岩屑XRF数据拟合随钻伽马方法研究

Study on cuttings XRF data fitting with LWD gamma method

随着国内外旋转导向钻井技术的兴起,随钻伽马成为钻井过程中层位卡取及岩性识别的重要参照数据,同时也是跟踪、对比、调整井眼轨迹的主要依据。但目前国内外随钻仪器普遍存在仪器前端盲区较长的缺点,且部分井由于井下情况复杂不适合下随钻伽马测量设备,因此亟需一种通过岩屑来拟合伽马的方法填补此空缺。在采用数理统计方法筛选出岩石中与电测伽马相关性较好的6种特征元素的基础上,通过线性回归方程方法求取各特征元素的权重系数,最终得出拟合伽马数据。通过研究井及邻井验证,该方法拟合得出的随钻伽马与电测伽马曲线吻合度达到95%以上,完全能满足现场应用。

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.