Geological Porous Media Research Articles

Laboratory study of cyclic underground hydrogen storage in porous media with evidence of a dry near-well zone and evaporation induced salt precipitation

Large-scale storage of ‘green’ hydrogen is essential in our quest to transition to renewable energy sources and achieve the net-zero emission targets. As such, Underground Hydrogen Storage (UHS) in geological porous media, such as in depleted oil and gas fields or saline aquifers, provides a cost-effective solution to store such large volumes of hydrogen (H2) to buffer seasonal fluctuations in renewable energy supply and demand. Due to the novelty of the topic, many research gaps persist, but we focus on H2 transport characteristics in the subsurface, hydrogen recoverability during cyclic operations, chemical interactions, and acoustic velocity as an indicator of H2 saturation. In this study, we investigate UHS using a triaxial core-flooding experiment to address the above-mentioned research gaps by replicating field operations in the laboratory setup at representative subsurface conditions. Unstable displacement due to immiscible two-phase flow led to early H2 breakthrough at 18% of H2 saturation, ultimate H2 saturation of 36% and withdrawal efficiency of 78% during the first cycle. However, cyclic charging and discharging led to an eventual H2 withdrawal efficiency as high as 95%. Observed chemical interactions during our 3-day experiments were negligible, but our results also indicated a strong potential for evaporation-induced salt precipitation after injection of dry H2 gas, leading to decreased reservoir porosity and permeability over time. Our ultrasonic measurements confirmed the sensitivity of P-wave velocity to H2 saturation, which decreased by 3.5% when the H2 saturation increased to 36%. This indicates that H2 plume and leaks in UHS should be possible to monitor using 4D seismic surveys. Our results help to better understand H2 flow, storage, and transport during cyclic UHS. The results indicate that H2 withdrawal efficiency increases as the UHS reservoir matures and provides evidence of a dry near-well zone and evaporation induced salt precipitation in a UHS reservoir.

Static contact angle, interfacial tension, and column height measurements for underground hydrogen storage

Geological porous media are key for large-scale hydrogen (H2) storage and production, where fluid interactions at interfaces and within rock formations are vital for effective gas containment. Although advancements have been achieved in comprehending structural trapping for estimating column height (CH), additional insights are required regarding how pore size impacts this estimation. Currently, CH estimates often consider seal rock potential, without including the capillary contribution from reservoir rock pore for structural trapping capacity assessment. This study measures the static contact angle (CA) on Wolfcamp (WC) Shale and interfacial tension (IFT) under modified drainage and imbibition conditions at temperatures of 30 and 50°C, pressures ranging from 500 to 3000 psia, and a salinity of 10 wt% sodium chloride. Subsequently, the static gas CH was calculated, accounting for contributions from the caprock pores alone and both the caprock and reservoir, to assess the structural sealing capacity of the caprock layer. The experimental procedures are comprehensively detailed in this paper. The outcome indicates that the static CA after drainage for H2)/brine/WC shale rises with pressure as the static CA after imbibition decreases. Both CAs decrease with increasing temperatures. For H2/brine systems, both drainage and imbibition IFTs decline with increasing pressure and temperature. Calculated CHs reveal that lower CAs substantially impact the gas trapping capacity beneath the caprock. In summary, this study highlights the preference for the drainage method in measuring IFT and CA to evaluate the potential structural trapping capacity of injected gas by the overlying caprock.

The Method of Finite Averages: A rigorous upscaling methodology for heterogeneous porous media

Rigorous upscaling techniques offer accurate and computationally-efficient strategies for modeling the average behaviors of multi-physical, multiscale phenomena in geological porous media. However, such techniques often rely on a variety of methodological assumptions that prohibit their rigorous application to practical systems (e.g., systems involving heterogeneous porous media, system-scale boundary conditions, and fine-scale dynamics that are not diffusion-dominant). In this work, we aim to formulate an upscaling methodology with few methodological assumptions to provide high levels of model generality and foster the utilization of rigorously-derived upscaled models in practice. In particular, we introduce the Method of Finite Averages (MoFA), a novel upscaling methodology for rigorously modeling heterogeneous porous media and system-scale boundary conditions. We detail MoFA’s implementation for the advective–diffusive transport of a single species and compare the methodology with classic numerical techniques, as well as other rigorous upscaling techniques, to highlight MoFA’s unique combination of rigor and generality. We then validate the derived model while demonstrating its benefits in three numerical experiments. The results suggest that (1.) the applicability and a priori error guarantees of MoFA models do not directly depend on system geometry, (2.) a model’s applicability and error guarantees can be can arbitrarily expanded and reduced, respectively, with further computational expense, and (3.) downscaling with MoFA provides an efficient strategy for generating accurate pore-scale solutions from upscaled results. Ultimately, the results evidence that upscaled models can be rigorously derived for heterogeneous porous media systems and resolved in a fraction of the time it takes to perform the equivalent pore-scale simulations.

