Methane Injection Research Articles

Phase Behavior and Rational Development Mode of a Fractured Gas Condensate Reservoir with High Pressure and Temperature: A Case Study of the Bozi 3 Block

The Bozi 3 reservoir is an ultra-deep condensate reservoir (−7800 m) with a high temperature (138.24 °C) and high pressure (104.78 MPa), leading to complex phase behaviors. Few PVT studies could be referred in the literature to meet such high temperature and pressure conditions. Furthermore, it is questionable regarding the applicability of existing condensate production techniques to such a high temperature and pressure reservoir. This study first characterized the phase behavior via PVT experiments and EOS tuning. The operating conditions were then optimized through reservoir numerical simulation. Results showed that: (1) the critical condensate temperature and pressure of Bozi 3 condensate gas were 326.24 °C and 43.83 MPa, respectively; (2) four gases (methane, recycled dry gas, carbon dioxide, and nitrogen) were analyzed, and methane was identified as the optimal injection gas; (3) gas injection started when the production began to fall and achieved higher recovery than gas injection started when the pressure fell below the dew-point pressure; (4) simultaneous injection of methane at both the upper and lower parts of the reservoir can effectively produce condensate oil over the entire block. This scheme achieved 8690.43 m3 more oil production and 2.75% higher recovery factor in comparison with depletion production.

Experimental and numerical studies of NO reduction by ammonia in different methane flame positions

Blending ammonia with methane for combustion can reduce carbon emissions and improve the flame characteristics of ammonia combustion. However, blending ammonia with methane can easily lead to high concentrations of NOx emissions. This study investigates the impact of different ammonia and methane blending methods on the flame structure and NOx emission by experiments and CFD numerical simulation. The results indicate that simultaneous injection of ammonia and methane through the central fuel tube significantly alters the combustion flame structure and leads to high concentrations of NOx emission. As the ammonia ratio increases, the flame structure transitions from a bright flame to a layered flame with an inner yellow conical small flame surrounded by a light-colored outer flame. When the ammonia ration increases from 0 % to 20 %, NOx emission increase from 15 ppm to 323 ppm, nearly 22 times higher. When ammonia is injected into the methane flame from flame side, the flame above the injection position appears as an orange flame, and a significant reduction in NOx emission is obtained. When the ammonia ratio is 20 % and injected at heights of 20 mm 40 mm, and 60 mm above the fuel exit, the outlet NOx concentrations are 183 ppm, 140 ppm, and 153 ppm respectively, this represents reductions of 43.3 %, 56.6 %, and 52.6 %, respectively. The numerical simulation results indicate that the injection of ammonia leads to the formation of higher concentrations of NH2 and super-vapor H2O, resulting in an orange color flame. The gas temperature and oxygen concentration play a crucial role in NOx emissions. NOx emission is lowest when ammonia is injected into the higher temperature, lower oxygen environment at 40 mm.

Retrofit of a Marine Engine to Dual-Fuel Methane–Diesel: Experimental Analysis of Performance and Exhaust Emission with Continuous and Phased Methane Injection Systems

Shipping is a highly energy-intensive sector, and fleet decarbonization initiatives can significantly reduce greenhouse gas emissions. In the short-to-medium term, internal combustion engines will continue to be used for propulsion or as electricity generators onboard ships. Natural gas is an effective solution which can be used to mitigate greenhouse gas emissions from the marine sector. Considered to be a transitional fuel, it can provide a potential reduction in CO2 emissions of around 20–30%, compared with conventional marine fuels. This work investigated the influence of diesel-injection strategies on the performance and emissions of a single-cylinder prototype compression-ignition engine for marine applications, retrofitted to run as a Low-Pressure Dual-Fuel Engine using natural gas. Two different injection systems were used: a mass flow controller enabling continuous-mode gas feeding, and a Solenoid-Operated Gas Admission Valve for marine applications, the latter allowing phased natural-gas injection. Experimental tests were focused on partial-load conditions, which are critical for dual-fuel engines, with a natural gas/diesel mass ratio of 4:1. Phased injection resulted in reductions in fuel consumption, compared to continuous mode, of up to 11%. Further experiments demonstrated reductions in fuel consumption of up to 20.7% (in equivalent diesel); on the other hand, the unburned hydrocarbon emissions which resulted were an order of magnitude larger than the reference values for full diesel, reducing the benefits in terms of greenhouse gas emissions, with a reduction in Global Warming Potential of only 3% compared to full diesel.

