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Xie J.,Beijing Normal University | Xie J.,Hezhou University | Zhang K.-N.,Beijing Normal University | Wang Y.-S.,China Shenhua Coal Liquefaction Co. CSCLC Ordos | And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

A full-chain carbon capture and storage (CCS) demonstration project was implemented in 2010 by injecting 105 tons of super-critical CO2 per annum down into the brine-saturated low-permeability sandstone and carbonate aquifers at depths of more than 1 620 m in the northeastern Ordos Basin, China. Based on the site-specific geology and the observational data, a numerical injection model is developed based on TOUGH2-MP/ECO2N to simulate the on-going injection process and hence evaluate the injection-induced behavior of the multiphase flow system in the reservoirs. The pressure build-up and the dynamics of the CO2 saturation plume are assessed. The results show that the model developed can reproduce well the performance of the storage reservoir. The CO2 plume spreads outward symmetrically in the horizontal plane. The Liujiagou sandstone aquifer is the most favorable reservoir for CO2 storage at this site. After 3 years of consecutive injection of CO2, the CO2 plume front in the Liujiagou unit is located at about 550 m in 3 years after the commencement of the injection. The pore pressure buildup due to injection is slightly less than 15 MPa. The plume in the Liujiagou unit is expected to migrate to around 700 m away from the injection well after 53 years of post-injection. The major storage reservoir is at the depth interval 1690-1699 m, which contributes over 80% of the storage capacity of the entire reservoir system. The contribution of the reservoirs to the total storage capacity descreases with the depth downward. The leakage of CO2 into the seals is negligible (< 0.05%) during the 53 years of simulation period. © 2016, Academia Sinica. All right reserved. Source


Xie J.,Chengdu University of Technology | Xie J.,Beijing Normal University | Zhang K.,Beijing Normal University | Li C.,China Institute of Geo Environmental Monitoring | Wang Y.,China Shenhua Coal Liquefaction Co. CSCLC Ordos
International Journal of Greenhouse Gas Control | Year: 2016

Deep saline aquifers are a promising choice for geological carbon dioxide (CO2) sequestration due to their greater storage capacity compared to other geological storage options. Injectivity and storage capacity are key concerns especially considering injection of CO2 into low-permeability reservoirs. Estimation of the CO2 injectivity and storage capacity was conducted with an analytical method and dynamic numerical modeling for an active demonstration site (Chenjiacun) of CO2 sequestration in the Ordos Basin. The analytical estimate of the mass injectivity of the Liujiagou reservoir is 4.06 × 10−6 kg Pa−1 s−1, which is about 64% of the injectivity of the entire reservoir system, followed by the Shiqianfeng unit, which accounts for some 15.8%. The maximum injection rate for the Liujiagou reservoir was estimated to be roughly 15.1 kg/s, leading to 476,000 t of CO2 injected per year. The maximum injection rates for the other four reservoirs are substantially smaller than that for the Liujiagou reservoir. The injectivity of the Liujiagou reservoir estimated by numerical simulation ranges from 0.7 to 3.0 × 10−6 kg Pa−1 s−1. The injectivity of the Shiqianfeng reservoir was estimated to be from 0.2 to 1.1 × 10−6 kg Pa−1 s−1. The injectivities of the remaining reservoirs (i.e., Shihezi downward) are smaller than 0.6 × 10−6 kg Pa−1 s−1. The maximum injection rate estimated from the numerical simulation is approximately 17 kg/s, leading to 536,000 t storage of CO2, with the injection pressure limited to 1.5 times hydrostatic pressure. The annual CO2 storage capacity of the Chenjiacun site is estimated to be 0.53–0.69 Mt, for a single vertical injection well. About 5 injection wells may be required to deal with the current CO2 emission rate from CSCLC coal liquefaction processes, which is about 3 Mt per year. The injectivity and storage capacity at Chenjiacun are not much smaller than that at In Salah and Ketzin, owing to the relatively great thickness and long perforated interval at Chenjiacun. In order to improve the reservoir injectivity and storage capacity further at Chenjiacun for large-scale CO2 storage in the future, possible injection strategies and reservoir management options include introduction of stimulation measures and water-production wells at approximately 1000 m or even further away from the injection well, as well as using fully penetrating vertical wells with long perforated intervals. © 2016 Elsevier Ltd Source


