A client in Saudi Arabia requested that an NC50 DAV MX be positioned in the 8-3/8’’ BHA due to a possibility of losses whilst drilling the section.
The plan was to drill from 10,959 ft to 13,293 ft with 130 pcf (17.381 ppg) OBM.
During the drilling of the 8-3/8’’ hole section, the well encountered patrial losses which resulted in a well control issue due to lack of hydrostatics at depth.
The well was shut in for three days to kill the well, the mud weight was raised to 142 pcf (19 ppg). After increasing the mud weight the well saw dynamic losses (200 gpm 150 bph).
Solution & Achievement
- The decision was made to activate the DAV MX to the open position, to allow LCM to be pumped to stop / slow the losses and stabilize the well.
- At 11,660 ft, the recorded circulating pressure at 250 gpm was 1100 psi. With the drill pipe pressure bled off, the Alternative Diverter Dart (ADD) was dropped into the string and pumped down at 250 GPM. After 15 minutes the pressure increased to 2,590 psi and then the pressure dropped to 1940 psi at 450gpm, confirming that the DAV MX valve had activated and functioned to the open position. 100 bbls of 150ppb LCM was then spotted into the annulus through the ports of the DAV MX. After pumping the LCM, the well was flow checked and found to be static.
- The Universal Closing Dart (UCD) was dropped and pumped down at 300 gpm to close the DAV MX and regain conventional circulation through the lower BHA. With the DAV MX closed, the well was then displaced to 145 pcf mud to allow a trip margin and the sting was POOH. Once out of the hole, the drilling float was found to be completely washed and would not have held any pressure from below.
Key Benefits
Using the Alternative Diverter Dart (ADD) allowed the DAV MX ports to be opened and closed at surface and very quickly without the need for another dart drop. An important benefit in an unstable well.
