部署该探头，将测井串（logging string）置入钻柱（drill string）内部。本次测量通过在钻柱内穿入缆线后起吊测井串的方式完成，缆绳运行速度约为2 cm/s，测井采样频率为0.5 Hz。数据处理环节包含钻孔直径校正以及钻柱引发的信号衰减校正，处理工作依托安塔雷斯软件GeoBase 6.22.1完成。