Royal Dutch Shell RDS.B -0.48% PLC has taken a step toward an exit from its New Zealand assets with a deal to sell its 50% stake in a natural-gas field to its local venture partner, Todd Energy.  The agreement will also see Shell take full control of a joint-venture company that operates two further gas ventures in New Zealand, simplifying Shell’s operating structure as it looks to offload the assets. Financial terms weren’t disclosed.  The sale of its stake in the Kapuni field in New Zealand’s Taranaki region to Todd Energy follows a review of operations in the country that Shell announced in December 2015 as part of efforts to refocus its natural-gas and deep-water oil businesses following a slump in oil prices.