Abstract: The invention features an offshore oil installation (1) comprising two mounting plates (6, 8) resting on the ocean bed, each mounting plate (6, 8) supporting a manifold (10; 10') connected at two ends with two respective terminal joining pieces of flexible pipe section (5, 7; 7, 9) fixed to the manifold (10; 10') substantially in the extension of each other, each manifold (10; 10') further comprising a flange for sealed joining with a pipe (12) coming from an underwater structure such as a wellhead (2; 3), the manifold (10; 10') of the two supporting plates (6; 8) being interconnected at one end by a flexible pipe section (7) and connected at the other end by two respective pipe sections (5, 9) to a surface extracting installation (4).