Appraisal at Gazprom’s offshore South Kirinskoye field has revealed large oil reserves. Total reserves have more than doubled to 8.7 billion boe. This upgrade means South Kirinskoye has become the largest oil discovery globally in 2013. Full field development could cost US$35-40 billion. Gazprom may decide to bring in an international partner to provide the capital and technical experience. We indicatively estimate a post-tax development value of US$35 billion.