This wellbore branching device is installed with the casing and provides a sealed branch ready for drilling.
The time-consuming process of milling windows in casing to drill lateral branches and cementing the junction to establish mechanical and hydraulic integrity might just be coming to an end. The first step in relief from that process appears in the form of a prefabricated sealed branching system that can be run with casing.
The branching system folds into the casing when running and can be locked into kickoff position ready for the drill bit. The system was developed by a team of specialists from major manufacturing and service companies after consultations with many oil and gas producers. The device was reported at the May Offshore Technology Conference in Houston (OTC 8539 - Stracke et al). Further enhancements to the system are expected after trials are completed. In addition, other manufacturers are moving to develop competing products.
The prefabricated system provides a positive mechanical connection between the main casing and lateral liner, through-tubing access to the main bore and laterals (rigless intervention), and a seal at the junction that can be tested. A retrievable liner hanger packer assures hydraulic isolation of the lateral branch from the borehole and other laterals.
Most attractive of all are two factors: (1) the system allows full internal diameter access of the main casing after completion of all the laterals, (2) pressure and function testing of each assembly prior to installation in the well. The laterals can be installed anywhere in the wellbore, regardless of depth and radius needed. No milling of the casing is required, which helps to eliminate many of the problems associated with removing steel particles from the bore, fishing for lost milling assembly parts, and the need to sidetrack around severe problems downhole.
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