Analytical determination of dissolved gas concentration in water pipelines

A system comprising:

• a four-way valve comprising:
• a syringe port fluidically coupled to a source carrying water with dissolved gases produced during oil and gas production,
• a water source port fluidically coupled to a syringe configured to hold the water sample,
• an inert gas port fluidically coupled to an inert gas source, and
• an analyzer port;
• a controller connected to the four-way valve, the controller comprising:
• one or more computer systems, and
• a computer-readable medium storing instructions executable by the one or more computer systems to control the four-way valve to perform operations comprising:
• drawing a water sample through the water source port,
• flowing the water sample from the water source port to the syringe port while avoiding the inert gas port and the analyzer port, wherein the water sample is flowed to the syringe,
• after the water sample is flowed to the syringe, drawing inert gas from the inert gas source and flowing the inert gas to the syringe port and into the syringe while avoiding the water source port and the analyzer port, and
• flowing a mixture of the water sample and the inert gas from the syringe port towards the analyzer port;
• and
• an analyzer fluidically coupled to the analyzer port, the analyzer configured to receive the mixture of the water sample and the inert gas and to determine a concentration of dissolved gases in the water sample using the mixture of the water sample and the inert gas.