Drilling operations and the rise of auto-drill rigs require more and more sensors to pilot the top-floor operations.
Weight on bit and torque information is vital for the drilling process. Rather than trusting the hydraulic pancake at the dead-end anchor point and the traditional gauge on the top floor, top drive and rig manufacturers tend to trust other ways of establishing the actual weight of the drill string.
Using load pins to suspend the top drive is a more accurate way of measuring weight on bit as it is installed directly between the travelling block and the top drive. This means the rope reeving of the hoist has no influence on the accuracy.
Available with ATEX, IECEx (Ex ia IIC T6) and CSA (CA/US) Class 1 Div 1 certifications, the load pins also allow for the reverse direction to be measured when the top drive is pulled down by winches.
These load pins are designed to meet API 8C as they are in the load path.
A newcomer to top drive instrumentation is the top drive sub. This sub can be commissioned directly on the quill of the top drive or on a saver sub to measure tension + compression AND torque.
Available in four sizes of API thread (4½, 5½, 65/8 and 75/8), the force/torque information is transmitted wireless and battery powered. The sub instrumentation and transmission/battery is protected by a sleeve currently under Ex d certification.
There is no need to rely on the pressure transducer of the top drive’s hydraulic circuit or the power draw of electric power drives as the torque is physically measured directly between the top drive and the drill pipes.