HDD dewatering bore fit with an ESP improves mining efficiency
A horizontal bore equipped with a Reda ESP™ pump (known as a bore pump in mining) resulted in significantly improved dewatering efficiency at an iron ore mine, achieving 10 times the production rate compared with that of conventional systems. The electric submersible pump (ESP) solution minimized disruptions and provided operational savings.
Fortescue Ltd, one of the world’s largest iron ore producers, faced challenges when using conventional vertical dewatering bores in the Pilbara region of Western Australia. These bores limited access to maximum water withdrawal and hindered mining efficiency because of their location inside the mining area. Additionally, the conventional pumps required multiple bores and dewatering stages to access deeper water, increasing operational complexity and costs.
Fortescue required a solution that would enhance dewatering efficiency, reduce risks to mining machinery, minimize disruptions to mining activities, and improve overall mining operations.
SLB provided an innovative solution leveraging a Reda ESP pump system, with a Reda ESP pump fit into a horizontal directional drilled (HDD) dewatering bore. This setup enabled a single lift to the surface and covered the entire dewatering demand requirements. The horizontal bore was drilled from outside the mining area, following the trajectory of the mine pit’s final plan, enabling maximum dewatering with minimal disruption to mining activities.
The ESP system lasted the life of the open pit in the Pilbara, offering a safe operating flow range from 300 to 25 L/s, which is as much as 10 times the flow capacity compared with that of the typical 25-L/s industrial pumps used in pit dewatering. This solution eventually enabled Fortescue to widen the mining area, increased the run time for pumping by more than 95%, and resulted in opex savings.
Unlike all other bore pumps, which are designed for a vertical assembly, the ESP system was purpose-designed to be installed on a slant rig (i.e., at a high-angle orientation, near horizontal). The HDD bore addressed mining operational requirements: an unhindered mining area and effective dewatering directly under the pit.
The Reda ESP pump system was chosen for its robust construction and wide operating range. The pump featured solid cast stages of mixed-flow-type flow paths, with compression impellor technology, solid ceramic journal bearings at every stage, high-temperature motor windings, self-lubricated motor bearings, oil-filled motors for best insulation, and robust fluid seals to ensure the longest run life possible in the harsh downhole conditions. The pump’s compression design (with impellors locked onto the shaft and shimmed to a high-load thrust bearing) offered a safe operating range between 10% and 110% of the pump’s best efficiency point, meeting the varying dewatering demands over the full life of the well with a single pump.
