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Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems
Get PDFIn the case of unconventional geothermal systems, the thermal conditions are decisive, i.e. heat flux and temperature at a certain depth, and the physical properties of rocks, their susceptibility to fracturing, etc., which should be determined on a local scale. The work carried out was aimed at determining the basic thermal parameters of rocks, i.e.: effusivity, thermal conductivity and diffusivity, basing on tests of samples taken from boreholes, representing selected geothermal structures in Poland. Both high-temperature structures (100-135 °C) recognized up to a depth of about 3,800 m within the Fore-Sudetic Monocline and up to about 3,000 m in the Szczecin Synclinorium and the Leba Elevation, as well as medium-temperature structures (60-90 °C), occurring at depth 2,000- 2,500 m (Warszawa Synclinorium, Lublin Synclinorium), were analyzed. Some samples representing low temperature structures (with temperatures below 60 °C), such as Lublin synclinorium and Podlasie-Lublin elevation from depths from about 1,000 to 1,500 m, were also analyzed. The tests of thermal parameters of rocks coupled with simulations showed, that the formations with the highest mean diffusivity and thermal conductivity values are characterized by the largest thermal penetration depth and smallest temperature drop. The research allowed to conclude that among the examined rocks, the Cambrian sandstones of the Leba Elevation and the Zechstein dolomites of the Fore-Sudetic monocline are characterized by the most appropriate parameters from the point of view of obtaining geothermal energy from the enhanced geothermal systems in Poland.Document Type: Original articleCited as: Labus, K., Labus, M., Leśniak, G. Thermal properties of rocks from deep boreholes in Poland in terms of obtaining geothermal energy from enhanced geothermal systems. Advances in Geo-Energy Research, 2023, 8(2): 76-88. https://doi.org/10.46690/ager.2023.05.0
A fractal effective permeability model for dual-wet porous Media
Get PDFRecent studies have shown that the pores of some unconventional rocks can be categorized into hydrophilic pores that boarded by inorganic minerals such as quartz and hydrophobic pores that within the organic matter. The rock which consists of both hydrophilic and hydrophobic pores shows a dual-wettability behavior. The previously-proposed imbibition transient analysis technique has been applied in characterizing the pore size distribution of the dual-wet rocks by analyzing comparative oil and water imbibition data. On the basis of the determined pore size distribution, a fractal model for estimating effective permeability of the dual-wet rock was proposed. The proposed model, together with the imbibition transient analysis technique, is able to estimate effective permeability of the dual-wet rocks by using imbibition data. The proposed model can also estimate the effective permeability of hydrophilic pores and hydrophobic pores. The proposed model takes injection pressure, wettability behavior and pore size distribution of the dual-wet rock into the consideration. Our sensitivity analyses show that injection pressure affects effective permeability and hydrophobic permeability by controlling the water saturation within hydrophobic pores. The rock with higher volumetric fraction of hydrophilic pores tends to have higher hydrophilic permeability and lower hydrophobic permeability. By keeping the porosity constant, effective permeability decreases as the volumetric fraction of small pores increases.Document Type: Original articleCited as: Shi, Y., Guo, Y., Dehghanpour, H., Song, H. A fractal effective permeability model for dual-wet porous media. Advances in Geo-Energy Research, 2023, 8(2): 100-111. https://doi.org/10.46690/ager.2023.05.0
Effect of drilling and wellbore geometry parameters on wellbore temperature profile: Implications for geothermal production
Get PDFPrediction of the wellbore fluids and formation temperatures is crucial during drilling operation, especially for high temperature wells, such as geothermal applications. This work presents the applications of an improved comprehensive drilling simulator for predicting the wellbore system temperature during the drilling process. A fully transient numerical model of the wellbore temperature is developed for drilling and geothermal production applications. The model describes the dynamic behaviour of the thermal state of the wellbore during circulation and static conditions. The developed model is implemented with the commercial virtual drilling simulator through an application programming interface. This implementation allows the coupling of the thermal model with other physical models, which leads to more advanced and realistic simulations. The model has been previously validated through a direct comparison with field data