Low Temperature Progressing Cavity Pump for Antarctic Drilling Survey

Antarctica is one of the harshest environments on Earth due to severe low temperatures and isolation. The unrelenting cold affects humans, vehicles, and machinery, all must be extremely robust and resilient to survive. As most of the water is held in the ice and there is very little rainfall, Antarctica is actually classed as a desert, it is one of the driest, coldest, highest and windiest continents on Earth. 

There are currently 70 research bases located on the continent housing 10,000 researchers during the summer and around 1,000 during the winter period. These geologists, biologists and ecologists perform a wide array of surveys and experiments, each requiring different specialist and reliable equipment. 

Application Background

We were approached by a geography research professor from a UK university, he is undertaking an expedition to Antarctica and Greenland to understand how climate change has affected the ice sheets. The survey involves drilling 50 metres down through the ice to obtain rock samples that are buried beneath, this requires specialist drilling rigs that can resist the low temperatures. 

It is critical to keep the drill bits lubricated, clean of cuttings and cool while drilling, this is accomplished by pumping drilling fluid down the ice borehole. The drilling mud also has the benefit of providing stability to the well sides, controlling pressure, and delivering buoyancy. The team required a pump to recirculate the mud within the borehole, careful consideration had to be taken regarding the extreme temperature and the ice/rock chippings recirculating through the pump. 

Importance of Correct Speed Selection & Unit Sizing

After close discussions with their team, it was ascertained that a flow range of 7.5 and 11.4L/min and a pressure of 10 bar is required to sufficiently lubricate the drill bits while providing borehole stability. After supplying pumps for similar applications in the past, we selected one of our DN series of progressive cavity pumps. As the fluid contains abrasive solids and the pump is expected to work around 12 hours a day, we selected an operating speed between 52 and 150 RPM, this low speed will protect the internal components from premature wear while delivering the flow rate required. The drilling fluid is also solvent based; therefore, we manufactured the pump casing in stainless steel 316, the stator in Viton and the rotor in Hard chrome plated AISI-316 stainless steel to withstand corrosion.

Accessory & Unit Configuration for Extreme Conditions

Ambient and fluid temperatures on site can reach as low as -20°C, which is no problem for this range of pump, it is robust and reliable, exactly what this research team requires. We also supplied a control panel with variable speed drive to easily control the motor speed and therefore the flow rate. To ensure the panel withstands the extreme temperatures, we used a steel enclosure and installed an internal heater with thermostat for temperature control, this will ensure that none of the components freeze and fail. 

As the unit is installed in a remote location and accessing spare parts quickly is not simple, we added further protection by installing a mechanical seal flushing kit and dry run protection. The flushing kit provides a barrier of fluid around the mechanical seal to safeguard the seal face against rapid wear from abrasive particles. The dry run probe is located inside the stator and it detects if the temperature rises above critical levels, this then turns the motor off to stop the unit operating if no fluid is passing through the pump. This is an extremely important layer of protection as it prevents the stator and mechanical seal from damage against dry running. In addition to this, we supplied a spare stator, rotor, and mechanical seal to be left on site, this means that the engineer can quickly repair the pump if required and reduce any possible downtime. 

Some of the main benefits of our progressive cavity range are:

•         Wide range of material options, including cast iron, stainless steel 304, stainless steel 316 and bronze for the casing, stainless steel 304 and 316 for the rotor and finally NBR, EPDM or FPM for the rubber stator. 

•         Modern sealed stator design, no o-ring required.

•         Modern rubber sleeve design to improve resistance to abrasive solids.

•         Numerous sealing options, including gland packing, gland packing with flushing, single mechanical seal, single mechanical seal with quench, double mechanical seal, single or double cartridge seals and API rated sealing systems.

•         Can handle viscous fluids up to 1,000,000cp.

•         Excellent self-priming capability.

•         Reversible flow up to 3 bar as standard, Up to 12 bar with hydraulic balance.

•         Excellent at pumping fluids containing solids in suspension.

•         Excellent for shear sensitive fluids due to low pulsations.

•         Available in different versions including flanged, vertical, hopper, oenological hopper and portable for wine transfer.

•         Various accessories available, including dry running protection, bypass valve, control panel, inverter, heating jacket, grinder, and others on request. 

Here are the specifications of the supplied mud pump: