SIMULATION MODEL

A single well simulation model was created based on the main properties from the reservoir candidate to implement the HYB SEN hybrid technology. Figure 1 shows the 3D representation of the radial model used in this research. Additionally, table 1 references the main parameters related to petrophysical properties and grid size of the numerical model.

Figure 1 Numerical simulation model. 

Table 1 Reservoir and grid parameters numerical simulation model. 

To estimate the greenhouse gases for the baseline, the pseudo-aquathermolysis reaction and its kinetic parameters were ncluded, which were determined from experimental tests such as high-pressure thermogravimetric analysis (TGA), reactor tests isoconversional, and gas spectrometry of the reaction products, which were also performed for crude in the presence of the nanocatalysts selected for the hybrid technology called AINiPd.

The kinetic parameters were estimated from the results of the thermogravimetric tests using Friedman's isoconversional method (^{Pretell et al., 2020}) as observed in previous work reported by ^{Ruiz-Cañas et al., 2023}. The catalytic effect of the nanomaterial's presence on the reactions that occur in the test evaluation range (25 -600°C) should be highlighted.

Figure 2 High-pressure TGA for asphaltene in the absence and presence of the core - shell nanoparticles based on alumina (76 nm). 

The presence of nanocatalysts generated a reduction in the activation energy concerning the reaction with asphaltenes alone, which indicates that the selected nanomaterial is indeed able to catalyze the thermal decomposition reaction of asphaltenes and reduce the amount of energy required.

In addition, in the presence of steam, aquathermolysis reactions occur, which mainly form gaseous components such as carbon dioxide, carbon monoxide, and hydrogen sulfide, among others. The reaction that has been modeled by Hyne (^{Hyne, 1986}), shown in Equation 1, stands out.

Equation 1. Hyne's reaction model.

Where GHL represents light gaseous hydrocarbons and, H₂O: water, CO₂: carbon dioxide, CH₄: methane, CO: carbon monoxide, H₂S: hydrogen sulfide and H₂: hydrogen.

To estimate the stoichiometry of the reaction, the results of mass spectrometry of the TGA with steam test of the asphaltene fraction of crude oil in the presence of nanocatalysts were analyzed (Figure 3), and the fractions obtained according to the molecular weight of each compound produced allow to determine the molar composition of the components in the reaction, and thus determine the stoichiometry of the pseudo-aquathermolysis reaction for this case.

Figure 3 Distribution of the selectivity of gases produced by the reaction for asphaltene in the absence and presence of the nanocatalysts. 

There is a signficant decrease in gases such as COx, NOx, and SOx compared to the pseudo-aquathermolysis reaction not involving nanocatalysts. It is worth noting that the Hyne model accounts for H₂S as a by-product of the sulfur compounds in crude oil. However, since the amount of H₂S produced was small and could not be detected in the chromatography, the reaction was normalized to exclude H₂S as a product. Despite this adjustment, the presence of nanocatalysts resulted in a reduction in the composition of SOX and NOX produced. The kinetic parameters for crude oil are shown in Table 2 based on the results obtained.

Table 2 Kinetic parameters for the pseudo-aquathermolysis reaction with asphaltene. 

In addition, the conventional cyclic steam injection reaction model (Equation 2) suggests the generation of light compounds.

Equation 2. Modified pseudo-aquathermolysis reaction model for conventional CSS.

In general, there are three phenomena associated to the HYB -SEN scenario: The first one involves the functionalized metallic nanoparticles that act as a catalyst for the pseudo-aquathermolysis reaction, the second one is the co-dilution effect due to the presence of the carrier solvent (naphtha) in the process, and the third one is the upgrading of crude, which leads to a compositional change of the initial crude oil. To model these phenomena, it was necessary to include activation energy at the temperature at which thermal decomposition occurs.

Table 3 Kinetic parameters for the pseudo-aquathermolysis reaction in the presence of nanocatalysts. 

Next, a chemical reaction (Table 3) is proposed where the original oil of the simulation model reacts with water, generating combustion gases and light hydrocarbons.

Equation 3. Modified pseudo-aquathermolysis reaction model in the presence of nanocatalysts.

The reaction and its kinetics are included in the numerical model. The mass balance error is 10-5, which is accurate for generating the reaction.

The base fluid model has three components: dead oil, gas in solution, and water. Experimental tests carried out on the crude under study allowed the determination of crude oil average molecular weight and density of naphtha, among others. Table 4 shows the physicochemical properties of the components included.

Table 4 Physicochemical properties of the components included in the model. 

