After gas reservoir put into production, pressure buildup data is easily affected by offset wells. This kind of gas reservoir actually can be regarded as multi-well system. Some gas reservoir has high permeability, and good interwell continuity. The approach presented here can be used as a pre-screening tool for fast initial evaluation of potential injection sites as well as to suggest injection design ideas and optimization of well placement. Good agreement between modeling and reservoir simulations was observed for all cases. Different reservoir properties, such as permeability, formation compressibility as well as vertical size have been considered. The results of modeling were compared with the numerical simulations including single well injection and a variety of cases of multiple well injection, with differing numbers of injectors and their placement. Extension to multiple well injection has been conducted using the superposition principle. The boundaries of a two-phase region, where both CO2 and brine coexist in pores, depend on reservoir and fluid properties and assessed using a single numerical simulation, run to match the analytical solution for pressure distribution, and these values are kept constant when extending to multiple well scenarios. It is based on general 1-D solutions of the diffusivity equation for three regions (CO2, two-phase and brine) established in aquifers when injection is done using a single well. In this paper, a fast semi-analytical approach to evaluate pressure distribution in saline aquifers during multiple well CO2 injection is presented. As such analytical or semi analytical approaches can be very useful. When injection volumes are high, the rate is split between multiple injectors, making the optimization process time consuming for numerical simulations. Therefore, it is very important to determine all parameters which contribute to pressure build up to identify optimal injection design. ![]() ![]() This defines the amount of CO2 to be injected into a reservoir, and is limited by reservoir fracture pressure. One of the key aspects of underground carbon dioxide disposal is the injection rate.
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