Merging Multilateral and Casing Exit Technologies to Increase Wellbore Junction Reliability by Reducing Rig and Openhole Exposure Times

摘要

This paper will reveal the challenges and benefits of merging casing exit, sealbore diverter, and multilateral casing junction technologies into one system that reduces both rig and openhole exposure times, thereby improving reliability, reducing risk, and providing a more cost- effective solution to meet the client’s needs. Typically, a multilateral junction well is accomplished by completing a casing exit with a conventional whipstock and milling bottomhole assembly (BHA), drilling the openhole, removing the whipstock, installing the sealbore diverter, and then integrating the multilateral casing junction to the sealbore diverter at the casing exit window. Accurate lateral and rotational positioning of the sealbore diverter relative to the casing exit window is required in order to properly land the multilateral junction. In addition, the time lapse between the milling-drilling operation and installation of the multilateral casing junction increases the probability of openhole collapse. A new system combines the attributes of the whipstock and sealbore diverter into one downhole assembly, which allows the whipstock to be retrieved while leaving the sealbore diverter anchored and properly oriented in the wellbore. This removes lateral and rotational orientation concerns, while also eliminating one trip downhole, thus reducing both rig and openhole exposure times. A new geometry milling BHA was also employed to maximize window length to improve ingress and egress of steerable drilling BHAs. Extensive qualification testing was performed on a horizontal skid to replicate highly deviated well conditions, and those results will be reviewed. Field trials were completed in the second quarter of 2010. Operational results will be included for discussion.