System for flushing a gas-measurement device for analyzing gas from a well, and related methods

A method for analyzing sample gases at a gas chromatograph, the method comprising:

• at a first time:
• allowing a first sample gas to move from a sample-gas line to a gas chromatograph;
• preventing a flushing gas from moving from a flushing-gas inlet to the gas chromatograph;
• and
• analyzing the first sample gas at the gas chromatograph;
• at a second time:
• preventing the first sample gas from moving from the sample-gas line to the gas chromatograph;
• and
• allowing the flushing gas to move from the flushing-gas inlet to the gas chromatograph;
• and
• at a third time:
• allowing a second sample gas to move from the sample-gas line to the gas chromatograph;
• preventing the flushing gas from moving from the flushing-gas inlet to the gas chromatograph;
• and
• analyzing the second sample gas at the gas chromatograph.

A well-gas analysis system comprising:

• a gas trap for capturing sample gases from a well, the gas trap operatively coupled to a sample-gas line;
• a first valve between the sample-gas line and a sample-gas outlet, the first valve configured to either allow or prevent gas movement between the sample-gas line and the sample-gas outlet;
• a gas analyzer operatively coupled to a testing-gas line;
• and
• a second valve between the sample-gas line, a flushing-gas inlet, and the testing-gas line, the second valve configured to allow gas movement from one of the sample-gas line or the flushing-gas inlet to the testing-gas line.