Optimal planning of integrated electricity-natural gas distribution systems with hydrogen enriched compressed natural gas operation

In future integrated electricity-natural gas distribution systems (IEGDS), hydrogen and methane converted from excessive renewable generation will be mixed with natural gas to form hydrogen enriched compressed natural gas (HCNG) for fewer carbon emissions. Consequently, optimal planning of the HCNG-integrated IEGDS plays an essential role in increasing the economy and technical benefits. However, integrating HCNG operation into the planning of IEGDS still has many challenges, such as unrealistic modeling, nonlinear constraints, and the potential risk of voltage violations. The purpose of this paper is to develop a tractable optimization model for planning and operation of the HCNG-integrated IEGDS, aiming to minimize the investment and operating cost, reduce the voltage violation, and improve the renewable power penetration rate. To achieve this, a bilevel optimization model is developed for optimal planning of wind turbines and soft open points (SOPs) in the IEGDS considering comprehensive HCNG operation, in which both hydrogen and methane injection are considered and optimized for different system operation scenarios. Furthermore, the proposed nonlinear model is reformulated to a tractable bilevel mixed-integer second-order cone model using several reformulation techniques and solved by the reformulation and decomposition algorithm. Case studies, performed using the publicly available datasets, are conducted to demonstrate the economic and technical improvement by implementing the proposed planning model. The annual planning results show that incorporating the coordination between SOPs and methane injection results in a 6.77% reduction in investment cost, a 22.64% reduction in operating cost, a 62.69% decrease in voltage violation, and a 23.58% increase in the wind power penetration rate. Moreover, SOPs are more applicable to the safe operation of the IEGDS under high energy load conditions.

Numerical simulation of the Co-combustion of coke and biochar coupled with methane injection in iron ore sintering processes

It is of great significance for cleaner production to partially replace traditional coke with biomass fuel in iron ore sintering processes. However, the higher reactivity of biomass leads to an unacceptable deterioration in sintering performance, which limits its high proportion application. This paper presents the numerical simulation of the technology of combining gaseous fuels and biomass for iron ore sintering. The improvement effect and mechanism of the methane injection method on the heat pattern and performance of the coke/biochar co-sintering bed were discussed. To more accurately quantify the coupling phenomena involved, the proposed model especially considers sub-processes of biomass combustion and gaseous reactions including volatile release/char formation, burning of the volatiles, and the oxidation and gasification of char particles. The results indicated that the equivalent methane heat injection method reached its limit of improvement at a concentration of about 0.6%, and failed to obtain qualified products. The thermal indicators and yield kept increasing within the concentration simulation range of 0∼0.8% under the extra methane method. At a concentration of 0.8%, peak temperature (PT), duration time (DTMZ), and enclosed area (MQI) in the high-temperature zone are 1442.094 K, 165.6 s, and 15923.72 K s, respectively, reaching the level of all coke method. The use of local concentration segregation can significantly optimize heat distribution and increase the yield of the coke/biochar co-sintering process.

