Carbon Capture, Use and Storage (CCUS) as Enhanced Oil Recovery (EOR): Llanos Orientales Basin (Colombia)

Abstract

At present, it is essential to take actions to minimize CO2 emissions into the atmosphere, and one way to use and exploit it is through the use of carbon dioxide for industry processes, such as enhanced oil recovery. By carrying out carbon capture, geological storage and improving oil recovery by applying the selection criteria to determine suitability for CO2 sequestration in the Llanos Orientales Basin as a tool to improve hydrocarbon production. It would be a first step in the sustainable development of the extractive oil industry in Colombia, which is one of the participants in greenhouse gas releases. The above can be achieved through the application of CO2–EOR processes, which are mainly miscible or immiscible methods. Finally, the importance of identifying existing CO2 sources is highlighted, in order to carry out the application of a CO2–EOR project.

1. Introduction

Global warming is an imminent threat to humanity, and it is related to CO₂ emissions in the atmosphere, which is mainly the product of the combustion of hydrocarbons (oil and gas), coal in power plants, and other industrial plants.

Considering the above, carbon capture use and geological storage (CCUS) is being considered as one of the methods to reduce greenhouse gas emissions, thus applying the methods of optimizing the operation of the different projects of enhanced oil recovery (EOR) by using carbon dioxide (CO₂), becoming the tool to improve efficiency and profitability in the production of the hydrocarbons sector. In this way, it contributes responsibly to sustainable development in energy projects [1].

The geological, geothermal, and hydraulics properties of the Eastern Llanos basin are favorable for the storage of CO₂. Considering the main criteria for the application of these projects, especially in the cases of mature deposits, it would become an applicable method to increase the production of hydrocarbons through improved recovery and thus increase their useful life.

2. Current situation of CO₂: EOR

Enhanced oil recovery is done by the use of CO₂ (CO₂–EOR). It is a kind of CCUS technology. This practical application was started and improved as early as 1972, directing to improve oil recovery through the introduction of CO₂ into oil reservoirs. (Figure 1) [2].

Figure 1.

Number of EOR projects in operation globally [2].

The current and active projects, where CO₂–EOR is applied, have been developed mostly in the United States (Permian Basin, Gulf Coast, and the Rockies (see Figure 1.)), and in Canada in better proportion with seven projects of injection of CO₂, plus another additional injection of acid gases; however, it is relevant to indicate that this method has also been practiced for several decades in Turkey and Hungary, and there are new projects in various stages of development in Asia, the Middle East, and the North Sea. On a pilot scale, there are also developments in China, Brazil (onshore – Miranga field), and Abu Dhabi.

As a consequence of the advantages of this method, as part of the KAPSARC data source, in 2020, there are 38 CO₂–EOR large-scale projects in different project life cycle stages [3], and according to International Energy Agency (IEA), the entire amount of CCUS programs in industry and fuel transformation increase to 19 in 2020 when the two Alberta Carbon Trunk Line programs in Canada started activity (Figure 2) [2].

Figure 2.

Sizeable CO₂–EOR projects in different stages by applied industries [5].

According to the information updated in 2020, it was identified that there was a decrease in the U.S. of approximately 47% of CO₂ supplied for EOR projects compared to that supplied in 2019, with one of the possible causes being the decline in oil and gas prices. However, the increment in prices in 2021 may lead to an increase in oil production through EOR–CO₂ projects [4].

Figure 2 indicates that the Century CO₂–EOR plant in Texas is one of the projects with the most capacity per year. It was started in 2010 with a reduced capture capacity, but the volume was increased to its full capacity of 8.4 Mt./year in 2012 [5].

Also, the Shute Creek Gas processing installation in Wyoming, USA, has been handling natural gas from the LaBarge field beginning in 1986. Before improving it, H₂S was separated along with approximately 0.4 Mt./a of CO₂. In 2010, an expansion of the plant’s capacity was finished, getting a capture capacity of 7 Mt./a of CO₂ [5].

