**2. Carbon capture**

Carbon capture technology started in the 1970s in North America at industrial projects before it was applied to power generation [1]. Early application of carbon capture on a commercial basis was focused on the removal of CO2 as part of certain industrial processes in concentrated streams [1, 8]. The Department of Energy (DOE) estimates that approximately 30 million metric tons per year of pure CO2 are currently produced at industrial facilities located within 50 miles of existing CO2 pipeline networks [10].

Some industrial processes with large-scale carbon capture in commercial operation include coal gasification, ethanol production, fertilizer production, natural gas processing, refinery hydrogen production, and coal-fired power generation [7, 10].


However, with the recent inclusion of power generation, new systems are designed to capture and concentrate CO2 using the following processes [7]:

• Pre-combustion carbon capture

and storage in the U.S. is approximately 30 billion metric tons, equivalent to 35 years of CO<sup>2</sup>

sequestration.

nically feasible. Different forms of trapping mechanisms, such as hydrodynamic and capillary

and high permeability) in the Permian Basin, located in West Texas and southeastern New Mexico [4]. Approximately 11 trillion cubic feet (560 million metric tons) total volume of CO<sup>2</sup>

emissions from industrial sources [1, 4–6].

effective, the potential to sequester in unconventional organic-rich shales (gas/oil) is even more promising and economical, yet there has been minimum attention given to these vast

adsorptive surface of kerogen and kerogen nanopores in shales can store substantial amounts

Carbon capture technology started in the 1970s in North America at industrial projects before it was applied to power generation [1]. Early application of carbon capture on a commercial

streams [1, 8]. The Department of Energy (DOE) estimates that approximately 30 million met-

Some industrial processes with large-scale carbon capture in commercial operation include coal gasification, ethanol production, fertilizer production, natural gas processing, refinery

in its adsorbed state [5–7]. Thus, in depleted shale gas reservoirs, injected CO2

, indicating trapping or storage. Hence, incorporating the storage of anthropogenic



) in the kerogen micro and nanopores and adsorb to the kerogen surface for

in place to prevent movement/leakage, ubiquitous to almost all oil and



as part of certain industrial processes in concentrated

are currently produced at industrial facilities located within

emissions are usually injected into geologic formations such as deep saline


into an oil/gas reservoir to recover more hydrocarbons

differs from that of the produced fluid


storage due to the ultra-tight

leakage. Moreover, the

sequestration in kero-

replaces


emissions captured from 140 Gigawatts (GWs) of coal-fired power [2, 3].

aquifers for storage, but most recently associated with enhanced oil recovery (CO2

The captured CO2

CO2

CO2

with CO2

into CO2

trapping hold the CO2

is utilized in by US CO2

per year of total US CO2

gas reservoirs [2, 3].

volume of CO2

Although, CO<sup>2</sup>

of CO2

methane (CH4

gen nanopores.

**2. Carbon capture**

basis was focused on the removal of CO2

ric tons per year of pure CO2

50 miles of existing CO2

and gas reservoirs. Although, CO<sup>2</sup>

58 Carbon Capture, Utilization and Sequestration

combine the recovery process with CO2


(oil and/ or gas). Mostly, the volume of the injected CO2

storage during CO2

resources. Organic-rich shales are naturally suited for CO2

impermeable nature of the formation, which would curtail CO2

storage [7–9]. This chapter therefore investigates the potential of CO2

pipeline networks [10].

hydrogen production, and coal-fired power generation [7, 10].

The United States (US) leads the world in both the number of CO2

Fuel undergoes gasification instead of combustion to produce syngas made of carbon monoxide (CO) and hydrogen (H2 ). Carbon monoxide (CO) is then converted to CO2 through a later shift reaction, while a solvent separates the CO2 from H2 . The pre-combustion carbon capture is mostly combined with an integrated gasification combined cycle (IGCC) power plant to burn the H2 in a combustion turbine and the resulting exhaust heat, used to power a steam turbine [1, 6].

• Post-combustion carbon capture

It involves the use of chemical solvents to separate CO2 from the resulting flue gas from fossil fuel combustion. This method is commonly used by modified power plants for carbon capture [7].

• Oxyfuel carbon capture

This process requires the combustion of fossil fuel in pure oxygen to render the CO2 -rich exhaust gas for capture [7].

In 2016, the US Energy Information Administration (EIA) reported that electricity generated from natural gas is expected to exceed that of coal for the first time [9]. This calls for more effective measures to be put in place to curtail greenhouse gas (GHG) effects.

#### **2.1. Carbon capture benchmarks**

There are about 21 commercial-scale carbon capture projects around the world with 22 more in development [7]. Below is a list of a few of the many benchmarks in carbon capture:

• As of 2017, the Archer Daniels Midland (ADM) Company captures CO<sup>2</sup> from Biofuels (ethanol) production, and stores in the Mt. Simon Sandstone, a deep saline formation, Decatur, IL. An estimated amount of 1.1 million tons of CO<sup>2</sup> is captured per year [1, 3].

