Process for the removal of highly concentrated carbon dioxide from high-pressure natural gas

A process for disposal of highly concentrated carbon dioxide present in high-pressure natural gas which comprises:

• an absorption step of bringing high-pressure natural gas having a carbon dioxide partial pressure of 2 kg/cm.sup.2 (absolute pressure) or greater, and a pressure of 30 kg/cm.sup.2 (absolute pressure) or greater, into gas-liquid contact with a regenerated carbon dioxide-lean absorbing fluid, said carbon dioxide-lean absorbing fluid having saturated carbon dioxide absorption levels at 40.degree. C. and 120.degree. C. which differ by at least 30 Nm.sup.3 per metric ton of solvent at a carbon dioxide partial pressure of 2 kg/cm.sup.2 (absolute pressure), whereby highly concentrated carbon dioxide present in the high-pressure natural gas is absorbed into the carbon dioxide-lean absorbing fluid, to produce refined natural gas having a reduced carbon dioxide content and a carbon dioxide-rich absorbing fluid;
• a regeneration step of heating the carbon dioxide-rich absorbing fluid without depressurizing it under conditions effective to liberate high-pressure carbon dioxide having a pressure of 10 kg/cm.sup.2 (absolute pressure) or greater and carbon dioxide is dumped into an underground zone, and a carbon dioxide-lean absorbing fluid is regenerated;
• and
• a recycling step of recycling said regenerated carbon dioxide-lean absorbing fluid to said absorption step.

A process for a disposal of highly concentrated carbon dioxide present in high-pressure natural gas which comprises:

• an absorption step of bringing high-pressure natural gas having a carbon dioxide partial pressure of 2 kg/cm.sup.2 (absolute pressure) or greater, and a pressure of 30 kg/cm.sup.2 (absolute pressure) or greater, into gas-liquid contact with a regenerated carbon dioxide-lean absorbing fluid, said carbon dioxide-lean absorbing fluid having saturated carbon dioxide absorption levels at 40.degree. C. and 120.degree. C. which differ by at least 30 Nm.sup.3 per metric ton of solvent at a carbon dioxide partial pressure of 2 kg/cm.sup.2 (absolute pressure), whereby highly concentrated carbon dioxide present in the high-pressure natural gas is absorbed into the carbon dioxide-lean absorbing fluids to produce refined natural gas having a reduced carbon dioxide content and a carbon dioxide-rich absorbing fluid;
• a regeneration step of heating the carbon dioxide-rich absorbing fluid without depressurizing it under conditions effective to liberate high-pressure carbon dioxide having a pressure of 10 kg/cm.sup.2 (absolute pressure) or greater and carbon dioxide is returned to a top of an underground oil stratum, and a carbon dioxide-lean absorbing fluid is regenerated;
• and
• a recycling step of recycling said regenerated carbon dioxide-lean absorbing fluid to said absorption step.