Developed and used for over 40 years by the Oil & Gas industry worldwide. The Sorbed Soil Gases technique has minimal environmental and social impact due to the ease of sample collection in the project area.
Sorbed Soil Gases technique analyzes the molecules of light hydrocarbons (methane, ethane, propane, butane, CH5 +) trapped in clays and carbonates of rocks, soils and sediments. It is measured in parts per million (ppm). Soil gas ratios (such as methane/ethane, ethane/propane) are compared to determine the type of hydrocarbon present in the area. Ratios between gases predict whether the source is oil, condensate, gas or from biogenic origin.
Some of the ratios accepted to determine the composition of a reservoir are C1 / C2, C3 / C4.
The technique is supported by the theory of vertical microseepage of gases from oil trapped in reservoirs. The released gases change the composition of the different layers of the subsoil during its migration up to the surface.
Samples are collected at a minimum of 50 centimeters from the surface to avoid the presence of metabolizing bacteria that can consume gas. They can be collected from seismic shotpoints or surface excavations in the field. The samples can be analyzed over a period of 12 months.