• In 2017, the NRG Petra Nova Project, TX, captures 90% of CO<sup>2</sup> (approximately, 1.6 million tons of CO2 per year) from a 240 MW slipstream of flue gas of existing WA Parish plant, and transported to a nearby oil field [7].

trapped, hence the need for CO2

miscibility pressure (MMP), CO2

in its gaseous or supercritical state. The injected CO2

sweep of the reservoir [13, 14]. Miscibility of CO2

either carbonates or sandstone could be suitable for CO2

provides a market and revenues for the captured CO2

through a capillary trapping mechanism [10, 13, 14].

while recycled volumes increase. This indicates that CO2

. In so doing, subsequent projects employ CO2

southeastern New Mexico. These initial projects used separated CO<sup>2</sup>

Colorado [10]. The recent depletion of the natural source fields of CO<sup>2</sup>

OOIP [4, 9, 10].

dioxide (CO2

CO2

ing CO2

CO2

CO2

CO2

reached [13, 14].

The operation of a CO2

half of the injected CO2

increase in trapped CO2

gas and natural sources of CO2

The produced CO2

**Figure 2** shows CO2

of the pipelines for CO2

supply large quantities of CO2

improves the flooding efficiency [10, 13–15].

where fluids (CO<sup>2</sup>


Carbon Dioxide Utilization and Sequestration in Kerogen Nanopores

is injected either

61

is determined to reduce the interfacial

http://dx.doi.org/10.5772/intechopen.78235

with the oil is important as it causes the



diminishes,


from anthropogenic (industrial and

is being stored in the formation

from processed natural

and size limitation

from industrial power plants.

molecules from captured emissions to

and oil will no longer be miscible, the oil and gas phases


is trapped or dissolved in the reservoir and its fluids (oil and water).

with oil is separated and re-injected back into the reservoir, ensuring an

instead of being released to the atmosphere. In addition, CO2



for EOR processes in oil fields. Technological advancement in

, nitrogen, enriched gas, polymer solutions or surfactant solutions) are

flooding. Both primary and secondary recovery methods usually extract about 35% of the

To produce more of the remaining oil-in-place, a tertiary oil recovery phase is implemented,

injected to interact with the oil and cause substantial changes to the oil properties [12]. Carbon

tension, minimize the viscosity of the oil to make it lighter, cause the oil volume to swell, and eventually cause the oil to flow more freely within the reservoir to the producer wellbore [11].

physical forces (interfacial tension) holding the two phases apart to disappear. It occurs at a minimum pressure (MMP), where about 95% of the OOIP is recovered. Below the minimum

separate, thereby decreasing oil production rate. Significant volumes of oil are produced dur-

than 120 million incremental barrels of oil through 2008, with more than 2 billion barrels of OOIP and 40% of oil remaining after Waterflooding [14, 15, 19]. All types of oil reservoirs,


instead of anthropogenic CO2

to present day [9, 16]. Three developed source fields include, Sheep Mountain in south central Colorado, Bravo Dome in northeastern New Mexico, and McElmo Dome in southwestern



power plants) sources [14, 15]. As the project matures, the volume of injected CO<sup>2</sup>

 is mostly delivered to the field at a high pressure (>1200 psi) and density (5 lb. /gal) into injection wells within a designed pattern based on computer simulation to optimize areal

) flooding is one of the most proven EOR methods, where CO<sup>2</sup>


#### **3. Carbon dioxide utilization (CO2 : EOR)**

CO2 -EOR has been successfully implemented for nearly half a century now to recover additional oil from developed conventional oil fields in the United States and around the world. It involves the injection of CO2 , either in its supercritical or gaseous state to re-pressurize a depleted reservoir pressure to cause residual oil held in the smaller pores by capillary forces to be released [9, 10]. CO2 , unlike other fluids, reaches miscibility with crude oil at lower pressures. Furthermore, it is less expensive than other miscible fluids. As such the injected CO2 becomes soluble with the residual oil as light hydrocarbons from the oil dissolve in the CO2 while the CO2 density is high when oil contains a significant volume of light hydrocarbons [4, 11].

Upon discovery, an oil reservoir is initially produced by means of the pressure gradients within the reservoir that provides the energy to move reservoir fluids to the surface. This is called the primary production stage. Eventually, the reservoir pressure declines and flow to the wellbore ceases. At this moment, a range of secondary or tertiary (EOR) methods are implemented to recover additional volumes of oil. The primary stage only recovers about 5–20% of the original oil-in-place (OOIP), with considerable amount of oil left trapped in the pore spaces of the rock [9, 12].

