Embodiments described herein provide a system and methods for the production of hydrocarbons. The method includes flowing a stream directly from a hydrocarbon reservoir to a cavern and performing a phase separation of the stream within the cavern to form an aqueous phase and an organic phase. The method also includes flowing at least a portion of the aqueous phase or the organic phase, or both, directly from the cavern to a subsurface location and offloading at least a portion of the organic phase from the cavern to a surface.