An apparatus for separating fluids and controlling flow of production fluid includes a diversion assembly configured to receive production fluid produced from a subterranean region, the diversion assembly including an inflow conduit in fluid communication with a first outflow conduit and a second outflow conduit, the first outflow conduit in fluid communication with a surface location. The apparatus also includes a separation assembly including a hydrophilic ribbon and an oleophilic ribbon configured to be immersed in the production fluid, at least part of the hydrophilic ribbon and the oleophilic ribbon configured to move with the production fluid, the oleophilic ribbon configured to redirect a flow of hydrocarbons into the first outflow conduit, and the hydrophilic ribbon configured to redirect a flow of water-based fluid into the second outflow conduit.