A method and system of development of a multilateral well

A system and method of developing a multilateral well for the production of formation fluids from a subterranean or subsea formation is disclosed. The multilateral well comprises a 5 completed multilateral junction having a primary wellbore access window from which a primary wellbore extends and a lateral wellbore access window from which a lateral wellbore extends. The method comprises: a) pre-installing a lateral wellbore completion string in the lateral wellbore thereby forming an annulus between the lateral wellbore completion string and the formation, the lateral wellbore completion string includes at least one ported sleeve 10 positioned adjacent to a production zone of the formation; and, b) running an intervention string through the completed multilateral junction and through the lateral wellbore completion string to reconfigure the ported sleeve between an open configuration in which the annulus is in fluid communication with an internal diameter of the lateral wellbore completion string and a closed configuration in which the lateral wellbore completion string is sealed to prevent 15 fluid communication between the internal diameter of the lateral wellbore completion string and the annulus, wherein the intervention string terminates at its lower end in a kick-over tool. - 53 -