Investigation on the edge cooling threshold of the density limit in the J-TEXT tokamak with limiter and divertor configurations

Cooling of the plasma edge is widely considered to be a key element in the density limit (DL) of tokamaks. This paper investigates the critical edge cooling threshold of the DL by exploring various plasma configurations in the joint-Texas experimental tokamak. Notably, significant differences in the edge electron temperature in the vicinity of the last closed flux surface were observed between the limiter and divertor configurations. However, the electron temperature drops to a similar level in the vicinity of q= 3 surface close to DL, independent of the magnetic field configuration. In addition, to evaluate the reliability of the critical edge cooling threshold, experiments were conducted by increasing the carbon impurity content to enhance the edge cooling rate. These experiments involved two approaches to increase the carbon impurity content: methane injection and penetration of a graphite solid source. Results from these experiments indicate that the temperature threshold of the q = 3 surfaces remains consistent even with a stronger edge cooling rate. The consistency observed in the electron temperature threshold near the q = 3 surface, regardless of magnetic configuration or edge cooling rate, could help refine existing theoretical and simulation works and improve the prediction accuracy of the DL disruption.

Molecular dynamics simulation of surfactant reducing MMP between CH4 and n-decane

Reinjecting produced methane offers cost-efficiency and environmental benefits for enhances oil recovery. High minimum miscibility pressure (MMP) in methane-oil systems poses a challenge. To overcome this, researchers are increasingly focusing on using surfactants to reduce MMP, thus enhancing the effectiveness of methane injections for oil recovery. This study investigated the impact of pressure and temperature on the equilibrium interfacial tension of the CH4+n-decane system using molecular dynamics simulations and the vanishing interfacial tension technique. The primary goal was to assess the potential of surfactants in lowering MMP. Among four tested surfactants, ME-6 exhibited the most promise by reducing MMP by 14.10% at 373 K. Key findings include that the addition of ME-6 enriching CH4 at the interface, enhancing its solubility in n-decane, improving n-decane diffusion capacity, CH4 weakens n-decane interactions and strengthens its own interaction with n-decane. As the difference in interactions of n-decane with ME-6's ends decreases, the system trends towards a mixed phase. This research sets the stage for broader applications of mixed-phase methane injection in reservoirs, with the potential for reduced gas flaring and environmental benefits.

Development of Monte Carlo neutral transport code and the application to methane seeding plasma detachment

AbstractThe collisions between neutral particles and plasma in the divertor region determine divertor detachment and heat flux to the target. However, the diagnostic of neutral particle information in the tokamak experiment is very lacking. To study the behavior of neutral particles in the boundary region flexibly and comprehensively, a two‐dimensional kinetic neutral transport code based on Monte Carlo method is developed in this work. The code is applied to simulate the neutral particles in the boundary of EAST device. Firstly, the simulation results are compared with EIRENE using an identical plasma background, and good agreement is obtained. Secondly, the transport of methane and the corresponding hydrocarbon compounds is simulated using the developed code. The methane injection case is compared with the injection of carbon and deuterium molecule mixture gas (ratio 1:2) to investigate their impact on detachment and fueling. The simulation reveals that, compared to the direct carbon atom injection case, charge‐exchange collision is the dominant collision of neutral methane (hydrocarbons), which suppresses divertor power radiation and plasma detachment while promoting the improvement of fueling efficiency.

Effect of methane injection strategy on combustion, exergetic performance, and enviro-economic analyses in a diesel/methane CRDI engine

To assess the applicability of methane gas in the context of a methane injection strategy in dual fuel concept, it is crucial to evaluate not only the engine performance but also the exergetic performance and the enviro-economic analyses. In this experimental study, a comprehensive investigation was performed to explore the impacts of a methane injection strategy, involving the timing and quantity of methane gas injection, on the combustion and emission characteristics of a diesel/methane dual-fuel operation. Also, an assessment of energy, exergy, environmental impact, and cost analyses on methane injection strategy using data obtained from experimental results was performed. In the literature, there is a deficiency regarding the evaluation of methane injection strategy in terms of energy, exergy, and enviro-economic analyses. This study will not only address the current research gaps but also serve as a reference for future investigations. The experiments were conducted on a single-cylinder, air-cooled, diesel engine with a common rail fuel system, operating at a fixed engine speed and load. In the experiments, methane injection timing (MIT) was advanced from 20 CAD aTDC to 60 CAD aTDC in 10 CAD increments. The methane injection duration (MID) was increased from 2 ms to 4 ms in 0.5 ms increments. The results have demonstrated that delaying the MIT increases combustion stability compared to early MIT and shortens ignition delay time. High HC and CO emissions resulting from early MIT have been reduced by up to 26 % and 19 %, respectively, with the delay of MIT. Through the delayed MIT application, the diesel/methane study yielded higher exergetic efficiency, lower exergy destruction, and entropy generation compared to the only-diesel operation. Additionally, lower environmental impact and cost values were obtained due to combustion at lower temperatures compared to diesel.