Another project is the Val Verde Natural Gas Facility in Texas, USA. Currently, five different gas processing installations in the Val Verde area get about 1.3 Mt./yr. of CO₂ for use in EOR facilities at the Sharon Ridge oil field. The CO₂ concentration of the incoming gas stream at the Val Verde plant ranges from 25 to 50% [5].

Under evaluation phases, there are eight big CO₂–EOR projects. Nearly 63% of them are planned in China irrespective of the reality that tight continental geology and heavier oil are important factors [5].

2.1 Criteria for the choice of the geographical area for the storage of CO₂

According to Bachu [6], it is necessary to evaluate, at the basin scale, the suitability for CO₂ sequestration in sedimentary rocks, among which are the following aspects:

1. Geological criteria

2. Geothermal criteria

3. Hydrodynamic criteria

Considering the above, a roadmap is proposed for the implementation of this method in geological media [7]:

Assessment of suitability at the regional level, to determine the areas of a basin that could become suitable and the means of storage, which include the following

Inventory of feasible sites for CO₂storage, which initially requires the identification of the main sources of CO₂, followed by a local-level characterization considering the pressure and temperature in situ, as well as properties of hydrocarbons.

Safety of CO₂storage operations, where it is secure that there will be no upward migration of CO₂ and leakage to other beds during or after introduction, which could occur through open geological faults and natural or man-induced fractures, irrespective of storage media.

Storage capacity, for EOR operations in mature stage oil and gas deposits, storage pore volume, grade of water penetration as a result of oil production, and CO₂ solubility are crucial components in judging storage capacity.

3. Benefits of lifecycle emissions on CO₂ reduction of CO₂: EOR projects

As reported by the International Energy Agency (IEA), the hydrocarbons industry is one of the world’s pioneers in the development and deployment of CO₂ capture. Currently, most of the CO₂ injected in CO₂–EOR projects is produced from naturally occurring subsurface CO₂ deposits. It is clear that the use of natural sources does not provide any advantage in the emissions degree of the oil produced. In the United States, more than 70% of the CO₂ dispensed today for CO₂–EOR is from natural sources [8].

Nevertheless, there are some programs that use CO₂ captured from man-made sources for EOR—the Century and Petra Nova plants in Texas. These are two bigger installations, which are making the development of these projects more efficient and, thus, more profitable (Table 1).

Projects of CO2–EOR
The oil revenues produced or reduced total project costs and expand the amount of CO2 stored per unit of investment.	Developing a series of such projects would help reduce CCUS costs more generally and could provide the catalyst for commercial-scale CCUS to eventually take off.

Table 1.

Benefits of lifecycle emissions on CO₂ reduction of CO₂–EOR projects [8].

Guaranteeing the integrity of CO₂ storage is also essential for confirming the emissions decreases. There are some path operators, which demonstrate the permanency of CO₂ storage, admitting sites with appropriate geology that gets CO₂, avoiding abandoned oil wells that could create a passage for CO₂ to get the surface (or checking that these are obstructed), and inserting observance and field surveillance to notice possible escape [8].

An additional potential advantage of CO₂–EOR is that it offers a lower-cost opportunity to position CCUS projects.

4. Enhance the oil recovery process using ccs

From a geological perspective, the traps can be structural and stratigraphic, and the EOR could be from abandoned or deleted reservoirs:

In addition to the information shown in Table 2, there are two types of CO₂–EOR based on the miscibility between CO₂ and the reservoir oil. The pressure at which miscibility occurs is defined as the minimum miscibility pressure (MMP) [9].

Groups of EOR technologies:	Recovery of miscible gases
	Chemical flooding
	Thermal recovery
	Microbial flooding

Table 2.

EOR Technologies [9].

As part of the CO₂ – EOR operation, CO₂ is inserted into a stratum containing oil at high pressure. The displacement of oil by CO₂ injection is founded on the phase behavior of gas–oil mixtures, which are highly interdependent on the temperature, pressure, and constitution of the reservoir oil. Two main types of CO₂–EOR procedures are recognized [1].

The main processes participating in the immiscible CO₂ floods are:

• Increased oil stage, as the oil gets soaked with CO₂.

