Research Institute of Petroleum Industry (RIPI)Journal of Petroleum Science and Technology2251-659X8120180101An Estimation of Required Rotational Torque to Operate Horizontal Directional Drilling Using Rock Engineering Systems829684010.22078/jpst.2017.2199.1393ENHadi FattahiArak University of Technology, Arak, IranJournal Article20160820Horizontal directional drilling (HDD) is widely used in soil and rock engineering. In a variety of conditions, it is necessary to estimate the torque required for performing the reaming operation. Nevertheless, there is not presently a convenient method to accomplish this task. In this paper, to overcome this difficulty based on the basic concepts of rock engineering systems (RES), a model for the estimation of rotational torque to operate horizontal directional drilling is presented. The newly proposed model involves seven parameters (axial force on the cutter/bit (<em>P</em>), rotational speed (revolutions per minute) of the bit (<em>N</em>), the length of drill string in the borehole (<em>L</em>), the total angular change of the borehole (<em>K<sub>L</sub></em>), the radius for the<em> i<sup>th </sup></em>reaming operation (<em>D<sub>i</sub></em>), the mud flow rate (<em>W</em>), and the mud viscosity (<em>V</em>)) effective on required rotational torque to operate horizontal directional drilling while keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data given from nine projects. The results indicate that the RES-based model predictor with a higher coefficient of determination (<em>R<sub>2</sub></em>), a smaller mean square error (MSE), a lower root mean square error (RMSE), and a lower mean absolute percentage error (MAPE) performs better than the other models.<br />Horizontal directional drilling (HDD) is widely used in soil and rock engineering. In a variety of conditions it is necessary to estimate the torque required for performing the reaming operation. Nevertheless, there is presently not a convenient method to accomplish this task. To overcome this difficult, in this paper, based on the basic concepts of a rock engineering systems (RES), a model for the estimation of rotational torque to operate horizontal directional drilling is presented. The newly proposed model involves 7 effective parameters (axial force on the cutter/bit (P), rotational speed (revolutions per minute) of the bit (N), the length of drill string in the borehole (L), the total angular change of the borehole (KL), the radius for the ith reaming operation (Di), the mud flow rate (W) and the mud viscosity (V)) on required rotational torque to operate horizontal directional drilling with keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data given from nine projects. The results indicate that the RES based model predictor with higher coefficient of determination (R2) and less mean square error (MSE), root mean squared error (RMSE) and mean absolute percentage error (MAPE) performs better than the other models.https://jpst.ripi.ir/article_840_991a25c9a28915eff7802126adff354d.pdf