Abstract
Recent field data have shown significant economic benefits are achievable when utilizing electronic autodrilling technology in conjunction with surface sensors, wellsite computers and data acquisition systems. An electronic autodrilling system was developed to provide steady-state weight at the drill bit and/or differential pressure across the motors to produce a higher quality wellbore and faster rate of penetration (ROP). Recent field applications demonstrated conclusively that the electronic autodriller not only improved control of drilling parameters such as weight on bit (WOB) and ROP, but also provided other favorable drilling attributes like controlled reaming. Longer bit runs and shorter rotating times were also observed. This study outlines the results of an advanced electronic autodriller's field application, reviews the history of various autodrilling systems, and compares and contrasts each design with respect to practical application and economic benefit.
While brake technology improvements historically have led advances in autodrilling development, recent progress in computers and programmable logic controllers (PLCs) have significantly increased the capability of automated drilling machines, culminating in multiparameter control algorithms that maximize drilling efficiency. More recently, signal processing capabilities and variable frequency drive (VFD) electronic control have been extended to allow modern digital control technologies to be combined with older band-brake type braking systems, enabling conventional drilling rigs to be equipped with a sophisticated level of control without brake replacement and the associated capital investment. The new electronic automatic drilling system, when combined with computing and data acquisition technology, optimized drilling by controlling the existing non-linear rig braking system while simultaneously examining multiple drilling parameters: WOB, ROP, differential pressure (also called delta P) and torque. Multiparameter control was proven demonstrably better than single parameter or manual control.