Detection of Iron Disulfide Materials in Geological Porous Media Using Spectral Induced Polarization Method

Summary Iron sulfide (FeS) scale is a known problem that can significantly impact oil and gas (O&G) production. However, current monitoring methods cannot detect the problem at early stages, not until it is too late for any meaningful remedial action. Spectral induced polarization (SIP) is an established geophysical method increasingly used in near-surface environmental applications. The unique characteristics of the SIP method, mainly the sensitivity to both bulk and interfacial properties of the medium, allow for the potential use as a characterization and monitoring tool. SIP is particularly sensitive to metallic targets, such as FeS, with direct implications for the detection, characterization, and quantification of FeS scale. In a column setup, various concentrations of pyrite (FeS2), a common form of FeS scale, within calcite were tested to examine the SIP sensitivity and establish qualitative and quantitative relationships between SIP signals and FeS2 properties. The concentration of FeS2 in the samples directly impacts the SIP signals; the higher the concentration, the higher the magnitude of SIP parameters. Specifically, the SIP method detected the FeS2 presence as low as 0.25% in the bulk volume of the tested sample. This study supports the potential use of SIP as a detection method of FeS2 presence. Furthermore, it paves the way for upcoming studies utilizing SIP as a reliable and robust FeS scale characterization and monitoring method.

The inverse problem of permeability identification for multiphase flow in porous media

Estimating permeability heterogeneity is a key component in modeling multiphase flow in geological porous media such as aquifers and reservoirs. The inverse problem of identifying permeability has been thoroughly studied regarding single-phase flow, however, hardly in two-phase flow problems. In this work, we study the inverse problem of estimating the spatial distribution of permeability in two-phase flow, considering a known saturation distribution, and using an iterative method based on inverting the capillary pressure–permeability relationship. The method is evaluated considering many different problem parameters and shown to be accurate for many cases in both oil–water and CO2–water three-dimensional systems. Large errors are observed when there is significant water trapping due to capillary effects and when conditions are dominated by viscosity. A range of optimal parameters is determined in which the inverse method is most accurate. These parameters can be used in applications, for example, when designing coreflooding experiments for permeability estimation. The estimated permeability is then used to predict the saturation and pressure distributions of two-phase flow with different injection flow rates and fluid fractions. The models are shown to be accurate when permeability estimations are accurate. The results support the possibility of calibrating a numerical model to coreflooding experiments and then using it to replace additional experiments, e.g., for evaluating flow rate effects.

Hydrogen storage in geological porous media: Solubility, mineral trapping, H2S generation and salt precipitation

Hydrogen as a significant energy vector plays an important role in the decarbonization of heavy industry. However, the intermittency and sessional availability of renewable energy sources, as well as the demand for energy at different times and places, require a medium- to long-term storage technology. Underground storage of hydrogen in depleted gas reservoirs and saline aquifers could be a good option given their storage capacity and availability in different geological settings. However, these geological porous media may suffer from many operational, geological, and geochemical complications. This paper attempts to evaluate the geochemical interactions posed by the injection of hydrogen into porous media. The results obtained from a series of thermodynamic and kinetic geochemical modeling calibrated against experimental data show that dissolution of carbonates, anhydrate and halite can occur over time, leading to precipitation of calcite, formation of H2S and long-term closure of the pore structure due to scale formation. The reduction of pyrite to pyrrhotite is likely to occur at a temperature above 90 °C, which may enhance the formation of H2S in the absence of microbial activity. The formation of scale (halite) is a long-term process that only starts after 10 years of operation due to the slow dissolution of halite in porous media. However, during hydrogen injection, salt diffusion, the formation of a dry-out zone and the phenomenon of salting out occur, depending on the salinity and temperature of the formation water. The results of this study can help to better understand and select geological porous media for large-scale hydrogen storage.

