Gas porosity is the fraction of a rock or sediment filled with a gas.
Determining the true porosity of a gas filled formation has always been a problem in the oil industry. While natural gas is a hydrocarbon, similar to oil, the physical properties of the fluids are very different, making it very hard to correctly quantify the total amount of gas in a formation. Well logging interpretation of the amount of hydrocarbon in the pore space of a formation, relies on the fluid being oil. Gas is light compared to oil causing density logging (gamma ray emitting sensors) based measurements to produce anomalous signals. Similarly, measurements that rely on detecting hydrogen (neutron emitting sensors) can miss detecting or correctly interpreting the presence of gas because of the lower hydrogen concentration in gas, compared to oil.
By properly combining the two erroneous answers from density and neutron logging, it is possible to arrive at a more accurate porosity than would be possible by interpreting each of the measurements separately.
Read more about Gas Porosity: True Porosity of A Gas Reservoir, Gas Porosity in The Presence of Borehold Fluid Invasion Into The Reservoir
Famous quotes containing the word gas:
“Man moves in all modes, by legs of horses, by wings of winds, by steam, by gas of balloon, by electricity, and stands on tiptoe threatening to hunt the eagle in his own element.”
—Ralph Waldo Emerson (1803–1882)