from geothermal well located in the Hanover area in Germany. The results showed a good agreement between the predicted outlet fluid temperature and the measured one. Furthermore, an analysis of the effect of various parameters on the wellbore system temperature is performed. This analysis showed the impact of these parameters on the wellbore temperature profile including the critical areas such as the casing setting point and bottom hole assembly. This information may lead to enhancing the wellbore stability by monitoring the thermal stresses, especially in high-temperature wells. Moreover, predicting the drill bit temperature can result in increasing the lifetime of the bit by adjusting the operating conditions to keep the bit temperature within the specified range. Based on these results, the enhanced drilling simulator with the transient temperature model showed to be a suitable tool for effective well planning.Document Type: Original articleCited as: Abdelhafiz, M. M., Oppelt, J., Mahmoud, O., Hegele, L. A. Effect of drilling and wellbore geometry parameters on wellbore temperature profile: Implications for geothermal production. Advances in Geo-Energy Research, 2023, 8(3): 170-180. https://doi.org/10.46690/ager.2023.06.0
Factors affecting the fluid temperature of geothermal energy wells converted from abandoned oil and gas wells
Get PDFThe transition from fossil energy to clean energy is an ongoing trend. Because geothermal energy is buried beneath oil and gas wells, it is desirable to convert abandoned oil and gas wells to geothermal energy wells. The candidate wells can be dry holes in oil and gas exploration or end-of-life oil and gas wells in depleted oil and gas reservoirs. There is a knowledge gap to fill between the oil and gas wells and geothermal wells in the well conversion engineering, that is, factors affecting the performance of the geothermal wells are not fully understood. This work investigated the factors affecting the temperature of produced water of geothermal energy wells converted from abandoned oil and gas wells. Both vertical and horizontal well options were considered. The result of the field case study using the data for a well in the Songliao Basin of Northeastern China shows that, without pipe insulation, the temperature of the returned water is very close to that of the injected water, regardless of vertical or horizontal wells. With pipe insulation, the temperature of the returned water in the horizontal well is higher than that in the vertical well. The temperature of the returned water declines quickly as the thermal conductivity of pipe insulation increases in the low-thermal conductivity region. The temperature of the returned water in horizontal wells is affected by the horizontal hole section length for heat transfer. But this effect levels off after about 1,000 m of horizontal hole section is reached, meaning that 1,000 m of horizontal hole section is adequate for heat transfer from the geothermal zone to the injected water. This paper provides an analytical method for the technical feasibility assessment of converting abandoned oil and gas wells to geothermal energy wells.Document Type: Original articleCited as: Zhang, P., Guo, B. Factors affecting the fluid temperature of geothermal energy wells converted from abandoned oil and gas wells. Advances in Geo-Energy Research, 2023, 9(1): 5-12. https://doi.org/10.46690/ager.2023.07.0
A semianalytical model of fractured horizontal well with hydraulic fracture network in shale gas reservoir for pressure transient analysis
Get PDFAccurate construction of a seepage model for a multifractured horizontal well in a shale gas reservoir is essential to realizing the forecast of gas well production, the pressure transient analysis, and the inversion of the postfracturing parameters. This study introduces a method for determining the fracture control region to characterize the flow area of the matrix within the hydraulic fracture network, distinguishing the differences in the flow range of the matrix system between the internal and external regions caused by the hydraulic fracture network structure. The corresponding derivation and solution methods of the semi-analytical seepage model for fractured shale gas well are provided, followed by the application of case studies, model validation, and sensitivity analysis of parameters. The results indicate that the proposed model yields computational results that closely align with numerical simulations. It is observed that disregarding the differentiation of matrix flow area between the internal and external regions of the fracture network led to an overestimation of the estimated ultimate recovery, and the boundary-controlled flow period in typical well testing curves will appear earlier. Because hydraulic fracture conductivity can be influenced by multiple factors simultaneously, conducting a sensitivity analysis using combined parameters could lead to inaccurate results in the inversion of fracture parameters.Document Type: Original articleCited as: Cui, Q., Zhao, Y., Zhang, L., Chen, M., Gao, S., Chen, Z. A semianalytical model of fractured horizontal well with hydraulic fracture network in shale gas reservoir for pressure transient analysis. Advances in Geo-Energy Research, 2023, 8(3): 193-205. https://doi.org/10.46690/ager.2023.06.0