Wavelet Transforms for the Simulation of Flow Processes in Porous Geologic Media

Wavelet Transforms for the Simulation of Flow Processes in Porous Geologic Media

Transport of polymer-coated metal–organic framework nanoparticles in porous media

Injecting fluids into deep underground geologic structures is a critical component to development of long-term strategies for managing greenhouse gas emissions and facilitating energy extraction operations. Recently, we reported that metal–organic frameworks are low-frequency, absorptive-acoustic metamaterial that may be injected into the subsurface to enhance geophysical monitoring tools used to track fluids and map complex structures. A key requirement for this nanotechnology deployment is transportability through porous geologic media without being retained by mineral-fluid interfaces. We used flow-through column studies to estimate transport and retention properties of five different polymer-coated MIL-101(Cr) nanoparticles (NP) in siliceous porous media. When negatively charged polystyrene sulfonate coated nanoparticles (NP-PSS-70K) were transported in 1 M NaCl, only about 8.4% of nanoparticles were retained in the column. Nanoparticles coated with polyethylenimine (NP-PD1) exhibited significant retention (> 50%), emphasizing the importance of complex nanoparticle-fluid-rock interactions for successful use of nanofluid technologies in the subsurface. Nanoparticle transport experiments revealed that nanoparticle surface characteristics play a critical role in nanoparticle colloidal stability and as well the transport.

Upscaled Dynamic Relative Permeability for Unstable CO2 Flow in Stratified Porous Media

In geologic porous media, layering is ubiquitous on all length scales ranging from sub-mm compositional laminations to km-thick formations. The current study presents a general framework for estimating the two-phase viscous limit dynamic relative permeability (k_{r} ) for non-communicating stratified sedimentary rocks. The approach is a two-stage upscaling taking into account the influence of nested heterogeneity at intra- and inter-layer scales. Sub-layer heterogeneities, promoting microflow instabilities in individual layers, are modelled by tuning input relative permeability parameters based on the viscosity contrast between fluids. Macroscopic flow instability at the domain scale is tackled by a new analytical solution for the saturation distribution in stratified media considering the complexities of frontal advance theory. For each layer, three flow stages are considered, each with its unique time-dependent behaviour. The overall solution is presented as a set of equations derived by overlapping of the solutions in different layers. The upscaled dynamic k_{r} is figured out by history matching. The practicality of the method is demonstrated in application to measurements collected from the Otway International Research Facility, Victoria, Australia. The results show the significant impact of layer separation on the upscaled endpoint saturations in addition to required modifications on the current k_{r} formulas. A comparison with conventionally modelled steady-state sweep highlights the inadequacy of steady-state upscaling for viscous limit flows. The applicability of the method to estimate k_{r} from the unsteady-state lab experiments conducted on heterogeneous cores is also discussed.

H2−brine interfacial tension as a function of salinity, temperature, and pressure; implications for hydrogen geo-storage

Hydrogen as a clean fuel source compared to hydrocarbons has attracted many attentions to mitigate anthropogenic greenhouse gas emissions and meet global energy demand. However, high volatility and compressibility of hydrogen make a challenge for its storage. In this regard, the surface-based hydrogen storage facilities (e.g. aerospace, cryogenic tanks, high-pressure gas cylinders, etc.) have been in operation for decades. Moreover, H2 geo-storage is an effective way to store vast volume of hydrogen in deep underground formations where it can be withdrawn again to generate energy when the need arises. The interaction between the injected hydrogen and resident formation fluids (e.g. water), can strongly influence the H2-flow pattern and storage capacity. In this regard, interfacial tension (γ) between hydrogen and brine is a key parameter that influences hydrogen displacement within the geological porous medium. As there is a serious lack of literature on this important subject, we measured H2-brine interfacial tension at various geo-storage conditions for a wide range of pressure, temperature, and brine salinity, using the pendant drop technique. The results of the study indicate that γ declined linearly with increasing pressure when temperature and salinity are kept constant. Moreover, a linear reduction in γ with increasing temperature was observed under constant salinity and pressure conditions. The results also clearly demonstrate that γ increased linearly with brine molality over the whole range investigated. An empirical equation was also developed with which γ as a function of pressure, temperature, and brine molality can be predicted. The predictions for data points of this work had a maximum deviation of 2.13% from the experimental data. This work thus provides fundamental data for H2 geo-storage projects, and aids in the implementation of an industrial-scale hydrogen economy.

