AVS Multi-position, Multi-function drilling Circulating Valve
AVS – Annular Velocity System has 3 positions:
AVS in Thru-bore position. This is the standard position where all the drilling fluid is pumped through the AVS, BHA and drillbit.
AVS in Splitflow position. A portion of dilling fluid bypasses the BHA, reducing pressure losses, allowing a flow increase, maximising AV.
AVS in Bypass position. 4in² TFA are opened for rapid wellbore clean up or dumping of LCM. A ball valve closes to protect BHA components.
What is Splitflow?
Hole cleaning effectiveness is a function of; Hole angle, Mud rheology, Hole size, Drillpipe size, drillstring RPM, Mud density, Mud annular velocity, Annular eccentricity, Cutting size and ROP. Practical experimentation has shown that the most effective hole cleaning parameters are Mud Annular Velocity and Mud Density. The higher the AV, the more cuttings are removed from the wellbore. The AVS and AVD 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.
The 1st chart shows how a Splitflow of 35/65, keeps enough flow going through the BHA (800-600gpm) to power BHA and bit components but the overall flowrate is 20% higher than if all the flow was going through the BHA. The 2nd chart shows the increase in cumulative volume pumped over the example hole section. This is over 37,000bbls additional fluid pumped which means 20% more cuttings removed from the wellbore.
Features
- No drop balls, Darts or RFID tags
- Command via surface Downlink
- Simple and Rapid commands
- Throughbore at all times
- Battery powered. Low power draw
- In excess of 100 cycles
- Splitflow position with Variable
- Bypass position with BHA shutoff
- 4in² TFA in full Bypass position
Benefits
- Can be run in any inclination well
- Can be activated in Horizontak wells
- Can be run anywhere in the BHA
- Can be run below an MWD
- Splitflow maximises Annular Velocity
- Up to 200ppb LCM through Bypass
- LCM will not enter BHA in Bypass
- Cleans hole while drilling in Splitflow
- No waiting for Balls and Darts to drop
AVS Applications
The AVS has multiple application including:
- Maximise hole cleaning while drilling
- Pumping LCM
- Stabilisers preventing pack offs
- Run behind Reamer
- Subsea Riser / BOP Jetting
- Hole cleaning with Tapered String
