Abstract
Accurately understanding the recorded signals of the outcome drilling parameters, precisely linking them to the applied parameters under the determined surface and downhole conditions, correctly interpreting them for better visualization of the downhole drilling conditions to optimize the applied drilling parameters assist in achieving the best drilling performance, minimizing the costs, and significantly reducing the Non-Productive Time (NPT). The aim of this research is to analyze the responses of the drilling parameters’ signals under various status of Bit Rock Interactions (BRI) through applying an innovative laboratory technique and methodology. The aim also includes making correlations of the input and the output parameters for better understanding the parameters’ interrelationships under various status of the bit rock interactions generated by a continuance drilling through precored multi-diameter holes. The research methodology involved a comprehensive laboratory drilling tests using a Large-scale laboratory Drilling Simulator (LDS) at the drilling Technology Laboratory (DTL) of Memorial University of Newfoundland (MUN). Two rock types were used for the drilling experiments, which include granite and sandstone with high and medium strength, respectively. The whole process involved two stages. Stage one involved a pre-coring process using different diameters of impregnated coring bits. The purpose of this stage was preparing a multi-diameter hole to be tested through drilling using a 5-cutter Polycrystalline Diamond Compact (PDC) bit during stage two, where the continuance drilling occurs under a constant applied parameter of Weight On Bit (WOB) and a Revolution Per Minute (RPM). Core bits were perfectly aligned by utilizing downhole bushings with bearings for centralization and friction elimination. The applied parameters that were kept constant included WOB, RPM, formation type, and water Flow Rate (FR). The process of data analysis was conducted on the outcome drilling parameters that included torque and signal amplitude of WOB with respect to a corresponding bit rock interaction. Results showed very useful information between the responsive torque and the applied WOB signal amplitude at a constant applied WOB and other input drilling parameters. This research found novel results that show the decrease in the responsive torque when the area of contact and the bit-rock interaction increase at a constant WOB. Typically, the torque increases when the area of contact increases as a sign of more bit rock interaction involved. Research methodology, experimental procedure, data analysis and results are reported.
