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For gas fields, sooner or later the reservoir pressure becomes too low to maintain natural flow at a satisfactory production rate. Substantial additional reserves can be secured by enhancing recovery from fields already in operation by using increased gas recovery measures. Subsea gas compression has matured as a field development element, the benefit potential of this technology is that it eliminates the need for surface production facilities and supports production from reservoirs otherwise not seen eco nomically attractive. As a part of the subsea gas compression systems, subsea gas cooling is identified as an area with requirements to be developed. Natural convection is the motor behind the cooling, movable parts are therefore not necessary. A draft ve locity is induced by the density differences due to the temperature differences in the fluid which are caused by local heating of seawater. The main idea is to take advantage of the draft velocity and use this effect to enhance the cooling. One of the ma in technology gaps in the development of a passive cooler is the heat transfer between the cooler pipes and the seawater. This is due to uncertainties in the calculations of the draft effect and estimation thereof, uncertainties in the transition to turbu lence caused by the interaction between the pipes, and in general the complexity of the physical problem. The idea of the cooler concept is to find a geometry where natural convection from the lower cylinders is used to enhance the heat transport from the upper cylinders with a mixed free and natural convective heat transport approach. Secondly is the idea to use multiple arrays of vertical aligned horizontal cylinders in order to reduce the shear forces between the natural convective flow and the fluid a t rest. This will consequently increase the buoyancy induced flow velocity which again will increase the heat transfer from the pipes, giving a more efficient subsea cooler.