油基钻井液对气测值的影响与校正处理

油基钻井液在高难度井、大斜度定向井和水平井钻探中被广泛应用,由于油基钻井液中含有大量石油及其衍生物,在给钻井施工带来技术优势的同时,也给气测录井带来许多不利影响。以BYP 1井和BYP 2井为例,对使用的两种油基钻井液(柴油基和白油基)进行成分分析,进而探讨其对气测全烃和组分的影响程度。针对两种不同的油基钻井液,分别建立模拟气测值的数学表达式,求得油基钻井液气测干扰值并进行剔除。该方法同样适合于其他油基钻井液分析,对各类油基钻井液干扰值的剔除具有指导意义。应用该方法既可以对正钻进的气测全烃值进行校正,也可以对早期已录取好的气测全烃值进行校正,从而为气测资料的定量评价奠定基础。

Impacts of oil-based drilling fluids on gas logging data and its correction

Oil-based drilling fluids are widely used in high challenging wells,high angle directional wells and horizontal wells,the oil-based drilling fluids contain large amounts of oil and their derivatives,while bringing technological advantages to drilling operation,they bring many negative effects on gas logging.For examples,compositional analysis was made to two types of oil-based drilling fluids（diesel based and white oil based）which were used in wells BYP 1and BYP 2,and then their impacts on gas logging total hydrocarbon and composition were discussed.For the two different oil-based drilling fluids,the authors separately set up the mathematical expressions to simulate gas logging values and obtained disturbance values of oil-based drilling fluids during gas logging and then eliminated them.The method is also suitable for analyzing other oil-based drilling fluids and can be used for reference for eliminating disturbance values in all kinds of oilbased drilling fluids.The method can not only be used to correct gas logging total hydrocarbon values while drilling,but correct the early logged total hydrocarbon values,thus laying a foundation for the quantitative evaluation of gas logging data.