Numerical Simulation of Tertiary CO2 Injection at Ivanic Oil Field, Croatia

摘要

Tertiary CO2 injection is planned at Ivanic oil field, Croatia, in order to recover some of more than 12×10~6 Sm~3 (75 MMSTB) of remaining oil in place. The field was discovered and put to production in 1963, secondary waterflooding was started in 1972, and today the field is facing a considerable decline in oil production and an increasing water cut.A revised geological model of Ivanic field, based on 3D seismic data acquired in 1998, was used as a ground for building a full field numerical simulation model. 40 years of production history were matched sucessfully by using black oil formulation. Compositional simulation was applied for 18 tertiary injection scenarios, which investigated impact of number and position of injection wells, number of CO2 slugs, and prior repressuring of the reservoir on the predicted production profile and final tertiary oil recovery. All tertiary injection cases were compared to the base case of continued waterflooding. Simulation results indicate possibility of recovering more t han 2.5×10~6 Sm~3 (15.7 MMSTB) of incre- mental oil in 20 years of future production. One of the possible sources of CO2 is the gas treatment plant in Molve, Croatia, which daily releases into atmosphere large quantities of carbon dioxide extracted from natural gas produced in northern Croatian gas fields. Sequestering a con- siderable amount of this CO2 in Ivani? oil field is a welcome additional benefit of the planned tertiary injection project.