Three‐Dimensional Permeability Inversion Using Convolutional Neural Networks and Positron Emission Tomography

AbstractQuantification of heterogeneous multiscale permeability in geologic porous media is key for understanding and predicting flow and transport processes in the subsurface. Recent utilization of in situ imaging, specifically positron emission tomography (PET), enables the measurement of three‐dimensional (3‐D) time‐lapse radiotracer solute transport in geologic media. However, accurate and computationally efficient characterization of the permeability distribution that controls the solute transport process remains challenging. Leveraging the relationship between local permeability variation and solute advection behavior, an encoder‐decoder based convolutional neural network (CNN) is implemented as a permeability inversion scheme using a single PET scan of a radiotracer pulse injection experiment as input. The CNN can accurately capture the 3‐D spatial correlation between the permeability and the radiotracer solute arrival time difference maps in geologic cores. We first test the inversion accuracy using synthetic test datasets and then test the accuracy on a suite of experimental PET imaging datasets acquired on four different geologic cores. The network‐predicted permeability maps from the geologic cores are used to parameterize forward numerical models that are directly compared with the experimental PET imaging data. The results indicate that a single trained network can generate robust 3‐D permeability inversion maps in seconds. Numerical models parameterized with these permeability maps closely capture the experimentally observed solute arrival time behavior. This work provides an unprecedented approach for efficiently characterizing multiscale permeability heterogeneity in complex geologic samples.

Study of the Critical Pore Radius That Results in Critical Gas Saturation during Methane Hydrate Dissociation at the Single-Pore Scale: Analytical Solutions for Small Pores and Potential Implications to Methane Production from Geological Media

We examine the critical pore radius that results in critical gas saturation during pure methane hydrate dissociation within geologic porous media. Critical gas saturation is defined as the fraction of gas volume inside a pore system when the methane gas phase spans the system. Analytical solutions for the critical pore radii are obtained for two, simple pore systems consisting of either a single pore-body or a single pore-body connected with a number of pore-throats. Further, we obtain critical values for pore sizes above which the production of methane gas is possible. Results shown in the current study correspond to the case when the depression of the dissociation temperature (due to the presence of small-sized pores; namely, with a pore radius of less than 100 nm) is considered. The temperature shift due to confinement in porous media is estimated through the well-known Gibbs-Thompson equation. The particular results are of interest to geological media and particularly in the methane production from the dissociation of natural hydrate deposits within off-shore oceanic or on-shore permafrost locations. It is found that the contribution of the depression of the dissociation temperature on the calculated values of the critical pore sizes for gas production is limited to less than 10% when compared to our earlier study where the porous media effects have been ignored.

Influence of Grain Size Transition on Flow and Solute Transport through 3D Layered Porous Media

Abstract Soils and other geologic porous media often have contrasting grain size layers associated with a grain size transition zone between layers. However, this transition zone is generally simplified to a plane of zero thickness for modeling assumption, and its influence has always been neglected in previous studies. In this study, an approach combining a deposition process and a random packing process was developed to generate 3D porous media without and with consideration of the transition zone. The direct numerical models for solving the flow and concentration fields were implemented to investigate the influence of the grain size transition on flow and solute transport. Our results showed that although the transition zone occupied 13.6% of the entire layered porous medium, it had little influence on the distribution of flow velocity at the scale of the entire layered porous medium. However, the transition zone had a significant influence on the local flow field, which was associated with the increased spatial variability of velocity and the varied distribution of flow velocity. This varied local flow field could increase the solute residence time and delay the breakthrough time for solute transport. Although using both the advection-dispersion equation (ADE) and the mobile and immobile (MIM) models to fit the breakthrough curves (BTCs) for solute transport through layered porous media resulted in trivial errors, the ADE model failed to capture the influence induced by the local flow field, especially the influence of the transition zone. In contrast, the MIM model was shown to be able to capture the influence of the transition on solute transport. It was found that the mass transfer rate α, a parameter of the MIM model, was significantly improved by the presence of the transition zone, while it decreased as the transition zone fraction increased. Our study emphasized that the transition zone can vary the local flow field at the pore scale, while it has little influence on the hydraulic properties (e.g., hydraulic conductivity) of the macroscale flow field. However, the local flow field varied by the transition zone has a significant influence on solute transport.