Comparing the properties and growth of graphene on electrolytic and rolled Cu foils by chemical vapor deposition

In this work, we use electrolytic copper foils as substrates for the deposition of graphene by chemical vapor deposition. We investigate the effects of preannealing conditions, methane injection time, and temperature to synthesize graphene with a similar quality as when grown on cold-rolled copper. We find that the electrolytic copper foil’s annealing conditions and CH4 injection temperature determine the quality of graphene.

Efficiency and power enhancement strategies for methane direct injection argon power cycle engines

Argon Power Cycle (APC) is a novel concept for high efficiency and zero carbon emissions, which replaces the air by an argon-oxygen mixture. Previous studies have experimentally demonstrated that APC has a great efficiency enhancement potential for methane-fueled engines. However, the port methane injection tends to cause knock and limits thermal efficiency gains. In addition, few researches have focused on the power of APC methane-fueled engines. In this study, fundamental experiments are first conducted in a spark ignition methane direct injection engine with compression ratio = 9.6. Strategies such as lean combustion, dilution combustion (increasing argon mole ratio in argon-oxygen mixture), and boosting intake pressure are adopted. Results indicate that lean combustion has a more significant effect in efficiency enhancement under APC compared with air cycle due to the high specific heat ratio of argon. The combination of dilution combustion and boosting intake pressure is a feasible approach to further improve both efficiencies and powers. When argon mole ratio = 85 %, intake pressure = 0.12 MPa, and excess oxygen ratio = 1.37, the highest net indicated thermal efficiency reaches 59.0 % and the indicated mean effective pressure increases a factor of 1.61 than that at argon mole ratio = 79 % and intake pressure = 0.09 MPa. In this case, the ratio of gross indicated thermal efficiency to theoretical thermal conversion efficiency is 90.5 %. Based on thermodynamic calculation, when the ratio of gross indicated thermal efficiency to theoretical thermal conversion efficiency is assumed to be 90 %, a high net indicated thermal efficiency of 65 % is predicted to be obtained at compression ratio = 14.

Machine learning for underground gas storage with cushion CO2 using data from reservoir simulation

Underground natural gas storage (UNGS) is a means to store energy temporarily for later recovery and use. In such storage operations, carbon dioxide (CO2) can be injected as cushion gas to improve the operating efficiency of the working gas and then be permanently stored in the same reservoir. A potential obstacle for widespread use of this technology is that the mixing of the different gases can lead to undesired CO2 production. Herein, we use a two-component flow model to simulate injection and withdrawal periods of methane (CH4) in idealized reservoirs containing CO2. First, we simulate cases with a single well for both CH4 injection and production. From 1200 simulations with systematic variation of reservoir temperature, porosity, permeability, height, and injection time, we find that the reservoir height and permeability have the most significant impact on the production time until the well stream reaches 1% mole fraction of CO2. In another set of simulations, we investigate the impact of well spacing in seasonal gas storage scenarios with separate wells for CH4 injection and production, while CO2 injection occurs from a third well. Based on the simulated data we construct artificial neural networks (ANNs) that describe the relations between the varied input parameters and the production time of CH4, well-block mole fraction and pressure. We conclude that trained and validated ANN models are useful tools to optimize important parameters for UNGS operations, including well positioning, with the aim at maximizing the amounts of delivered gas.

