Classification of drilling stick slip severity using machine learning

Rate of penetration (ROP) is a key metric used to monitor the success of drilling a well. It is directly affected by drilling vibrations since excessive vibrations result in a reduction of ROP. Vibration modeling and monitoring is a complex process often requiring many simplifying assumptions that may not always generalize to different BHAs, reservoirs, geology and formations. Therefore, it would be desirable to minimize drill string vibrations using data driven models using readily available drilling data. The hypothesis tested is the classification of stick slip severity due to drilling vibrations using open source machine learning algorithms. The stick slip index (SSI) - measuring the severity of stick slip due to drilling vibrations - is classified as low or high using machine learning classification algorithms such as logistic regression, support vector machines, random forests, gaussian mixture models and discriminant analysis. Each algorithm was evaluated based on classification accuracy, F-1 score and area under the receiver operating characteristic curve (AUC). The random forest algorithm outperforms other algorithms with an average accuracy of 90% (F-1 score of 0.91 and AUC score of 0.89). The classification model can then be used within a ROP optimization model (or framework) to determine optimal operation parameters which do not result in stick-slip conditions while drilling addressing a serious limitation of previously published ROP optimization papers.