Natural gas is normally composed of three types of group components; i.e., hydrocarbons, inert and sour components.
The natural gas hydrocarbon component consists of light straight chain hydrocarbons; i.e., methane, ethane, propane, butanes, pentane, etc. The inert component consists of nitrogen and water vapors whereas the sour component normally consists of carbon dioxide (CO2), hydrogen sulfide (H2S), mercaptans, carbonyl sulfide, etc.
The inert and sour components need to be removed to control the high heating value (HHV) of sales gas to a minimum of 930 BTU/SCF to meet the desired fuel gas specification and to keep sour gas content to a permissible limit in terms of health and safety regulations.
Gas purification and treatment technologies are required for removing the inert and sour gas components. Normally, a gas containing more than 20 mol% inert and sour gases is termed a sub quality natural gas (SQNG). This type of gas is normally a lean gas with less heavy hydrocarbon components and has a lower heating value. The inert and sour components need to be removed to meet the sales gas and fuel gas specifications.
The Kingdom of Saudi Arabia has various undeveloped low BTU gas fields with significant gas reserves in the southern and northern part. Low BTU or "trash" gas monetization is required to meet the Kingdom's growing future gas demand, minimize crude oil burning and spare crude oil for export.
The Saudi Aramco Gas Operation department is responsible for future gas development as well as the operation and optimization of the existing gas plants. Due to the growth in energy demand in the kingdom, Saudi Aramco is considering and evaluating whether it should develop low BTU gases. In this regard, Saudi Aramco has undertaken several initiatives and carried out many technical and commercial studies to develop and monetize gas resources.