Standard circulating tool with Splitflow and Bypass
The AVOS tools are not activated by drop balls or darts or any other type of mechanism delivered from surface through the drillpipe. The tools are electronic and intelligent, meaning they have onboard sensors and logic and can respond to surface commands sent by “Downlinking” from surface, a coded signal to the tool via a pattern of pumps on/off and specific RPM according to a function map. The AVOS tools read the signals and shift to the particular position requested.
The AVS has 3 positions:
Throughbore – all the drilling fluid flow goes directly through the tool and to the BHA and Bit.
Splitflow – This is an Open position that can be Nozzled to allow a certain amount of the flow to be diverted into the Annulus, bypassing the BHA. This can be engineered using IDT’s SplitFlow software to allow the minimum flow requirement to power MWD / RSS / Motor / Bit hydraulics etc., and the remainder out to the annulus. This maximizes Annular Velocity for a given surface pressure.
Bypass – this position opens up a Total Flow Area (TFA) of over 4in² in the 8” tool and 2.5in² in the 7” tool, allowing maximum flowrate to the annulus for the highest Annular Velocity at the lowest surface pressure. In addition, if Lost Circulation Material (LCM) is pumped, the tool can pass 150ppb coarse LCM and a ball valve closes off the bore to ensure that the Drilling tools and Bit do not become blocked by the LCM material. The full closure is optional.