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AbstractAn Artificial Neural Network surrogate modelling approach was used to optimise CO2 storage into a highly heterogeneous semi- closed saline aquifer which exhibits considerable pressure increase due to injection. The methodology was implemented to minimise the overall field pressure and well bottom-hole pressures, and to maximise the amount of dissolved and trapped CO2 in the storage aquifer. Different realisations of permeability and porosity were stochastically generated to represent the uncertainty in the model. Artificial neural networks were used to reduce the computational time of the optimisation procedure by approximating the objective functions for CO2 storage as surrogates to the expensive solutions of flow by the simulator. A multi- objective evolutionary algorithm was run on these approximators to generate solutions of the multi-objective optimisation's Pareto front. These solutions were compared with the solutions obtained by the computationally expensive optimisation and they were found to give satisfactory results, illustrating that this methodology can be a viable, and low computational cost alternative for optimisation in CO2 storage design.

AbstractThis paper will present results of a numerical modelling study on CO2 migration through abandoned wells. Leakage of CO2 through plugged and abandoned wellbores is one of the major concerns for long-term safety and effectiveness of geologic CO2 sequestration. For risk assessment and mitigation, it is not only important to understand and characterize the potential for CO2 leakage through wellbores but also subsequent CO2 migration beyond the primary sequestration reservoir. Subsequent to the leak, CO2 may take a direct path towards the accessible environment or it may migrate in an indirect stair-stepping manner through wellbores/fractures across multiple, shallow permeable strata. In the later case, identification of leak source and application of mitigation strategies may become a challenge.For this study we use data from a site in Alberta, Canada which has reported natural gas leak at surface. Investigations on origin of the gas and potential gas migration path from the original source to the surface at the analog site show that the gas could be moving through multiple wells and across multiple formations. There are multiple wells at the site which were drilled and abandoned without production casing and are completely open between two hydrocarbon bearing zones creating cross-flow across zones through open wellbores. Our study focuses on the deeper formations and potential for leakage for CO2 injected in deeper formation. A complex numerical fluid-flow model is developed for the site in FEHM, LANL’s porous media fluid-flow simulator. The model explicitly accounts for wellbore details such as abandonment plugs, casing, annulus cement, etc. The model was used to perform long-term simulations of CO2 injection and potential migration through abandoned wells. Numerical simulation results show limited migration of CO2 through abandoned wells. Such detailed simulation would be valuable to develop effective abandonment practices as well as mitigation strategies at CO2 sequestration sites.

AbstractMinimizing the cost of large-scale geologic storage of CO2 is a paramount concern, and consequently many aquifer storage projects may be implemented without a detailed characterization of the target formation. On the other hand, CO2 migration beyond the volume designed for effective trapping is a paramount risk. Thus, inexpensive methods of monitoring the plume movement will be valuable for operators and regulators alike. Unanticipated heterogeneities within the target formation, whether high-permeability channels or low permeability barriers, are one of the most likely causes of migration beyond the design volume. We propose that routine measurements of injection rate and injection pressure in each well can be used to infer the existence of heterogeneities large enough to affect the plume path. We do not seek from these measurements a detailed spatial distribution of permeability in the formation, but merely an indication of features that affect the overall migration path. The advantage of this approach is that these measurements will be acquired routinely, frequently and cheaply in all projects, whereas methods yielding higher resolution (time-lapse seismic surveys, electromagnetic surveys, cross-well seismic, monitoring wells, etc.) are specialized and expensive.We have implemented this idea by combining (i) our previously developed research software (Pro-HMS) which carries out geologically consistent parameter estimation from injection and production data and (ii) a commercial compositional simulator (GEM from CMG) as a forward model which has been tuned to the full physics and phase behavior of the CO2/brine/rock system. In this paper we test the approach on model aquifers that exhibit permeability heterogeneity prescribed by a spatial correlation model. The permeability estimation process is performed within a fully probabilistic framework. We include the noise typical of pressure/rate data from real wells and find that signal of large heterogeneities can still be discerned.

AbstractAn integrated system combined direct air capture (DAC) and greenhouse agriculture is proposed, in which moisture swing adsorption technology is used to concentrate CO2 from the atmosphere and then feed CO2 to the greenhouse. Absorption isotherm study and desorption kinetic study have been achieved in the paper. The results show that the behaviour of membrane conforms to Langmuir model and its capacity reaches to 0.83mol of CO2 per kilogram of sorbent. When the output CO2 concentration of the desorber is around 1000ppm, desorption efficiency increases from 71.3% to 79.6% when the temperature is changed from 25°C to 40°C. Besides, based on the experiment of the uptake kinetics of plants under different light and different light intensity, energy consumption and techno-economic analysis of the system have been carried out.

