Definitions for "Dissolved Gas"
Natural gas originally in solution within the reservoir crude oil. As the reservoir pressure is reduced due to production, gas is released from solution in the oil, allowing it to migrate as free gas to a wellbore and be produced or to the crest of the reservoir where it can collect and form a secondary gas cap. In addition, gas is released from solution in the oil within the wellbore as the oil is produced. Thus, most oil wells, except stripper wells producing from reservoirs where the pressure and solution gas has been depleted, produce gas with the oil. Even oil fields with no free gas originally present can produce large volumes of gas since considerable gas can be present in solution in the oil.
The amount of chemicals normally occurring as gases, such as nitrogen and oxygen, that are held in solution in water, expressed in units such as milligrams of the gas per liter of liquid. Supersaturation occurs when these solutions exceed the saturation level of the water (beyond 100 percent).
(DisGas): Dissolved gas is a measure of the pressure of dissolved gas in the water column as measured by the U.S. Army Corps of Engineers water quality monitoring site, given in mmHg. When spillway water plunges into the tailrace nitrogen is forced into the water at higher than normal levels. This condition, called supersaturation, occurs when dissolved gas pressure in the water actually exceeds the atmospheric pressure. Often collected at irregular intervals, this parameter may be missing values for one or more days, or reported values may be obviously incorrect. Daily averages are calculated from hourly values between 600 and 900 mmHg. Hourly values are reported as received from the USACE.