In the hydrocarbon industry, wellbores are drilled based upon available geological data. Many times the expectation of accessing a hydrocarbon bearing formation are realized. Unfortunately, however this is not always the case. For this reason, among others, methods and apparatus are employed to gain information as the process continues.
One of those methods and apparatus relates to determining a quantity of a gas dissolved in the drilling mud. This provides valuable information about the probability that a particular formation being accessed will bear profitable hydrocarbon levels because formation solids, where that formation is a hydrocarbon bearing one, tend to have gas dissolved therein of a type(s) associated with the existence of profitable hydrocarbons nearby. The more gas present, the more likely the formation will prove profitable.
Drilling mud has been tested for the presence of dissolved gases in the prior art but the devices used for the extraction and liberation of gas from the drilling fluid are complex, require a large amount of space and therefore must be placed some distance from the wellhead. Distance is deleterious to the process as gases come out of solution and dissipate en route to the device. This often leaves too little gas to be measurable or if still measurable causes uncertainty regarding actual amount of gas being accessed due to uncertainty regarding the precise amount of off-gassing while en route and the amount of dissipation of that released gas.