Trouble-free brake servo/autodriller systems selected for Petrobras rigs

Lidan Engineering extended its braking reach to Brazil earlier this year with its placement of a DBS Brake Servo System and ADS Autodriller on the Petrobras V.

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Lidan Engineering extended its braking reach to Brazil earlier this year with its placement of a DBS Brake Servo System and ADS Autodriller on the Petrobras V.

The vessel, built in 1978 in Brazil, was upgraded earlier this year. Lidan's equipment was commissioned on the jackup in April.

"We work mainly with retrofitting on rigs. Practically all are equipped with drawworks with bandbrakes, manually operated through a long, heavy lever," said Thorbjörn Friman, Lidan managing director. "Lidan improves drillers' working conditions on these rigs by changing out the lever for an easy-to-control brake servo, which eliminates physical strain and fatigue injuries and increases drillers productivity."

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View of driller's work place on Petrobras V.
Click here to enlarge image

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Before Petrobras decided to order the Lidan equipment, Antonio Cardim Barbosa, rig technical manager, spent a week on a drillship equipped with the DBS Brake Servo operating off Brazil. Based on his observations and feedback from the crew concerning the system's long-term reliability and trouble-free operation. Petrobras ordered the system along with the ADS Autodriller for the Petrobras V, which will operate offshore northern Brazil.

The DBS Brake Servo is designed to mimic driller's habitual braking technique, Friman said. A dual hydraulic brake actuator is connected to the drawworks' existing brake shaft and is controlled by a small joystick. The joystick is installed either on a pedestal type console, or integrated with the armrest of a drillers' chair. The system provides the necessary feedback for the driller to continuously feel the load and, together with the Elmago brake, control hook velocity at high precision all the way down to creep speed, he said.

The ADS Autodriller is an integral function of the creep speed qualities of the DBS brake servo with a closed loop feed off control for steady rate of penetration (ROP) from 0 to 120 m/h. The unique feed off system automatically catches the braking equilibrium or "sweet spot" for starting and maintaining the drum's feed off motion. Via a control knob on the console, the driller increases the feed off rate manually until the desired weight on bit (WOB) reads on the hook load indicator. Pressing a button on the control console sets the current WOB value. The electronic WOB control automatically provides small adjustments of the feed off rate necessary to stay within narrow WOB limits. Signals from delta-p and drill string torque sensors may be integrated to the system, as these sensors relate to the control of the feed off rate the same way the WOB does. Should the string torque go high and a sudden string rise is required, the Autodriller automatically goes into override mode, Friman said.

Friman said Lidan has already delivered a second Brake Servo and Autodriller system to Petrobras – this time for the Petrobras VI jackup – and remains confident of receiving further orders from the company. The Petrobras VI equipment was due to be commissioned early this summer. Petrobras has also played an active part in installation and commissioning of the systems, he added.

For more information, contact Thorbjorn Friman, Lidan Engineering. Tel: +46 510 485570, fax: +46 510 21018, thorbjorn.friman@lidaneng.se, www.lidaneng.se.

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