关键词: 相关系数, 线性回归方程, 拟合随钻伽马, 岩屑XRF分析

Abstract: With the rise of rotary steering drilling technology at home and abroad, LWD gamma becomes an important reference data for horizon determination and lithology identification in drilling process, and also the main basis for tracking, comparing and adjusting well trajectory. But at present, there is a long blind area in the front of LWD instruments at home and abroad, and some wells are not suitable for running LWD gamma measuring equipment due to the complex downhole conditions. Therefore, a method to fit gamma by cuttings is urgently needed to fill this gap. On the basis of selecting six characteristic elements in rock with good correlation with electrical logging gamma by mathematical statistics method, the weight coefficient of each characteristic element was calculated by linear regression equation, and finally the fitting gamma data was obtained. Through the verification of research wells and offset wells, the coincidence degree of LWD gamma curve and electrical logging gamma curve obtained by this method is more than 95%, which can fully meet the field application.

Key words: correlation coefficient, linear regression equation, fit LWD gamma, cuttings XRF analysis