A hydrocarbon processing method, including processing a gaseous hydrocarbon stream to form a first production stream and a first injection stream; and compressing the first injection stream in a compressor placed at a selected location below a surface of a sea; wherein the location of the subsea compressor relative to a nearest inhabited area is determined based on a bubble plume trajectory of a model leak of the first injection stream from the compressor; and wherein the bubble plume trajectory is determined using one or more crossflow momentum parameters is disclosed herein. Also disclosed are hydrocarbon processing facilities having subsea compressors placed at such selected locations, processes for designing such hydrocarbon processing facilities, and a mathematical model useful in such methods, processes, and facilities.