The next stage of production is the secondary recovery, which involves the injection of a fluid, either gas or water to sustain and maintain the depleted reservoir drive, and simultaneously recover substantial amounts of the remaining OOIP. Treated produced water (waterflooding) is commonly used at this stage since it is less expensive and readily available. In most cases, the water bypasses the oil due to difference in viscosity leaving behind significant amounts of the remaining oil-in-place. Waterflooding results in approximately 50–60% of the OOIP trapped, hence the need for CO2 -EOR in most oil reservoirs already replenished with waterflooding. Both primary and secondary recovery methods usually extract about 35% of the OOIP [4, 9, 10].

• In 2017, the NRG Petra Nova Project, TX, captures 90% of CO<sup>2</sup>

per year) from a 240 MW slipstream of flue gas of existing WA Parish plant, and

annually from hydrogen production units and injects it into a deep saline

for enhanced oil recovery by the Abu Dhabi National Oil

stream for utilization in the Permian Basin, among

, either in its supercritical or gaseous state to re-pressurize a

, unlike other fluids, reaches miscibility with crude oil at lower

density is high when oil contains a significant volume of light hydrocar-

• In 2016, Abu Dhabi CCS Project Phase 1: Emirates Steel Industries, an operating iron and

• In 2015, Shell Quest Project, AB, CA, a bitumen upgrader complex, captures about 1 mil-

• In 2013, Conestoga Energy Partners/Petro-Santander Bonanza Bioethanol plant, KS, an eth-

• In 2010, Occidental Petroleum's Century Plant (OPCP), TX, a natural gas processing facil-

**: EOR)**


depleted reservoir pressure to cause residual oil held in the smaller pores by capillary forces

pressures. Furthermore, it is less expensive than other miscible fluids. As such the injected

Upon discovery, an oil reservoir is initially produced by means of the pressure gradients within the reservoir that provides the energy to move reservoir fluids to the surface. This is called the primary production stage. Eventually, the reservoir pressure declines and flow to the wellbore ceases. At this moment, a range of secondary or tertiary (EOR) methods are implemented to recover additional volumes of oil. The primary stage only recovers about 5–20% of the original oil-in-place (OOIP), with considerable amount of oil left trapped in the

The next stage of production is the secondary recovery, which involves the injection of a fluid, either gas or water to sustain and maintain the depleted reservoir drive, and simultaneously recover substantial amounts of the remaining OOIP. Treated produced water (waterflooding) is commonly used at this stage since it is less expensive and readily available. In most cases, the water bypasses the oil due to difference in viscosity leaving behind significant amounts of the remaining oil-in-place. Waterflooding results in approximately 50–60% of the OOIP

becomes soluble with the residual oil as light hydrocarbons from the oil dissolve in the

anol plant, captures and supplies approximately 100,000 tons of CO2

tons of CO2

lion tons of CO2

EOR field [1, 5].

others [3, 5].

CO2

CO2

CO2

bons [4, 11].

transported to a nearby oil field [7].

steel plant, used to capture CO2

formation for sequestration [7].

ity, compresses and transports CO2

**3. Carbon dioxide utilization (CO2**

It involves the injection of CO2

to be released [9, 10]. CO2

pore spaces of the rock [9, 12].

while the CO2

Company (ADNOC) [3, 5].

60 Carbon Capture, Utilization and Sequestration

(approximately, 1.6 million

per year to a Kansas

To produce more of the remaining oil-in-place, a tertiary oil recovery phase is implemented, where fluids (CO<sup>2</sup> , nitrogen, enriched gas, polymer solutions or surfactant solutions) are injected to interact with the oil and cause substantial changes to the oil properties [12]. Carbon dioxide (CO2 ) flooding is one of the most proven EOR methods, where CO<sup>2</sup> is injected either in its gaseous or supercritical state. The injected CO2 is determined to reduce the interfacial tension, minimize the viscosity of the oil to make it lighter, cause the oil volume to swell, and eventually cause the oil to flow more freely within the reservoir to the producer wellbore [11].

CO2 is mostly delivered to the field at a high pressure (>1200 psi) and density (5 lb. /gal) into injection wells within a designed pattern based on computer simulation to optimize areal sweep of the reservoir [13, 14]. Miscibility of CO2 with the oil is important as it causes the physical forces (interfacial tension) holding the two phases apart to disappear. It occurs at a minimum pressure (MMP), where about 95% of the OOIP is recovered. Below the minimum miscibility pressure (MMP), CO2 and oil will no longer be miscible, the oil and gas phases separate, thereby decreasing oil production rate. Significant volumes of oil are produced during CO2 -EOR. For example, the Wasson field, a Denver unit CO<sup>2</sup> -EOR has produced more than 120 million incremental barrels of oil through 2008, with more than 2 billion barrels of OOIP and 40% of oil remaining after Waterflooding [14, 15, 19]. All types of oil reservoirs, either carbonates or sandstone could be suitable for CO2 -EOR provided the MMP can be reached [13, 14].

