X射线荧光录井技术在岩性识别中的应用——以川东北元坝地区YB10井和22井为例

Application of X-ray fluorescence logging technique in lithologic identification:A case study in wells YB10 and YB22,Yuanba region,northeast Sichuan Basin

随着川东北元坝地区空气钻、PDC和孕镶钻头+高速螺杆钻井新工艺的大量运用,钻时快、岩屑细碎甚至呈粉末状的特点,给常规录井工艺带来了岩性识别难、地层界线不易判断的问题。X射线荧光录井技术具有完全不受岩屑颗粒直径限制、分析周期短的特点。通过分析岩样中镁、铝、钾、硅、硫、钙、铁等14种元素的含量来判断岩性和识别地层,弥补了常规录井的不足。其中,YB10井在井段702～7 155m通过采用X射线荧光录井技术,现场共分析样品4 115个,根据元素含量、曲线变化特征,结合露头岩性资料,对陆相砂、泥岩和海相碳酸盐岩进行井下岩性识别,经与电测资料对比吻合度达92.60%。

New techniques such as air drilling,PDC and impregnated bit ＋ fast-spiral screw have been practiced widely in Yuanba region of the northeast Sichuan Basin;however,fast drilling and fine or even powdered detritus have made it difficult to identify lithologic characters and formation boundaries for common well-logging.The X-ray fluorescence logging technique is not restricted by small detritus size or short analysis period.It deals with the contents of 14 elements such as Mg,Al,K,Si,S,Ca and Fe in rock samples so as to analyze lithologic features and to identify formation boundaries.The new technique was practiced in well YB10.4 115 samples collected from 702-7 155 m deep were analyzed.According to element contents and curve changes,combined with outcrop lithologic data,continental sandstone and mudstone as well as marine carbonate rock were distinguished.The results were accordant with electric logging data in 92.60%.