Modeling Well Interference and Optimal Well Spacingin Unconventional Reservoirs Using Fast Marching Method
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2017, Unconventional Resources Technology Conference (URTeC). One of the challenges in the development planning of unconventional reservoirs is determining the potential for well interference. It is essential to understand when and how the well performance has been impacted by surrounding wells as this limits the ultimate recovery from a well. Modeling of well interference in unconventional reservoirs is complicated by the complexity and uncertainties in fracture geometry and the impact of natural fractures. We propose a novel and efficient simulation technique to identify well interference and quantify the impact on well performance in unconventional reservoirs. Our proposed approach relies on the high frequency asymptotic solution of the diffusivity equation leading to the 'Eikonal Equation', which describes the propagation of the pressure front and can be efficiently solved using the Fast Marching Method (FMM) including a detailed description of fracture geometry. Thus, our proposed method serves as a bridge between simplified analytical tools and complex numerical simulation. The well interference time can be quickly estimated and the reservoir can be partitioned accordingly based on the competing pseudo steady state drainage volumes amongst the wells. The transient drainage volume evolution within each PSS subdomain associated with any particular well can be used to recast the 3-D diffusivity equation to a 1-D form which can be solved analytically for pressure and rate response. This method allows us not only to compute rigorously the well drainage volume evolution with time but also to assess the potential impact of neighboring wells. The novelty and advantage of this approach is that it provides an intuitive way to characterize well interference and drainage volume connectivity in the reservoir. We demonstrate the power and versatility of the proposed method using a series of synthetic models. First, a synthetic shale oil reservoir model is used to demonstrate that the FMM can be effectively extended to bounded reservoirs while a series of multi-well scenarios are used to validate the proposed FMM with multi-well drainage volume competition. Next, we apply the above improvements to a large-scale synthetic shale oil model with well interference and performance calculation. Last, we use a simple well spacing optimization example to demonstrate the effectiveness and efficiency of the FMM-based simulation-free workflow.
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Proceedings of the 5th Unconventional Resources Technology Conference
