| Popis: |
A notable portion of contemporary deep drilling rigs are still equipped with manually-operated lever-based draw-works (hoist) drum mechanical brake actuators, which are used for weight-on-bit (WoB) and rate-of-penetration (RoP) control. In order to meet increasingly stringent requirements on the WoB/RoP control performance, including completely automatic vertical drilling operation (auto-drilling), such mature drilling systems need to be retrofitted with a suitable brake actuator servo mechanism, along with appropriate WoB and RoP controls. To this end, this paper presents the development of a weight-on-bit and penetration rate control system based on electrical servomotor-based draw-works brake actuator. The control system has been arranged in the so-called cascade control system structure, with the superimposed (outermost) control loop based on the proportional-integral (PI) WoB controller, commanding the inner RoP PI controller, which in turn provides a position reference to the brake lever mechanism servo-actuator. The proposed WoB/RoP control system has been verified by simulations and experimentally on an actual oil- drilling rig equipped with electrical servodrive based-actuator of the winch drum mechanical brake. |
