Subsea cooler

1. A subsea well fluid cooling unit comprising:

a first header pipe adapted for communication with at least one hydrocarbon well and forming a common inlet;

a second header pipe adapted for communication with a flow line and forming a common outlet, the second header pipe being substantially parallel with and positioned at a distance from the first header pipe; and

several sets of cooler coils arranged between the first and second header pipes, said several sets of cooler coils being stacked together in a frame;

wherein each set of cooler coils is individually connected to the first and second header pipes;

wherein at least one set of cooler coils comprises at least three straight pipes, at least two 180 degree bends and two connectors for connection of the set to the first and second header pipes;

wherein the first and second header pipes define a first plane, each set of cooler coils extends in a respective second plane which is perpendicular to the first plane, and the sets of cooler coils are arranged such that the second planes are parallel to each other; and

wherein the straight pipes and the bends have a constant diameter D of from 1 inch to 2 inches, the straight pipes have a length L of between 20D and 35D, the bends have a radius R of between 1.9D and 3.1D, the straight pipes are located a distance S from each other of between 3.0D and 4.0D, and the distance between the planes of adjacent sets of cooler coils is between 3.0D and 4.0D;

whereby well fluid flowing through the cooler coils between the first and second header pipes is cooled by ambient seawater.

2. Subsea cooling unit according to claim 1 , wherein the plane of the coils of at least one set is arranged transverse to the longitudinal axes of the header pipes.

3. The subsea well fluid cooling unit according to claim 1 , wherein the straight pipes and the bends have a diameter D of 1.5 inches.

4. The subsea well fluid cooling unit according to claim 1 , wherein the straight pipes have a length L of 30D.