DSI PBL® Bypass System saves thousands of dollars on rig NPT to operator, by allowing LCM and cement pumping in a DW well - Cuenca Salina basin in Mexico

Deep water drill ship offshore in Mexico


The DSI PBL circulating sub was requested by a major operator to be utilized in a 12 1/4” hole drilling operation in the deep waters of the Cuenca Salina basin offshore Mexico. An 8-1/4” PBL tool was placed in the BHA as a contingency for major mud losses, this tool allowed pumping of high concentration LCM (770 kg/m3) including thixotropic cement through its two ports (1.35 in diameter) with a TFA of 2.863 in2.

PBL Operation

At the depth of 4470 m, a severe mud loss (350 barrel/hour) was observed; a 2-1/2” activation ball was dropped and a LCM pill (50 ppb Form-a-Blok, 10 ppb OPTISEAL III, 20 ppb CaCO3 coarse, 10 ppb CaCO3 extra coarse) was pumped through the tool.

The PBL was activated for second time as the mud loss continued at a rate of 58 bbl/hour. The operator decided to pump a cement squeeze batch through PBL tool. It was pumped 60 bbl of 12.8 ppg tuned spacer III with 8 ppb of bridge marker II LCM, 100 bls of cement slurry H 15.8 ppg, 15 bbl of 12.8 ppg spacer followed by 15 bbl of oil base mud. The well was monitored, and still a 90-110 bbl/h loss was observed, the operator decided to pump a second cement plug with same properties as the one before. With the second cement plug the mud loss was eliminated. Two 1-3/4” steel balls were dropped to deactivate the PBL tool, with 800 gpm and 3100 psi; the PBL tool was deactivated and flow through the directional tools was successfully restored.


  • First cycle activation helped operator to reduce the mud loss rate from 350 barrel/hour to 58 bbl/hour.
  • Reduced NPT and drilling fluid volume loss for a round trip to pump aggressive LCM.
  • Second activation of the PBL tool made possible to pump two cement plugs through drill pipe and PBL without damaging the BHA (MWD and directional tools).
  • After the second cement plug, the mud loss in that drilled section was eliminated.
  • PBL tool deactivated successfully after pumping cement, directional tools worked normally, for the rest of the trip.
  • The PBL multiple activation bypass system demonstrated its value to operator by saving NPT and mud loss costs, when pumping an aggressive LCM, or even cementing multiple times. Its reliable design assures a successful function of protecting BHA components such as MWD and directional tools.

Key facts