Modular check valve system

A modular check valve system for providing back pressure to a fluid flow downhole comprising:

• a. a housing;
• b. a first cartridge housing fluidly connected to the housing, the first cartridge housing comprising:
• (i) a first poppet engaging a first cartridge housing sealing surface;
• and
• (ii) a first rod secured to the first poppet, the first rod configured to move the first poppet from a sealed position against the first cartridge housing sealing surface to an open position;
• c. an expanded cartridge housing fluidly connected to the first cartridge housing, the expanded cartridge housing comprising an expanded cartridge housing annulus;
• d. at least one cartridge insert installed in the expanded cartridge housing, the at least one cartridge insert comprising a cartridge insert poppet sealingly engaging a cartridge insert body, the cartridge insert poppet secured to a cartridge insert rod, the cartridge insert rod inserted longitudinally through the cartridge insert body and configured to move the cartridge insert poppet between a sealed position against the cartridge insert body and an open position;
• e. a second cartridge housing fluidly connected to the expanded cartridge housing, the second cartridge housing comprising:
• (i) a second poppet engaging a second cartridge housing sealing surface;
• and
• (ii) a second rod secured to the second poppet, the second rod configured to move the second poppet from a sealed position against the second cartridge housing sealing surface to an open position;
• and
• f. an exit sub fluidly engaging the expanded cartridge housing and the second cartridge housing, the exit sub comprising a sub annulus extending between an exit and an entrance.