Nanofluid impact on fluid interaction and migration characteristics for enhanced oil recovery in Baikouquan tight glutenite
Get PDFNanofluids have broad prospects in enhancing the oil recovery of reservoirs with low porosity, low permeability, high capillary pressure and low oil recovery. However, the modification effects of nanofluids on tight glutenite reservoirs remain unknown. In this paper, nanofluids with different proportions of silica nanoparticles and sodium dodecyl sulfate were prepared and characterized by zeta potential and particle size distribution. Then, the effects of nanofluids on interfacial tension and reservoir wettability were examined. Next, a computational fluid dynamics method was adopted to further investigate the effects of nanofluids and injection pressure on enhancing oil recovery of the Baikouquan Formation at the pore scale. The experimental results showed that all prepared nanofluids are stable systems with uniform dispersion. The interfacial tension between the nanofluids and oil was reduced by up to 8.01% compared with water, and the reservoir wettability was changed from intermediate-wet to strong hydrophilicity. The simulation results revealed that the water and nanofluid flooding processes could be divided into two stages: the initial channel establishment stage and the channel expansion stage. In the initial stage, the nanofluids hardly showed an enhanced oil recovery effect due to the faster and sharper migration fronts. In the channel expansion stage, the nanofluids clearly showed an enhanced oil recovery effect, as the nanofluids could displace the oil in the relative dead pores during water flooding. After 10 pore volume injection of displacement fluid at an injection pressure of 1 MPa, the oil recovery using NF5 was highest at 76.58%. In addition, a higher injection pressure led to the extraction of relative dead oil at a lower injection pressure near the inlet with a smaller sweep area near the outlet; the effect on recovery has both advantages and disadvantages.Document Type: Original articleCited as: Cao, X., Li, Q., Myers, M., Xu, L., Chen, Q., Tan, Y. Nanofluid impact on fluid interaction and migration characteristics for enhanced oil recovery in Baikouquan tight glutenite. Advances in Geo-Energy Research, 2023, 9(2): 94-105. https://doi.org/10.46690/ager.2023.08.0
Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs
Get PDFCO2 enhanced oil recovery (CO2-EOR) is a key technology for improving the oil recovery of fractured tight reservoirs, and imbibition has been recognized as an important mechanism for oil recovery in low-permeability reservoirs. To clarify the imbibition role and influencing factors during the CO2-EOR process in fractured tight oil reservoirs and also improve the EOR mechanism, a high-temperature and high-pressure CO2 imbibition experiment was performed based on the nuclear magnetic resonance technology. The results show that high pressure and high permeability are beneficial to imbibition efficiency. The salinity of the imbibition fluid is not very sensitive to the imbibition recovery. In addition, the CO2 increases the imbibition speed and can also significantly improve the production rate and oil recovery. It is beneficial to increase the CO2 concentration to shorten the imbibition equilibrium time and enhance oil recovery. According to the results of the nuclear magnetic resonance study, although the nanopore can provide a greater imbibition force, the oil flow resistance is also larger, but CO2 can reduce the flow resistance of oil and be conducive to oil production in smaller pores. The inclusion of imbibition into the research category of CO2-EOR mechanism will be more in line with field practice and more scientific in fractured tight reservoirs, thus providing theoretical support for the development and improvement of the CO2-EOR technology.Document Type: Original articleCited as: Wang, Y., Shang, Q., Guo, J., Zhou, L. Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs. Capillarity, 2023, 7(3): 47-56. https://doi.org/10.46690/capi.2023.06.0
A new semi-analytical flow model for multi-branch well testing in natural gas hydrates