EVALUATION OF NANOFLUIDS INJECTION SCENARIOS

To determine the impact on the reduction of greenhouse gases of the hybrid steam technology with naphtha-based nanofluids and the cyclical injection of conventional steam in the evaluation window of 10 years (2020 - 2030), the following scenarios were created:

In general, the injection scheme for the base case of cyclic steam injection is as follows: primary production is carried out for three months in the well; then, steam is injected at a constant rate of 1350 bbl/d for six days, with a steam quality of 60% and an njection temperature of 520°F, followed by three days of soaking and then the well is opened for production until it reaches the primary production rate, at which time a new production cycle is started. It should be noted that the model has an injection pressure restriction of 1500 psi, which Is the maximum pressure allowed to avoid possible fracturing of the reservoir.

On the other hand, the nanofluid batch Injection rate was calculated concerning the estimated daily steam injection rate in the base case, 1350 bbl/day, with a 10% ratio that is, 135 bbl/day. It hould be mentioned that the amount of steam Injected was the same as the base case, 8100 barrels in each cycle, 60% steam quality, pressure, and temperature conditions equal to those of the base case, and the same soaking time. Table 5 shows the injection-production conditions for the hybrid technology.

Table 5 Injection - Production Properties of the model. 

Furthermore, the simulation of nanofluid Injection scenarios Included the keyword "restart" twice: one prior to and the other following its Integration In the second cycle of CCS. The primary Influence is associated with pseudo-aquathermolysis. In the Initial cycle of CCS, a pseudo-aquathermolysis reaction occurs without nanofluid, while in the second cycle, it involves a reaction with nanofluid. Subsequently from the third cycle onward, the pseudo-aquathermolysis reaction without nanofluid is established again (Figure 4).

Figure 4 Simulation Strategy Hybrid Technology and base case of steam injection. 

It should be noted that nanofluid Injection scenarios were created in the second injection cycle as it was the most favorable one for the hybrid CSS + nanofluid technology. In addition, special variables were monitored for analyzing the occurrence of the pseudo-aquathermolysis reaction In the presence of steam and the production of resulting gases.

ENVIRONMENTAL INDICATORS

The proposed environmental Indicators calculations depend on the production of C0₂, which is a function of the origin, and the energy source of the steam generator used for the process. In general, process carbon footprint calculation Is based on ISO 14040 - 44, ISO 14064, and IPCC 2006 standards.

Also, C0₂ capture is mainly performed with amines and can cost approximately USD 115/ton C0₂, (Dzlejarski et al., 2023), which could affect the economics of recovery projects. In addition, steam Injection processes generate a signficant amount of C0₂; It Is in the order of 100 kg of C0₂/bbl, in contrast to methods such as polymer Injection which generate less than 12 kg of C0₂/bbl of oil, (^{Farajzadeh et al. 2022}) mainly due to the combustion produced in steam generators. Therefore, and based on the analysis of the process, the following environmental Indicators are proposed:

EVALUATION OF THE PSEUDO-AQUATERMOLYSIS REACTION IN STEAM INJECTION PROCESSES

Figure 5 shows the oil production results and daily oil production rates for the CSS baseline, CSS + Solvent and CSS + Hyb-SEN technology.

Figure 5 Cumulative oil and oil production rate, Hybrid Technology nanocatalyst, base case of steam injection and solvent (2020 - 2030). 

The incremental recovery obtained by hybrid CSS + Hyb-SEN technology implementation in the evaluation period (2020 to 2030) is 3756.46 bbl compared to the conventional CSS base (Figure 6).

Figure 6 Cumulative oil and oil production rate, Hybrid Technology nanocatalysts, base case of steam injection and solvent (2020 - 2030). 

Analyzing the 2020 to 2024 period, which includes the second cycle where the hybrid CSS + Hyb-SEN technology is applied, the incremental oil recovery compared to the CCS base case is 8256.72 bbl (Figure 7). It is worth noting that the CSS + solvent has a very low cumulative oil increment (236 bbl), which is not evident in the figure.

Figure 7 Cumulative oil - 2_nd cycle, Hybrid Technology nanocatalysts, base case of steam injection and solvent (2022 - 2024). 

The CSS + Hyb-SEN technology showed the most favorable outcomes, indicating its potential as a highly effective enhanced oil recovery (EOR) technique. This method showed significant improvement in oil recovery rates. However, in the CSS + solvent case, the results were comparable to the baseline CSS case, suggesting that adding solvent without nanocatalysts did not significantly enhance the overall recovery performance. The reduction in viscosity due to the solvent is the only effect related to this process, in contrast to the hybrid nanocatalyst technology that involves additional mechanisms as catalysts of the reaction.

