The fluid produced from a hydrocarbon well is at times very hot, sometimes over one hundred degrees centigrade.  If the wells are a long distance away from a processing facility it may be necessary to boost the flow by introducing a pump in the flowline.  A pump will work better if the fluid is cooled.  This is especially important when the fluid is a gas and a compressor is employed.  The efficiency of a compressor is very dependent upon the temperature of the gas, i.e. the cooler the gas the more efficient the compressor will be. 
A well known cooling device is the radiator where a flow of cool air is forced against a piping arrangement that presents a large surface area to the air.