Innovative approach for maximizing CO2 storage and enhancing oil recovery by co- optimization and late operation stage optimization (2016)

objective of this project is to maximize oil recovery and the total stored CO2. Continuous CO2 flooding case was used in this project as a base case reference to evaluate the different approaches in enhancing oil recovery and increasing the stored CO2. Carbonated water injection (CWI) was suggested in literature to solve the possible lack of available CO2 sources; however carbonated water requires special transportation material to alleviate the possible corrosion caused by the low pH. This would add to the total cost of the project. It was shown here that water injection into the top layer and continuous injection of CO2 into the bottom layer of the reservoir increases the stored CO2 as well as oil production. Several Co-optimization scenarios were addressed. Increasing water injection rate and injection interval increases the total stored CO2. This perhaps is due to reduction of gas-oil mobility ratio. However, in this case the ultimate oil recovery may be reduced. project addressed important factors for the optimization, using CMG GEM 2015 reservoir simulator. optimum approach with intermittent water injection and continuous CO2 injection, achieved 4.46% OOIP increase in oil recovery and 8% more CO2 stored. Reduction of CO2 utilization factor (UF) from 5.22 tCO2/Sm3 oil to 4.15 tCO2/Sm3 oil demonstrated that intermittent water injection of 500 m3/day for 3 months and then injecting water at 750 m3/day for 6 months (IW500-3-750-6) provided the best economical and practical approach in this project. I. INTRODUCTION increase of average global temperature is a concern of world leaders and scientists. Paris agreement in December 2015 (FCCC, 2015) was to hold the global average temperature well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels. Intergovernmental Panel on Climate Change (IPCC's 5th Assessment Report in 2014 Working Group III (2014)), shows that in the year 2100 the CO2 concentration in the atmosphere needs to be lower than 430 ppm in order to reach the to 1.5 °C target. Currently in April 2016 at Mauna Loa Observatory (2016) the current CO2 concentration is 407.57 ppm. From the presentation of IEA's energy outlook (Sieminski, 2016) showed that until 2040 liquid fuels consumption will maintain its position as the main source of energy in the world. It means that the world demands for petroleum energy supply will continue. Therefore, the world needs to decrease CO2 concentration in the atmosphere as well as to increase oil production. As such, an EOR approach to maximize oil recovery, yet increase the stored CO2 could help to fulfil the required world demands for energy supply and CO2 emission reduction. Oil reservoirs are attractive sites because their geology are known, therefore reducing the uncertainties associated with gas/CO2 migration. CO2 flooding of these reservoir would enhance oil production; hence cover some of the CCS and CO2 transportation costs. In CO2 EOR, the injected CO2 is partially produced back and the rest is stored in the reservoir. Jarrell et al. (2002) described this as retention: The amount of CO2 remaining in the reservoir at any given time, which equals the amount of CO2 injected less the amount of CO2 produced. For example, in Oxy's project of CO2 EOR, on the Denver Unit, for a total of 252 million tCO2 injected, of 115 million tCO2 purchased, and 137 million tCO2 produced and recycled, with 756,000 tCO2 lost from fugitive and operating emissions (Hill, Hovorka, & Melzer, 2013). From the CO2-EOR project operator point of view, CO2 retention is considered as disadvantageous, as it increases the required purchase of additional CO2 for injecting the same total CO2 cumulative injection per well pattern (Dilmore, 2010). However, the increase of CO2 availability may lead to the price decrease. In the report from IEA (2014), the projected CO2 price is expected to trending down depending on the climate change mitigation target. Under the 2° scenario it is projected that CO2 sequestration to actually add revenue to the field operator is predicted. Thus, reducing the CO2 produced and increasing the CO2 injected is one of the aims of this paper.