Well cleanup operations require high fluid-circulation rates for efficient cuttings transport and hole cleaning. Conventional circulation subs are deployed in drilling applications such as slim-diameter wells to deliver higher circulation rates and cuttings removal. But because these subs require multiple trips downhole for mechanical or hydraulic actuation, they add rig time and costs while drilling complex, high-angle wells. This paper reviews a radio frequency identification (RFID) circulation sub that facilitates hole cleaning via remote actuation.
The RFID circulation sub is actuated using commands communicated by RFID tags as they pass through the inside diameter (ID) of the tool string, which replaces conventional actuation methods such as ball drop or darts. This sub can be selectively actuated any number of times during the same trip downhole for enhanced operational flexibility. And because no ball seats are present, the sub maintains a full-bore ID that facilitates higher annular velocity and turbulent flow.
This paper also reviews a field application in which the RFID sub was deployed in a multi-assembly tool string to clean out a perforated 7-in. liner section and cased-hole section for a North Sea well. Once the well reached total depth, the sub was opened, closed and reopened a number of times, on command, to facilitate hole cleaning and increase fluid circulation rates to remove the wellbore debris. The RFID circulation sub helped deliver a cleaned and conditioned hole that was ready for stimulation. By completing the entire operation in a single trip, the operator saved 1.5 days of rig time.