Likewise, each of the gases produced by the pseudo-aquathermolysis reaction for the base case and the implementation of hybrid technology is analyzed. Figure 8 shows CO₂ production.

Figure 8 CO₂ production, Hyb-SEN for CSS and baseline. 

The CO₂ generated in the hybrid technology is considerably less than that obtained in the base case by amounts of 311.92 and 383.11 lb mol, respectively. Also, for the second cycle, the CO₂ generated for the CSS + nanofluid was 238.09 lb mol, while for CSS, it was 281.96 lb mol. The latter indicates that the implementation of hybrid technology reduces the production of CO₂ released into the atmosphere due to the nanofluid effect until the sixth cycle.

Figure 9 shows the estimation of CO production for the hybrid technology of CSS + naphtha-based nanofluids and the base case.

Figure 9 CO production, Hyb-SEN for CSS, and baseline. 

The production of CO obtained by the implementation of the Hyb-SEN for CSS is lower by 52.50 lb mol compared to conventional CSS, which in turn is equivalent to a reduction of approximately 3.95% due to the catalysis of the pseudo-aquathermolysis reaction as evidenced in the experimental tests carried out on the crude in the presence and absence of nanomaterials. For the second cycle, the reduction was 13.9%, with a CO reduction of 144.70 lb mol with respect to CSS.

On the other hand, the summary of the greenhouse gases produced by hybrid technology and the conventional cyclical steam injection is shown in Table 6. The results show a reduction in gases compared to the base case (greater than 18% for the CO₂ production); this indicates that hybrid technology positively impacts on reducing the carbon footprint.

Table 6 Summary of greenhouse (COx) gas production for the evaluated scenarios. 

Additionally, the production of light hydrocarbon gases was estimated for both cases. The results are shown in Figure 10.

Figure 10 Light gases production for hybrid technology and conventional CSS. 

The light gases produced by conventional CSS + Solvent nanofluid are considerably higher than those obtained with CSS base. Table 7 shows the summary of gas production.

Table 7 Summary of production of hydrocarbon gases for the evaluated scenarios 

Low molecular weight hydrocarbon gases (methane, C₂H₆, C₃H₈) could be a source of energy, that is, as a replacement for natural gas in processes used in the plant, such as steam generation for reducing the effect of greenhouse gases. Since low molecular gases are released directly into the atmosphere, they can be 25 times more polluting than CO₂.

Additionally, Figure 11 shows the cumulative SOR and the water cut instantaneity of the two evaluated scenarios. As observed with the hybrid technology, there is a significant reduction of cumulative SOR, which means that the nanoparticles contribute to incremental oil production with the same injected steam compared to the CSS base scenario. However, the BSW instantaneity compared to the base case increased due to the change in the fluids' movement and the catalytic effect of nanoparticles in the second cycle and the permeability relative curves.

Figure 11 SOR and water cut for the base case and hybrid technology. 

According to the results obtained in this stage, it is concluded that there is a high reduction of COx gases with the use of nanocatalysts, also generating an increase in oil production, achieving a more energy-efficient process with this hybrid technology.

ENVIRONMENTAL IMPACT CALCULATION

Following the proposed environmental indicators and methodology reported by ^{Osma et al., 2019}, the environmental impact calculation was performed for the hybrid technology scenario and baseline. The carbon intensity index results were obtained at this stage considering the CO₂ production from steam generation supported by the UPME emissions calculation tool for the scenario evaluated Hyb-SEN, with a steam rate equal to the baseline considering the CO₂ generated in the reservoir and due to steam generation. Table 8 shows the results for the CSS baseline and Hyb-SEN for CSS.

Table 8 Environmental indicators for the base case and hybrid technology. 

Improvements on environmental indicators are obtained for hybrid technology concerning conventional steam technology, reflected in a lower carbon-intensity index and reduction of SOR, which indicates better energy efficiency requiring less steam per barrel of oil produced and a lower water cut.

Likewise, as a complement to the environmental impact analysis, Figure 12 shows the flow diagram of the relevant unit operations that occurred in a conventional cyclical steam injection process.

Figure 12 Analysis of operations carried out in the cyclical injection of steam. 

In contrast, Figure 13 shows the process diagram for hybrid technology that presents an additional benefit from the use of naphtha-based nanofluids in the use of raw materials in situ with the technology used for crude oil transportation. The latter could imply a subsequent reduction in their use, considering the current naphtha requirements in the conventional process and comparing it with that of hybrid technology.

Figure 13 Analysis of operations carried out in hybrid technology.