• Viscosity decreases in the mixture of oil and CO₂.

• Pumping of lighter hydrocarbons in the CO₂ phase. and

• Displacement of liquid by the increase of pressure.

This assemblage of mechanisms allows a part of the left-over oil in the reservoir to be still, moved and extracted (Figure 3).

Figure 3.

Diagram presenting the miscible CO₂–EOR procedure [10].

CO₂ capture has been shown as one of the most successful EOR methods, especially in the United States, because it uses the available CO₂ deposits that are present in nature.

As can be identified in Figure 4, there are two sources of CO₂:

• The gas CO₂ is associated with the gas and oil pumping from which the oil company purifies it and transports it to the CO₂ liquefaction installation using pipelines, which is a free gas source.

• Liquid CO₂ is obtained from a chemical plant not so far from the project that is trucked to the CO₂ storage installation.

Figure 4.

Production flow diagram of the CO₂–EOR project [9].

As for the CO₂ extraction process, the first measure in CCS is to obtain it from other gaseous substances. CO₂ can be seized from natural gas by absorption, adsorption, chemical looping, or membrane gas detachment, or it can be captured from flue gas at big CO₂ location origin (coal power station and industrial processes units) by using one of the following three methods—pre-combustion capture, post-combustion capture, and oxy-combustion. Once obtained, the CO₂ is dehydrated and equipped for transport. It is transported by pipeline, truck, or ship in a supercritical state to the storehouse site, see Figure 4 [5].

5. Possible applications of the method CCUS–EOR IN the EASTERN LLANOS basin (Colombia)

In general, the actual Eastern Llanos basin is a suitable basin for the storage of CO₂–EOR because it meets the criteria mentioned above, such as 1) natural gas and oil production, 2) extensive basin with hydrodynamic traps, and 3) several reservoir formations with good regional confinement. To this is added that oil fields are varied and extensive, and a considerable number of these hydrocarbon exploitation projects are in the maturation stage where it is necessary to increase the production of hydrocarbons through improved recovery and thus prolong their useful life (Figure 5).

Figure 5.

The Eastern Llanos basin located in the bigger Orinoco River basin in northern South America.

“The Eastern Llanos Basin is the most prolific hydrocarbon basin in continental Colombia. The northern boundary of this basin is the Colombian–Venezuelan delimitation; to the south, the basin goes as far as the Macarena high, the Vaupés Arch and the Precambrian metamorphic rocks that outcrops to the south of the Guaviare river; the east limit is marked by the outcrops of Precambrian plutonic rocks of the Guyana Shield, and to the west, the basin is restricted by the frontal thrust system of the Eastern Cordillera” (Figure 5) [11].

A schematic drawing cross section of the Eastern Llanos basin shows that the oil-related formations are of Cretaceous, Paleogene, and Neogene ages, between the Eastern Cordillera westward and the Brazilian craton eastward (Figure 6). The Eastern Llanos is a complete foreland basin that changed when the Andes were pushed to the east against the South American plate. The structural surroundings allow the geological formations in the basin that stayed mostly planar and undisturbed, fashioning them favorable for CO2 sequestration.

Figure 6.

Cross section of the foreland Eastern Llanos basin [11].

Basin development began in the Paleozoic with rifting. Clastic materials were sedimented over the Precambrian basement from the Triassic time to the Late Cretaceous. The basin was the oriental block of a major rift system. From the Maastrichtian to the Paleocene time, the Llanos basin developed into a foreland. During the Neogene, the basin has been a deposit of thickened molasse sediments. The source rocks are Cretaceous, and span from immature to marginally mature eastward of the frontal thrust. The main deposits are clastic units of the Late Cretaceous and Paleogene ages. Investigation of the individual elements of the migration arrangement inside the basin is complex because of the thinning of the stratigraphic segment and the evolution of more sandy facies in the direction of the Guyana Shield [9].

5.1 Petroleum geology

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].

Figure 7.

Petroleum Geology—Eastern Basin [11].

Figure 8.

Eastern Llanos Basin Petroleum system chart [11].

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.