AbstractThe Gorgon Joint Venture† made the Final Investment Decision (FID) for the Gorgon Project in September 2009. One element of that approval was the decision to proceed with the Carbon Dioxide Injection Project on Barrow Island, whereby CO2 separated from the reservoir gas from the Gorgon and Jansz-Io fields will be injected into a deep sandstone interval beneath Barrow Island.Since FID, the focus has been on delivering the project – this involves preparations for drilling and completing the four different well types, engineering design and procurement of the CO2 pipeline and procurement and manufacture of the CO2 compression system within the LNG plant.In addition to this engineering activity, the subsurface team has continued with improving their knowledge of the injection interval and overlying geology. The focus of this work has been two-fold:1.Deliver work to support the execution decisions, e.g. finalising well locations, well construction design, well completion design, reservoir data gathering plans, etc. In addition work has also been done to prepare for operations, focusing on understanding the behaviour of super- critical CO2 in the full system from the compressor to the reservoir as a basis for developing operations procedures and documents.2.Prepare for long term reservoir and project management; this includes developing a reservoir management plan with emphasis on surveillance data, continuing to develop the monitoring plans for understanding distribution of CO2 in the injection interval and continuing to evaluate and update understanding of subsurface uncertainties.We currently anticipate commissioning of the carbon dioxide injection system contemporaneous with the start-up of the second Gorgon LNG train in 2015. Between now and then the Carbon Dioxide Injection Project will drill and complete 17 wells, install a seven kilometre buried pipeline and associated facilities and construct, install and commission the CO2 compression system.* The Gorgon Joint Venture comprises the Australian subsidiaries of Chevron (47.3 percent), Exxon Mobil (25 percent), Shell (25 percent), Osaka Gas (1.25 percent), Tokyo Gas (1 percent) and Chubu Electric Power (0.417 percent). Chevron Australia is the operator of the Gorgon Project.

AbstractMore research is needed into the behavior of supercritical CO2 injected for storage in underground rocks at high pressure and temperature as a way of reducing emission of greenhouse gases into the atmosphere. Although many past studies have been based on numerical analyses, most of them considered typical two-phase flow properties in the literature, rather than experimental data, or were based on the properties of fluids other than supercritical CO2 and water. We conducted laboratory experiments on two-phase water- CO2 flow in outcrop and boring core rock samples from formations with potential for use as reservoirs for storage of CO2 to determine the capillary pressure and the relative permeabilities of the two fluids in the two-phase flow system. We developed a water- CO2 separator that allows real-time measurement of water drainage from the two-phase flow system and a procedure for stepwise increases of CO2 injection pressure for quick and efficient drainage of water from the system. We used numerical analysis to simulate injection of CO2 into a water-saturated rock and accurately reproduced the data measured in our laboratory experiments. These results allowed us to determine the relative permeabilities of CO2 and water in the potential reservoir rocks. Our methodology may be useful for evaluating potential reservoirs for subsurface CO2 storage in areas with limited information about rock properties.

13th International Conference on Greenhouse Gas Control Technologies, GHGT-13, 14-18 November 2016, Lausanne, Switzerland A calcium looping (CaL) process is a carbon capture technology which utilizes calcium oxide to remove carbon dioxide from the flue gas of a power plant. Like most capture technologies, CaL process has a high energy demand, which reduces power plant efficiency. The energy penalty and the operating and capital costs of the unit can be reduced by increasing the concentration of O2 in the oxidant flow to calciner. In this study, a calciner has been studied with a three dimensional, steady-state, CFB process model. First, the model was validated by test data of the calciner in la Pereda CaL pilot. Next, a 3D model was created for a 200 MWth commercial scale calciner, in which the inlet oxygen concentration was increased up to 75% to map the potentials of improving the heat balance of the system and to investigate how the calciner operates in these conditions. Based on the simulations, the CaL process is feasible even at very high inlet oxygen concentration. The work presented in this paper is being partially funded by the European Commission under the RFCS “CaO2” project. Peer reviewed

AbstractFor a commercial Carbon Capture and Storage (CCS) chain to be successful, it must satisfy a whole range of requirements: technical, economic, environmental, safety, and societal. A comprehensive, understandable and reproducible assessment of CCS projects is a complex task due to several reasons: wide range of actors and factors involved, substantial differences in the type and nature of both actors and factors, and numerous associated uncertainties. In this paper, a standardised methodology is described and illustrated on a few examples of relatively simple case studies. The proposed methodology provides means and tools for evaluation of several economic, environmental, and in the future also risk associated criteria and thereby enables selection of the most promising options for CCS. The methodology will also help to reduce the uncertainty by improving understanding of the most important dependencies and trends for the investigated key performance indicators as enlightened by the case studies examples. It could also help to design efficient incentives and measures to stimulate realization of CCS by identifying and evaluating the most important non-technical factors affecting the CCS chain viability.