An apparatus for liquefying a hydrocarbon fluid comprising: a compression system operationally configured to compress a first refrigerant stream (114/130) to produce a first compressed refrigerant stream (115/139), the compression system comprising a primary compression circuit having a plurality of compression stages (116A-D/151,154,157), each of the plurality of compression stages (116A-D/151,154,157) of the primary compression circuit being a dynamic compressor, and a secondary compression circuit having at least one compression stage (187/191), at least one of the plurality of compression stages (116D/116C-D/151) of the primary compression circuit being located in a first portion of the primary compression circuit and at least one of the plurality of compression stages (116A-C/116A-B/154,157) of the primary compression circuit being located in a second portion of the primary compression circuit, the secondary compression circuit being in fluid flow communication with the primary compression circuit and arranged in parallel with only the first portion of the primary compression circuit, the compression system being operationally configured to split the first refrigerant stream into a first portion (185A/183A/131A) that is compressed by the first portion of the primary compression circuit and a second portion (185B/183B/131B) that is compressed by the secondary compression circuit, the compression system being further operationally configured to compress all of the first refrigerant stream in the second portion of the primary compression circuit, and the compression system further comprising a driver assembly operationally configured to provide power to the plurality of compression stages of the primary compression circuit and the at least one compression stage of the secondary compression circuit; and a first heat exchanger (118/108) operationally configured to cool the hydrocarbon fluid (101/105) by indirect heat exchange between at least a portion of the first refrigerant and the hydrocarbon fluid; characterized in that: each of the least one compression stage (187/191) of the secondary compression circuit is a positive displacement compressor; and the compression system is operationally configured to split the first refrigerant stream into the first portion (185A/183A/131A) and the second portion (185B/183B/131B) such that the first portion (185A/183A/131A) comprises at least 70% of the first refrigerant stream (114/130). a compression system operationally configured to compress a first refrigerant stream (114/130) to produce a first compressed refrigerant stream (115/139), the compression system comprising a primary compression circuit having a plurality of compression stages (116A-D/151,154,157), each of the plurality of compression stages (116A-D/151,154,157) of the primary compression circuit being a dynamic compressor, and a secondary compression circuit having at least one compression stage (187/191), at least one of the plurality of compression stages (116D/116C-D/151) of the primary compression circuit being located in a first portion of the primary compression circuit and at least one of the plurality of compression stages (116A-C/116A-B/154,157) of the primary compression circuit being located in a second portion of the primary compression circuit, the secondary compression circuit being in fluid flow communication with the primary compression circuit and arranged in parallel with only the first portion of the primary compression circuit, the compression system being operationally configured to split the first refrigerant stream into a first portion (185A/183A/131A) that is compressed by the first portion of the primary compression circuit and a second portion (185B/183B/131B) that is compressed by the secondary compression circuit, the compression system being further operationally configured to compress all of the first refrigerant stream in the second portion of the primary compression circuit, and the compression system further comprising a driver assembly operationally configured to provide power to the plurality of compression stages of the primary compression circuit and the at least one compression stage of the secondary compression circuit; and a first heat exchanger (118/108) operationally configured to cool the hydrocarbon fluid (101/105) by indirect heat exchange between at least a portion of the first refrigerant and the hydrocarbon fluid; characterized in that: each of the least one compression stage (187/191) of the secondary compression circuit is a positive displacement compressor; and the compression system is operationally configured to split the first refrigerant stream into the first portion (185A/183A/131A) and the second portion (185B/183B/131B) such that the first portion (185A/183A/131A) comprises at least 70% of the first refrigerant stream (114/130). each of the least one compression stage (187/191) of the secondary compression circuit is a positive displacement compressor; and the compression system is operationally configured to split the first refrigerant stream into the first portion (185A/183A/131A) and the second portion (185B/183B/131B) such that the first portion (185A/183A/131A) comprises at least 70% of the first refrigerant stream (114/130).