**5.2 CCUS: EOR potential in the Eastern Llanos basin**

The review of progress in the different projects of the hydrocarbons sector in the Eastern Llanos basin means that currently there is sufficient infrastructure to move forward the capture and injection of CO2 for improved recovery, subtracting the construction of CO2 liquefaction facilities with sufficient

processing capacity, as well as facilities for the storage of liquid CO2. The coal power plants in the Oriental Cordillera and the natural gas deposits in the basin are potential CO2 sources.

After researching the many formations that make up the Llanos Basin, it is concluded that the Carbonera formation is the most favorable for CCUS because it has sandy interbeddings that are not being used (levels C-7, C-5, C-3, and C-1) and that they can be favorable as a storage formation due to their storage capability in a future CO2 capture project, all these are conditions to elaborated surveys of characterization of sand formation. Additionally, Carbonera is at a higher depth than the last potentially usable water source (Guayabo aquifer), isolated by clay layers that form natural hydraulic seals (levels C-2, C-4, C-6, and C-7) and covered by the regional seal of the León Formation (**Figure 6**).

The four clayey members of Carbonera add up to about 637 feet, which with low permeability provides the natural separation of the disposal area with the other units, guaranteeing the non-affectation to the "surface" aquifers in the Guayabo and Necesidad formations (**Figures 7** and **8**) [12].

In the Carbonera formation, porosities are comparatively invariant (18–23%) as well as permeable (100–3500 mD), suggesting that the units that are projected as receptors have stable petrophysical characteristics that allow the entry of a volume of injected CO2 without causing damage to the formation.

Porosities were measured through density and neutron curves taken in the wells. Regarding permeability, despite not having data in the aforementioned cores, a theoretical curve was obtained and then corrected and tuned with cores and logs from other blocks [13].

The Carbonera formation is not the only one with CO2 storage expectations, there are also the Mirador, Barco, Guadalupe, and Une formations that have even better values for a storage formation, and therefore, the best hydrocarbon reservoirs found in the Llanos basin are in these formations; however, as CO2 capture prospects, these formations could be used for secondary recovery (EOR/EGR) and obtain better results in production.

## **6. Conclusions**

The geological depository of CO2 should be considered as one of the most viable options to minimize the effects and emissions of polluting gases into the atmosphere related to fossil fuels.

At the time of reviewing the existing documentation on the method of capture and storage or sequestration of CO2, it is clear that in Colombia there is no current regulation on CCUS–EOR technologies, given that they are still in the experimental phase and the projects that are starting are pilots, or there are very few who have come to implement the technique.

The maturity of the Llanos basin and its tectonic evolution, as well as the stratigraphic and petrophysical characteristics of the large oil and gas fields with hydrodynamic capture, and good regional seals, lead to the conclusion that in the basin there are formations with good possibilities to store or sequester CO2; being the odd sandy intervals of the Carbonera formation and more specifically C-1 and C-7, the most suitable for the application of this method.

The technologies implemented within the hydrocarbons sector favor in a certain way the development of the CCUS method in Colombia, this is a considerable advantage compared to countries that do not have a presence of oil activity.

*Carbon Capture, Use and Storage (CCUS) as Enhanced Oil Recovery (EOR): Llanos Orientales… DOI: http://dx.doi.org/10.5772/intechopen.105949*
