Abstract
CO₂ gas flooding in Hungary has achieved a wide range of field applications based on natural carbon dioxide resources. The oldest field-scale application has been applied in the western part of Hungary in sandstone reservoirs of Budafa and Lovászi fields, as well as in the fractured, karstic limestone and dolomite reservoirs of Nagylengyel field. After some pilot tests, the first field-scale application started in the sandstone formations of Budafa field in 1972. The produced crude is of an intermediate-paraffin character, its average density is 820 kg/m³ (41 degrees API). CO₂ gas flooding has been used as a tertiary recovery following the primary and secondary recovery, e.g., water flooding. 1,450,000 m³ (9,120,000 bbl) or incremental oil has been produced to date, resulting in 6-10% of original oil in place (OOIP) additional recovery.
Carbon dioxide was also applied in the miscible formations of Nagylengyel field containing undersaturated heavy oil. Crude oil was produced with high water cut in the 70’s. In 1980, a pilot test was started injecting high CO₂ content gas into the reservoir, creating an artificial gas cap. The field-scale application to date is 2,260,000 m³ (14,215,000 bbl). During the implementation of the carbon dioxide flooding project, several innovations had been developed both in well-technology and in surface facilities. The authors give a summary of the results and development of new technologies at the carbon dioxide flooding project.