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Alberta is the largest hydrogen producer in Canada using renewable electricity or natural gas decomposition. Renewable energy sources like solar and wind produce excess electricity during the summer but generate less in the winter. Underground hydrogen storage is seen as a promising solution to store this surplus energy during peak seasons for later use in the winter. This paper aims to evaluate the feasibility storing hydrogen in a near-depleted gas reservoir in Edson formation, Alberta, as well as the hydrogen storage capacity.
Field data on geology, reservoir fluids, and production are collected for a selected area in Edson formation, where the current recovery factor for natural gas sits at 82%. A comprehensive reservoir model is built and matched towards a production history since 1980s. Multiple hydrogen storage mechanisms are simulated in this study, including structural trapping, diffusivity, solubility, and permeability hysteresis. Different storage scenarios are proposed as storage strategy such as employing historical top producers, existing producers with better reservoir coverage and producers with preferable elevation distributions. In addition, the timing for converting the natural gas reservoir to hydrogen storage is also analysed where the remaining natural gas is employed as the ideal cushion gas. A new multi-objective sparrow search algorithm is further adopted to maximize the H2 storage capacity and recovery rate through the minimal wells.
Results show that it is feasible to store hydrogen in the depleted gas reservoir. As well injection rate increased, the storage capacity initially increased then stabilized, while the hydrogen recovery rate initially dropped from 47.40% to 34.15%, before increasing again to 39.80%. 7 wells were selected as working wells based on their productivity and location among 29 following wells. Scenario analysis reveals that neither the well highest productivity nor the well located at the top achieved the best recovery rate. Optimization study further confirms that well location, hydrogen injection rate and injection time collectively lead to a highest storage capacity and recovery factor, which is nearly higher 10% than base case. In addition, the difference in hydrogen recovery rate is minimal with and without considering diffusivity and solubility, but cannot be ignored when permeability hysteresis or cushion gas are included.
This research estimates the hydrogen storage feasibility in an actual depleted gas reservoir in Alberta. The findings of this study could potentially pave the way for a more sustainable and efficient energy storage solution. By comparing conventional injection-production schemes, which involve injecting cushion gas and hydrogen into the same wells, with proposed schemes that use different wells for injection and production, a more efficient injection-production strategy is identified. The proposed optimization method provides a feasible approach to prevent local convergence issues and accelerate global convergence, thereby improving the overall effectiveness of the hydrogen storage process.
| Country | Canada |
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