The Effect of Ignition Procedure on Flashback of Hydrogen-Enriched Flames

Abstract The impact of different ignition sequences on the ignition dynamics of CH4-H2 flames in a bluff body burner is investigated at atmospheric conditions. Experiments are performed over a wide range of operating conditions covering pure methane injection (PH0) to pure hydrogen injection (PH100). A perforated plate of total porosity σ=0.17 is positioned at the outlet of the combustion chamber to increase the chamber back pressure and trigger transient flashback during ignition. Time-series of pressure, OH* chemiluminescence and OH-PLIF images of the propagating flame branch are recorded simultaneously to characterize the ignition process. Two ignition procedures are investigated. For ignition procedure A, designated as an early ignition procedure, the spark is initiated before fuel injection. For ignition procedure B, designated as a late ignition, the spark is only activated after the fuel injection. The impact of the fuel air mixing on the final stabilization state is investigated by changing the fuel delivery time (dt) before the initial spark. Three different time delays are considered dt = 1, 3, and 5 s. The final state of the flame is found to be highly sensitive to the selected ignition procedure and increasing dt favors the occurrence of flashback. At constant power, the magnitude of the pressure peak is driven by a competition between the fuel mass flowrate at the moment of ignition and the high reactivity of hydrogen, which shifts the flammability limit toward lower equivalence ratios, hence generating a lower reaction rate. For procedure A, the peak of the chamber over pressure shows a nonmonotonic growth for increasing levels of H2 in the fuel blend, while it linearly increases for procedure B. Experiments are then conducted at a fixed injection flow velocity Ub = 5 m s–1 and fixed laminar burning velocity Sl0=0.25 m s–1 by varying the level of hydrogen enrichment. For procedure A, the over pressure amplitude decreases with increasing the hydrogen enrichment leading to a soft ignition for all CH4-H2 blends. Under ignition procedure B, the amplitude of the over pressure reached during ignition is found to be relatively unaffected by the hydrogen concentration, but the flame stabilization mode shows a strong dependence to both the level of H2-enrichment and fuel delivery time dt. OH* as well as OH-PLIF images reveal that the trajectory of the flame leading point changes as dt increases. The different dynamics of the flame leading points is likely to be the cause the different types of stabilization modes observed.

Impact of engine control variables on low load combustion efficiency and exhaust emissions of a methane-diesel dual fuel engine

A conventional diesel engine when operated in the reactivity-controlled compression ignition (RCCI) combustion strategy faces challenges of high total hydrocarbon (THC) and carbon monoxide (CO) emissions leading to poor combustion efficiency at low engine loads. The oxides of nitrogen (NOx) versus smoke trade-off, encountered in conventional diesel combustion, is replaced by the NOx-THC trade-off in the RCCI operation. This work focuses on addressing the NOx-THC trade-off issue by systematically investigating the effects of engine control variables, such as, fuel injection timing, exhaust gas recirculation (EGR) and intake throttling, on a light duty compression ignition engine running in a methane-diesel dual fuel mode. The engine is operated at a load of 3 bar gross indicated mean effective pressure and at a speed of 1500 rev/min. Based on relationships identified between engine control variables, combustion parameters, emissions and engine performance, a bottom-up approach is used to combine the control variables synergistically to improve the NOx-THC trade-off. A combination of advanced start of injection timing of diesel (−35 degree crank angle (°CA) after top dead centre), 50% premix ratio and 55% EGR levels along with the end of port fuel injection of methane in the middle of the intake stroke (−270°CA), has resulted in a ∼34 percentage points (from 56% to 90%) improvement in combustion efficiency and a ∼9.5 percentage points improvement in thermal efficiency compared to the baseline low load dual fuel operation while maintaining good combustion stability. THC emission is reduced from 105 to ∼25 g/kWh whilst maintaining low levels of NOx (<0.3 g/kWh).

