While drilling the 12 ¼” hole section, a major Norwegian operator faced severe loss of circulation. The challenge was to implement an efficient cementing operation to cure the losses, while also cleaning any remaining cement from inside of the drill pipe. This procedure would minimize NPT, prevent an unwanted and expensive trip out of hole and maintain clean internal conditions within the workstring.
DSI’s agent in Norway, TFS Services, supplied an 8 ¼” multi-cycle PBL® circulating sub, which was positioned approx. 35m above the bit. Placing the PBL® sub within the lower BHA allowed the cement to be placed as close as possible to the lost circulation zone. Once the cement had been displaced to the correct position, two sponge balls would be pumped down the workstring in order to ensure that any cement contamination was removed.
The PBL® circulating sub successfully confirmed the feasibility of performing cementing operations and cleaning the drillpipe in one single operation, eliminating at least one round trip and saving the operator approximately $200,000.