Gao C.,University of Sichuan | Xie L.-Z.,University of Sichuan | Xie L.-Z.,Low Carbon Technology | Xiong L.,University of Sichuan | Wang Y.-S.,China Shenhua Coal Liquefaction Co. CSCLC Ordos
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

The permeability of rock is apparently dependent on the direction or anisotropic, which is resulted from the rock-forming geological processes. At present, theoretical and experimental studies on directional permeability properties of sandstone remain insufficient, and there is lack of quantitative assessment on the anisotropy of permeability. The transient tests are performed on sandstone from CCUS by orthogonally sampling cores. Experiential results indicate that there exists a power function relation between the permeability and the confining pressure. However, as the confining pressure is increased up to 20 MPa, the difference of permeability inorthogonal direction declines gradually, which shows a convert of permeability from anisotropy to isotropy. The pressure sensitivity of the permeability in the vertical coring samples is generally lower than that in the horizontal ones. Furthermore, a theoretical model is deduced in the Cartesian coordinate for the anisotropic permeability, which can be used to explain the vector properties of rock permeability. The parameter of anisotropy ζk is also proposed on the basis of the standard deviation and then is employed to normalize the heterogeneity of permeability in different reservoir sandstones. It shows that the proposed method is quantitative to describe variations of anisotropy in the seepage field system. © 2016, Academia Sinica. All right reserved. Source


Xie J.,Beijing Normal University | Zhang K.,Beijing Normal University | Hu L.,Beijing Normal University | Pavelic P.,International Water Management Institute | And 2 more authors.
Hydrogeology Journal | Year: 2015

Saline formations are considered to be candidates for carbon sequestration due to their great depths, large storage volumes, and widespread occurrence. However, injecting carbon dioxide into low-permeability reservoirs is challenging. An active demonstration project for carbon dioxide sequestration in the Ordos Basin, China, began in 2010. The site is characterized by a deep, multi-layered saline reservoir with permeability mostly below 1.0 × 10−14 m2. Field observations so far suggest that only small-to-moderate pressure buildup has taken place due to injection. The Triassic Liujiagou sandstone at the top of the reservoir has surprisingly high injectivity and accepts approximately 80 % of the injected mass at the site. Based on these key observations, a three-dimensional numerical model was developed and applied, to predict the plume dynamics and pressure propagation, and in the assessment of storage safety. The model is assembled with the most recent data and the simulations are calibrated to the latest available observations. The model explains most of the observed phenomena at the site. With the current operation scheme, the CO2 plume at the uppermost reservoir would reach a lateral distance of 658 m by the end of the project in 2015, and approximately 1,000 m after 100 years since injection. The resulting pressure buildup in the reservoir was below 5 MPa, far below the threshold to cause fracturing of the sealing cap (around 33 MPa). © 2015 Springer-Verlag Berlin Heidelberg Source


Xie J.,Beijing Normal University | Zhang K.,Beijing Normal University | Hu L.,Beijing Normal University | Wang Y.,China Shenhua Coal Liquefaction Co. CSCLC Ordos | Chen M.,China Shenhua Coal Liquefaction Co. CSCLC Ordos
Greenhouse Gases: Science and Technology | Year: 2015

A carbon dioxide (CO2) capture and storage demonstration project was started in 2010 by injecting around 100 000 tonnes of super-critical CO2 per annum into a set of very low-permeability sandstone at depths of more than 1600 m in the northeastern Ordos Basin, China. Based on the site-specific geology and the observational data, a numerical injection model was developed in order to understand the hydrodynamic behavior of CO2 in the subsurface for evaluating reservoir performance. The results show that the model reasonably described the spreading of the CO2 plume. The Triassic Liujiagou sandstone aquifer is the most favorable storage formation for CO2 sequestration at the site of interest. After three years of injection of CO2, the maximum lateral migration distance of CO2 plume is about 550 m and the pressure build-up is about 13 MPa in the Liujiagou formation for the actual injection simulation. The major storage layer is at depths of 1690-1699 m, which contributes around 80% of injectivity of the entire reservoir system. The leakage of CO2 into the geological seals is negligible (<0.1%) over the entire simulation period. Regardless of the relatively good fit during the calibration period, the model overestimated the pressures associated with the injection thereafter. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd. Source

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