Get PDFThis paper presents a new semi-analytical solution and the related methodology to analyze the pressure behavior of multi-branch wells produced from natural gas hydrates. For constant bottom-hole pressure production, the transient flow solution is obtained by Laplace transforms. The interference among various branches is investigated using the superposition principle. A simplified form of the proposed model is validated using published analytical solutions. The complete flow profile can be divided into nine distinct regimes: wellbore storage and skin, vertical radial flow, linear flow, pseudo-radial flow, composite flow, dissociated flow, transitional flow, improvement flow and stress-sensitive flow. A well’s multi-branch structure governs the vertical radial and the linear flow regimes. In our model, a dynamic interface divides the natural gas hydrates deposit into dissociated and non-dissociated regions. Natural gas hydrates formation properties govern the compositeeffect, dissociated, transitional, and improvement flow regimes. A dissociation coefficient governs the difference in flow resistance between dissociated and non-dissociated natural gas hydrates regions. The dissociated-zone radius affects the timing of these flow regimes. Conversion of natural gas hydrates to natural gas becomes instantaneous as the dissociation coefficient increases. The pressure derivative exhibits the same features as a homogeneous formation. The natural gas hydrates parameter values in the Shenhu area of the South China Sea cause the prominent dissociated flow regime to conceal the later transitional and improvement flow regimes. Due to the maximum practical well-test duration limitation, the first five flow regimes (through composite flow) are more likely to appear in practice than later flow regimes.Document Type: Original articleCited as: Chu, H., Zhang, J., Zhang, L., Ma, T, Gao Y., Lee, W. J. A new semi-analytical flow model for multi-branch well testing in natural gas hydrates. Advances in Geo-Energy Research, 2023, 7(3): 176-188. https://doi.org/10.46690/ager.2023.03.0
CO2 adsorption and separation properties of M-MOF-74 materials determined by molecular simulation
Get PDFThis study simulated the adsorption and separation of CO2 by the metal-organic frameworks material M-MOF-74, established the skeleton model of M-MOF-74 series adsorbent, and calculated the adsorption of CO2 pure component gas and CO2/N2 mixed gas on MMOF- 74 series adsorbent by the grand canonical Monte Carlo method. Among the CO2 adsorption performances of MOF-74 materials with metal centers of Mg, Co, Ni, and Zn, Mg-MOF-74 had the highest CO2 adsorption capacity, adsorption selection coefficient and adsorption heat. When mixed gas was adsorbed, the law of CO2 adsorption was consistent with that of pure CO2 adsorption. The size law of adsorption heat on MOF-74 was similar to that of adsorption amount. Our findings demonstrated that the interaction between the metal-organic framework material and CO2 is greater than that between the material and N2. The interaction between the gas and the MOF-74 series adsorbent was the main factor affecting the adsorption amount, which reveals the strong influence of metal central atoms on the amount of gas adsorption. Our findings provide new ideas for the design of efficient adsorbent materials.Document Type: Original articleCited as: Deng, J., Zhao, G., Zhang, L., Ma, H., Rong, Y. CO2 adsorption and separation properties of M-MOF-74 materials determined by molecular simulation. Capillarity, 2023, 6(1): 13-18. https://doi.org/10.46690/capi.2023.01.0
Combination of sonic wave velocity, density and electrical resistivity for joint estimation of gas-hydrate reservoir parameters and their uncertainties
Get PDFGas-hydrate saturation and porosity are the most crucial reservoir parameters for gas-hydrate resource assessment. Numerous academics have put forward elastic and electrical petrophysical models for calculating the saturation and porosity of gas-hydrate. However, owing to the limitations of a single petrophysical model, the estimation of gas-hydrate saturation and porosity using single elastic or electrical measurement data appears to be inconsistent and uncertain. In this study, the sonic wave velocity, density and resistivity well log data are combined with a Bayesian linear inversion method for the simultaneous estimation of gas-hydrate saturation and porosity. The sonic wave velocity, density and resistivity data of the Shenhu area in the South China Sea are used to estimate the gas-hydrate saturation and porosity. To validate the accuracy of this method, the estimation results are compared with the saturation obtained from pore water chemistry and porosity obtained from density logs. The well log data examples show that the joint estimation method not only provides a rapid estimation of the gas-hydrate reservoir parameters but also improves the accuracy of results and determines their uncertainty.Document Type: Original articleCited as: Zhang, X., Li, Q., Li, L., Fan, Q., Geng, J. Combination of sonic wave velocity, density and electrical resistivity for joint estimation of gas-hydrate reservoir parameters and their uncertainties. Advances in Geo-Energy Research, 2023, 10(2): 133-140. https://doi.org/10.46690/ager.2023.11.0