Surface tension effects on cryogenic liquid injection dynamics in supercritical environment

The injection of cryogenic fluids into environments where the prevailing conditions are supercritical in comparison to the critical point of the injected cryogenic fluid is encountered in cryogenic rocket engines, and novel engine architectures such as the recuperated split cycle engine. The physical characteristics of cryogens injected into supercritical environment are rather unclear. While surface tension is usually assumed to be absent/negligible for supercritical fluids, recent experimental research has identified the existence of surface tension and its effects on liquid hydrocarbons in supercritical environment. This research work proposes an alternative computationally simple adaptive surface tension algorithm for the simulation of a liquid injected into supercritical environment. The numerical simulations presented here correspond to single- and binary-specie cases of iquid nitrogen and liquid methane respectively, undergoing phase transition post their injection into supercritical conditions. Following a critical review of related numerical works, this paper begins with a brief explanation of the physics behind the surface tension effect in a binary-fluid interface in which a supercritical fluid is involved and we present why this effect is of relevance to supercritical cryogenic jets? Then, the rationale and specifics of the the new modelling framework based on adaptive surface tension is discussed along with its implications. The results of the numerical simulations of low-temperature vs near-critical temperature iquid nitrogen and liquid methane injection dynamics revealed the drastically different fluid- and thermo-dynamics at play in these two cases. The role of surface tension at these conditions is also explored.

Computational investigation of methanol pre-chamber combustion in a heavy-duty engine

This work explored the potential of methanol pre-chamber combustion (PCC) for heavy-duty engine applications. An optical engine experiment was conducted to visualize the jet flame development. The measured pressure traces and natural flame luminosity images were also used for the validation of three-dimensional computational fluid dynamics simulations. It was demonstrated that the main chamber (MC) combustion was successfully established by the reactive jet issued from the pre-chamber. Compared to methane PCC in our previous study, the distributed reacting jets were significantly thinner, in particular at the learner condition. The active PCC mode, which comprises enrichment of the mixture in the pre-chamber (PC) by means of direct methane injection, was effective in improving the engine performance. However, excessive PC fueling ratio (PCFR) resulted in lower thermal efficiency due to the higher wall heat transfer and combustion losses. In addition, the effects of various PC and piston geometries on the methanol/methane PC combustion were evaluated. The combination of an optimized PC and a flat piston yielded the highest thermal efficiency owing to the relatively lower combustion and wall heat transfer losses. At engine loads higher than 12.5 bar indicated mean effective pressure, exhaust gas recirculation must be implemented to avoid end-gas autoignition and reduce nitric oxides (NOx) emissions. As expected, the increase in (CR) further promoted engine work because of the higher expansion ratio. With CR of 13 and 14, higher thermal efficiency and lower NOx emission were simultaneously achieved under both intermediate and high loads when the engine was operating at the pure methanol PC combustion mode.

Analysis of flame instability in low-emission tower-type gas turbine combustor with multi-stage methane injection

A low-emission tower-type coaxial-staged combustor with a pilot stage, first main stage and second main stage is simulated in this study. The flow field, flame structure, vortex-mixing interaction, and flame instabilities are predicted with large eddy simulation and partially stirred reactor model. Heat radiation is not considered in the simulations. The results show that the maximum of the averaged length and width of the inner recirculation zone are approximately 249.8 and 71.3 mm, respectively. The distributions of the fuel from various stages in the combustor are analyzed based on the respective mixture fractions. The pressure and heat release rate (HRR) in the combustor fluctuate periodically with a frequency of about 373 Hz. Both HRR and pressure fluctuations increase and then decrease with time, and there is a phase difference of 46.1° between them. Due to the combustion instabilities, the flame structures change periodically, including attached flame and lifted V-shaped flame, in one HRR oscillation cycle. Moreover, the swirling flame length also varies periodically with time. As the pilot stage and first main stages are turned-off, the frequency of HRR fluctuations and pressure fluctuations, as well as the flame root dynamics, are significantly affected. It is also found that the effects of the fuel ratio of the first and second main stages have a significant influence on the flame root dynamics, e.g., different degrees of flashback observed in different cases.

