Splitflow is a method whereby a percentage of the flow being pumped down the drillstring is diverted above the BHA, partially bypassing the smaller ID’s of drill collars and BHA tools such as motors, RSS and the bit which consume valuable available standpipe pressure. Enough flow and back pressure is maintained through the BHA to power tools and provide bit hydraulics. This is normally something like 70/30 split with 30% of the flow bypassing the BHA.
This allows the available surface pressure to be maximised and increase the overall flowrate. IDT engineer your drillstring hydraulics using their “Splitflow” software and an increase of up to 20% Annular Velocity can be achieved while drilling. This results in significant hole cleaning improvements while drilling. At certain points or at section TD, the AVS or AVD (if run) can be set in full bypass mode and 4in² TFA can be opened to allow higher flowrates and Annular Velocities to be used.
The AVS and AVD tools come complete with interchangeable “Diffuser” nozzles for the Splitflow position. The range of nozzles allow the flow to be split in almost any ratio depending on BHA tools being used and bit hydraulics. The Diffuser nozzles are set at 15deg angle in the inner body but the flow aperture in the main body is set at 30deg angle. This allows the flow exiting the nozzle to diffuse some energy against the tungsten carbide protective insert and ensures that flow is directed up the hole and will not wash out the hole. This has been modelled with Computational Fluid Dynamics as shown in the animation below.