Monte Carlo modeling of scintillation detectors for continuous underground radon monitoring

Nuclear simulation methods were applied to two systems that investigate radon transport within geological porous media: a) a laboratory system built to test, under controlled climate conditions, the effect of temperature on radon transport, and b) a field monitoring system comprising gamma and alpha detectors in an abandoned water well. The use of Monte Carlo simulations of NaI and BGO scintillation detectors in continuous underground radon measurements by gamma counting, to estimate the photon flux in the detector volume, is presented.The advantages of shielding side-view NaI detectors were demonstrated for a laboratory system containing ground phosphate rock, including avoiding high counting rates and reducing the effective source volume in radon transport studies. The gross gamma counting procedure was shown to result in a lower uncertainty than spectrometric measurement, by at least a factor of two, despite it being a simpler and more suitable procedure for field measurements.The calculation of simulated source volumes for a BGO detector in a borehole and the measurements in the field support the assumption that the gamma signal comes primarily from radon flowing in the bedrock's air-filled pores. As a practical outcome of this study, positioning the detector a few cm off-center from the borehole's axis increased the gamma counting efficiency; however, measurements in groundwater taken too close to the iron casing had a lower detection efficiency.The conversion factor from the scintillator signal to the radon activity concentration, for the laboratory system, was calculated. Monte Carlo simulations demonstrated the advantages of the gross counting procedures using gamma scintillation detectors in field underground high-frequency radon monitoring.

Pore-scale modelling and sensitivity analyses of hydrogen-brine multiphase flow in geological porous media

Underground hydrogen storage (UHS) in initially brine-saturated deep porous rocks is a promising large-scale energy storage technology, due to hydrogen’s high specific energy capacity and the high volumetric capacity of aquifers. Appropriate selection of a feasible and safe storage site vitally depends on understanding hydrogen transport characteristics in the subsurface. Unfortunately there exist no robust experimental analyses in the literature to properly characterise this complex process. As such, in this work, we present a systematic pore-scale modelling study to quantify the crucial reservoir-scale functions of relative permeability and capillary pressure and their dependencies on fluid and reservoir rock conditions. To conduct a conclusive study, in the absence of sufficient experimental data, a rigorous sensitivity analysis has been performed to quantify the impacts of uncertain fluid and rock properties on these upscaled functions. The parameters are varied around a base-case, which is obtained through matching to the existing experimental study. Moreover, cyclic hysteretic multiphase flow is also studied, which is a relevant aspect for cyclic hydrogen-brine energy storage projects. The present study applies pore-scale analysis to predict the flow of hydrogen in storage formations, and to quantify the sensitivity to the micro-scale characteristics of contact angle (i.e., wettability) and porous rock structure.

Computational Microfluidics for Geosciences

Computational microfluidics for geosciences is the third leg of the scientific strategy that includes microfluidic experiments and high-resolution imaging for deciphering coupled processes in geological porous media. This modeling approach solves the fundamental equations of continuum mechanics in the exact geometry of porous materials. Computational microfluidics intends to complement and augment laboratory experiments. Although the field is still in its infancy, the recent progress in modeling multiphase flow and reactive transport at the pore-scale has shed new light on the coupled mechanisms occurring in geological porous media already. In this paper, we review the state-of-the-art computational microfluidics for geosciences, the open challenges, and the future trends.

The Impact of Atmospheric and Tectonic Constraints on Radon-222 and Carbon Dioxide Flow in Geological Porous Media - A Dozen-Year Research Summary

