Investigation of Multiple Well Injections for Carbon Dioxide Sequestration in Aquifers
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As the amount of CO2 present in the atmospheres is increasing due to combustion emission, it is becoming more and more important to find ways to reduce greenhouse gas emissions. One of the ways to do that is through carbon sequestration. Saline formations (aquifers) provide viable destination for carbon sequestration. The storage potential in these reservoirs is estimated at several thousands of Giga Tonnes (Gt) of CO2. Even though the capacity is substantial, the process of filling this capacity has a lot of challenges. Injection of large volumes within short period of time increases the formation pressure (which should be below fracture pressure) very fast. For each particular reservoir, injection capacity should be identified based on which CO2 can be injected within a particular injection area and time. In order to achieve this, an in-depth sensitivity study needs to be done on the various reservoir parameters such as thickness, rock compressibility, permeability, porosity, reservoir temperature and pressure, aquifer fracture pressure, number and placement of injection’s wells. The objective of my Master's thesis work is finding ways to increase the storage injection capacity based on reservoir parameters and optimizing the well placement by identifying and developing analytical and numerical tools to do so. The research also focuses on conducting a sensitivity analysis on these parameters in order to find out the optimal injection scenario to obtain the amount of maximum CO2 sequestration in a reservoir. This study can help in the CO2 sequestration capacity predictions and screening suitable reservoir based on technical and economic criteria. In order to derive the injection capacity of the reservoir based on the reservoir parameters, two analytical models of multiple well injections were studied: i) Single-phase (Brine injection in a brine reservoir and ii) Two phase model (CO2 injection in a brine reservoir). In both cases, the aim is to analyse the pressure build-up and the results are discussed in terms of comparison with numerical simulations. Although analytical modeling is less accurate (compare to numerical) and restricted to vertical well injection it allows large number of realizations for sensitivity analysis to find significant patterns of the process and reduces the number of numerical simulations needed at final stages of optimization. Analysis is done by considering infinite acting, homogenous, isotropic and isothermal reservoir condition. The Ei-function approximation method was used to simulate results on pressure profile across the reservoir. Once we have a validated model, we look into increasing the CO2 injection capacity of saline aquifers by applying the multiple wells injection strategy. This was done by looking at the well interferences based on superposition principle and mapping the pressure build-up profile in the reservoir. Various approaches were used to get maximum injection capacity.
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Abhishek Joshi (2014). Investigation of Multiple Well Injections for Carbon Dioxide Sequestration in Aquifers. UWSpace. http://hdl.handle.net/10012/8754