13C surface characterization of midplane and crown collector probes on DIII-D

A dual collector probe system has been implemented on DIII-D for scrape-off-layer (SOL) impurity transport studies. These experiments injected isotopically enriched methane (13CD4) and sampled the impurities from this extrinsic, primary source with graphite collector probes at the outboard midplane and crown of upper single null L-mode plasmas. Using a stable isotopic mixing model, results suggest that 13C from methane injections prior to these experiments has built up on the walls of DIII-D to act as a secondary, intrinsic source of enriched 13C to the collector probes. This secondary source accounts for nearly 60% of the deposits on the midplane collector probes and nearly 90% of the deposition on the collector probes in the crown. These results lay the foundation for future impurity transport models and suggest that further simulation of impurity transport during the methane injection experiments will require two sources of enriched impurities in order to accurately model the SOL impurity profiles of 13C.

CO2-SR technology using NiBa unsupported catalyst. Isotopic study of cyclic process of CO2 storage and in situ regeneration with CH4

The unsupported NiBa catalyst has been used in the CO2-SR (CO2 Storage and in situ Regeneration with CH4) cyclic technology, which allows the use of CO2 from combustion and CH4 from biogas in order to produce enriched syngas streams. The isotopic study in transient regime, using 13CO2 and CD4 instead of 12CO2 and CH4, respectively, has been performed to discriminate the different carbon and hydrogen sources and the participation of the catalyst in the pathways involved in the whole cyclic process of the integrated capture of CO2 and the regeneration with CH4. The dual functionality of the catalyst showed a high chemical retention capacity of CO2 (around 0.15 mmol CO2·gcat-1) in basic Ni-Ba intermetallic centers together with the regeneration capacity through the injection of methane yielding to H2-containing stream production. During the storage stage, the CO2 adsorption and dissociative decomposition are the main reactions together with Boudouard reaction, whereas in the regeneration step, syngas was formed via chemical CO2 reduction by CH4, besides dry methane reforming.

Application of multicomponent sorption for diffusive transport in numerical simulation of tight reservoirs

One of the main challenges in modeling compositional transport in tight formations is to include the complex interaction of chemical species with rock surfaces. Such interactions result in compositional variations near the surfaces, which can significantly affect the compositional diffusive transport through tight pores.This paper presents the application of the Multicomponent Potential Theory of Adsorption (MPTA) for the fluid compositions in the central and near-wall sorbed layers subject to a wall chemical potential. The two-layer approximation of MPTA is implemented in the diffusive transport simulation that computes the mass transfer driven by fugacity gradient based on the dusty gas model for the central and sorbed layers of pores. This simulator uses a partially implicit formulation to solve the multiphase multicomponent mass transfer equations including the sorbed layer.The main novelty of this paper lies in the detailed analysis of the interplay between fluid components and rock surfaces, which became possible with the two-layer MPTA coupled with multicomponent diffusion. The diffusion simulation for a ternary case of methane, n-butane, and n-decane with the approximate MPTA shows that the sorption and capillary pressure can cause the compositional segregation between the central and sorbed layers. The segregation enhances the rates of methane injection and n-decane production in their counter-current diffusion. Methane (the lightest) is transported deep into the reservoir by diffusing through the central layer while n-decane (the heaviest) is diffused primarily through the sorbed layer. n-Butane (the intermediate) does not show preferential partitioning into either layer, resulting in relatively inefficient transport. In the absence of sorption and capillary pressure, the countercurrent diffusion occurs between methane (the lightest) and n-butane (the intermediate) while n-decane (the heaviest) remains nearly immobile. That is, whether the simulation considers the surface-fluid interactions can substantially affect the compositional transport (e.g., produced fluid composition) through tight porous media.The multicomponent Langmuir model is often used for computing the sorbed excess in micropores. However, results show that the Langmuir model becomes physically inconsistent at high pressures because it predicts a monotonically increasing function of pressure. The new approach developed in this research is sufficiently flexible and reasonably accurate for modeling multicomponent sorption at high pressures.