Long-term monitoring of Rn-222 and CO2 at a depth of several tens of meters at the Sde-Eliezer site, located within one of the Dead Sea Fault Zone (DSFZ) segments in northern Israel, has led to the discovery of the clear phenomenon that both gases are affected by underground tectonic activity along the DSFZ. It may relate to pre-seismic processes associated with the accumulation and relaxation of lithospheric stress and strain producing earthquakes. This approach assumes that the climatic influence on Physico-chemical parameters is limited at depth since its strength decreases with the increase in the thickness of the geological cover. Hence, the monitoring of natural gases in deep boreholes above the water table enables to reduce the climatic-induced periodic contributions, and uncover the residual portion of the signals that seem to be associated, as indicated recently with regional geodynamic processes. The plausible pre-seismic local movement of the two gases at depth, is identified by the appearance of discrete, random, non-cyclical signals, wider in time duration than 20 hours and clearly wider than the sum of the width of the periodic diurnal and semidiurnal signals driven by ambient climatic parameters. These non-cyclical signals may precede, by one day or more, a forthcoming seismic event. Hence, it is plausible to conclude that monitoring of any other natural gas that is present at depth, may show a similar broadening signal and may serve as a precursor too. The necessary technical conditions enabling to distinguish between anomalous signals of gases that may be induced locally by pre-seismic processes at depth, and the relatively low periodic signals that are still established at depth related to external climatic conditions, are presented in detail.

Modelling ground displacement and gravity changes with the MUFITS simulator

Abstract. We present an extension of the MUFITS reservoir simulator for modelling the ground displacement and gravity changes associated with subsurface flows in geologic porous media. Two different methods are implemented for modelling the ground displacement. The first approach is simple and fast and is based on an analytical solution for the extension source in a semi-infinite elastic medium. Its application is limited to homogeneous reservoirs with a flat Earth surface. The second, more comprehensive method involves a one-way coupling of MUFITS with geomechanical code presented for the first time in this paper. We validate the accuracy of the development by considering a benchmark study of hydrothermal activity at Campi Flegrei (Italy). We investigate the limitations of the first approach by considering domains for the geomechanical problem that are larger than those for the fluid flow. Furthermore, we present the results of more complicated simulations in a heterogeneous subsurface when the assumptions of the first approach are violated. We supplement the study with the executable of the simulator for further use by the scientific community.

How boundary slip controls emergent Darcy flow of liquids in tortuous and in capillary pores

Fundamental investigations of how boundary slip relative to the no-slip condition for liquid flow in a set of two distinct idealized pore geometries, i.e., a diverging-converging tortuous pore, in contrast to a straight tube capillary pore, contribute to emergent Darcy flow and flow enhancement are presented. Using steady-state solutions to Navier-Stokes equations, a sensitivity study investigates the role of (a) a large variation in boundary slip reported in the literature, and (b) a large variation in pore-throat sizes found in geologic porous media. Results show that both the pore geometry and their pore-throat sizes contribute to differences over several orders of magnitude in the emergent Darcy flow behavior and the flow enhancement. Tortuous pores contribute to a lower flow enhancement relative to the capillary pores, and while the larger pore throats (i.e., ≥10μm) negligibly enhance flow, it increasingly becomes significant for the micron-size pore throats. From capillary pores, flow enhancement is found to increases linearly in an unlimited manner with an increment in boundary slip relative to the no-slip condition. In contrast, flow enhancement from diverging-converging tortuous pores is found to get limited defined by an asymptote for flows with a larger boundary slip. Capillary pores offer no change in resistance to flow due to boundary slip. In contrast, the very nature of diverging-converging tortuous pore geometry offers growth in drag forces and energy dissipation rate, i.e., an increase in resistance to flow, which contributes to the asymptote or the limited flow enhancement. A set of theoretical models are presented, which can be used to predict the flow enhancement as a function of boundary slip and spatial-scale of pore throats. This study may have implications for predicting flow enhancement and pressure loss during fluid injection or recovery from low permeability geologic reservoirs, and relevant to other engineering applications, e.g., hydraulics in corrugated channels or design of carbon nanotube membranes for desalinization purposes.

Numerical modelling of brittle–ductile transition with the MUFITS simulator

The numerical modelling of flows in geologic porous media, accounting for plastic behaviour of rocks at high temperatures and hydrofracturing at high fluid pressures, is required for a better understanding of hydrothermal and volcanic systems. The investigation of these systems is limited given the lack of reliable and available reservoir simulation software that accounts for complicated rock behaviour at elevated temperatures. In this paper, we present such software as an extension of the MUFITS reservoir simulator. We describe the mathematical model utilised for modelling the permeability changes of elastic and plastic rocks and input data formats to the simulator. We present several application examples related to the modelling of brittle–ductile transition in hydrothermal systems, in particular perturbed with the emplaced degassing magma body, and provide the corresponding simulator input data to facilitate and ease its further usage.