Thermal composite huff and puff synergistic system for offshore low-yield heavy oil cold production well and operation method

The invention discloses an offshore low-yield thickened oil cold production well thermal composite huff and puff synergistic system which comprises a wellhead Christmas tree, an electric pump production pipe column, a hot water injection pipeline, a mud tank, a medicament tank and a nitrogen making device, one end of the hot water injection pipeline is connected to an oil pipe wing valve, and the other end of the hot water injection pipeline is connected with platform hot water; a composite synergistic agent A is stored in the mud tank, and the mud tank is connected to the hot water injection pipeline through an agent injection pipeline A; a composite synergistic agent B is stored in the agent tank, and the agent tank is connected to the hot water injection pipeline through an agent injection pipeline B; and the nitrogen making device is connected to the sleeve wing valve through a nitrogen injection pipeline. The operation method comprises the steps that hot water, the composite synergistic agent A, the comp