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.
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.