The operation of a CO2 -EOR project is a closed-loop system as shown in **Figure 1**, where about half of the injected CO2 is trapped or dissolved in the reservoir and its fluids (oil and water). The produced CO2 with oil is separated and re-injected back into the reservoir, ensuring an increase in trapped CO2 instead of being released to the atmosphere. In addition, CO2 -EOR provides a market and revenues for the captured CO2 from anthropogenic (industrial and power plants) sources [14, 15]. As the project matures, the volume of injected CO<sup>2</sup> diminishes, while recycled volumes increase. This indicates that CO2 is being stored in the formation through a capillary trapping mechanism [10, 13, 14].

CO2 -EOR was first tested on a large-scale in the 1970s in the Permian Basin of West Texas and southeastern New Mexico. These initial projects used separated CO<sup>2</sup> from processed natural gas and natural sources of CO2 instead of anthropogenic CO2 from industrial power plants. **Figure 2** shows CO2 -EOR projects carried out around the world and in the U.S. from the 1970s to present day [9, 16]. Three developed source fields include, Sheep Mountain in south central Colorado, Bravo Dome in northeastern New Mexico, and McElmo Dome in southwestern Colorado [10]. The recent depletion of the natural source fields of CO<sup>2</sup> and size limitation of the pipelines for CO2 -EOR processes have paved the way for anthropogenic supplies of CO2 . In so doing, subsequent projects employ CO2 molecules from captured emissions to supply large quantities of CO2 for EOR processes in oil fields. Technological advancement in CO2 -EOR applications, such as 3D seismic and geomodeling reduce the rise of failures and improves the flooding efficiency [10, 13–15].

**4. Carbon dioxide sequestration**

until extracted [1, 4, 6, 16]. In so doing, CO2

the purchased volume and is given as [10].

produced, and *CO*2*purchased* is the purchased CO2

power outages, among others [10].

tually converts the injected CO2

encountered in the case of CO2

• Solubility trapping

CO2

is injected. Percentage of stored CO2

injected and CO2

**4.1. Storage mechanisms in conventional reservoirs**

Trapping mechanisms encountered in CO2

sequestration in geologic formations is possible from the fact that cer-

from power plants and industrial facilities can

Carbon Dioxide Utilization and Sequestration in Kerogen Nanopores

http://dx.doi.org/10.5772/intechopen.78235

63

is based on total injected volumes and not on

produced. Losses may be due to leakages, infrequent


injected, *CO*2*produced* is the CO2

with a higher

plume rises due to

can be safely stored in a


losses is estimated as the difference

tain reservoirs naturally trap and store oil and natural gas over long geological time periods

be trapped and stored in potential geologic formations. A large percentage of the originally

solved in the oil and also end up trapped [3, 6, 17]. These trapping processes continue as long

*CO*2*storage*(%) <sup>=</sup> (*CO*2*injected* <sup>−</sup> *CO*2*produced* <sup>−</sup> *CO*2*losses*)/*CO*2*purchased* (1)

injected. CO2

 can be injected into conventional geological formations and stored deep underground. Most of these conventional geologic formations are at depths greater than 800 m, which even-

[4, 7]. For an effective conventional geological storage, approximately 90–95% of the

density than its gaseous state results in a given volume of rock capable of holding more mass

This involves the migration of generated hydrocarbons from organic matter (source) over long geological periods from the source rock to porous and permeable reservoir rock initially saturated with brine. The accumulated hydrocarbons are trapped below a non-permeable cap rock to prevent further migrations, and the density difference between the fluids separates the fluids into layers with gas on top, followed by oil and brine at the bottom. A similar mechanism is

buoyancy forces and is prevented from escaping by overlying low permeability cap rock [15]. This mechanism is considered to be relatively fast but requires characterization of the cap rock [2, 3].

storage, where the less dense supercritical CO2

for will be sequestered within the reservoir [4, 9, 16].

• Physical trapping: hydrodynamic, stratigraphic, or structural) trapping

is widely accepted to be soluble in water, as such, dissolved CO2

geologic formation under solubility trapping. Since the CO2

into its supercritical state. The supercritical CO2

storage in metric, *CO*2*injected* is the total CO2

gets trapped in the pores of the geologic formation, while a portion of it is dis-

The potential of CO2

where, *CO*2*storage* is the CO2

between total CO2

CO2

of CO2

injected CO2

include [9–11]:

injected CO2

as the CO2

**Figure 1.** Schematic diagram of a closed loop CO2 -EOR [4].

**Figure 2.** CO2 -EOR projects conducted worldwide and in the U.S [10].
