Pressure and Rate-transient Behavior of a Horizontal Well Intercepting Multiple Vertical Fractures within a Fractal Reservoir
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Copyright 2018, Unconventional Resources Technology Conference (URTeC). The most popular (and practical) approach for stimulating low/ultralow permeability reservoirs (such as shale oil and shale gas reservoirs) has followed two main strategies: (1) to drill horizontal wells to maximize the extension of the wellbore (and to minimize the number of wells), and (2) stimulate the horizontal well by multiple hydraulic fracturing treatments, which create a distribution of multiple vertical fractures along the wellbore. The effective reservoir "system" created by a horizontal well intercepting multiple vertical fractures (i.e., the so-called "multi-fractured horizontal well" (or MFHW)) is a challenging system to model for flow diagnosis given three factors: (1) the heterogeneous nature and low/ultralow permeability nature of the reservoir, (2) the geometry of the well and the fractures, and (3) the properties of the petroleum fluids. In this paper, we will address the first two of these points by providing semi-analytical reservoir models to represent the MFHW well case in a fractal reservoir. Our approach is to extend the models for horizontal wells intercepting multiple finite-conductivity vertical fractures in a the fractal reservoir scenario. We have restricted our work in this paper to case of a fractal reservoir with typical (i.e., normal) diffusion, as we believe that this case is more likely in theory and in practice than reservoir models which consider "anomalous diffusion." In this work, we show that the pressure transient response of a "multi-fractured horizontal well" (or MFHW) within a fractal reservoir can exhibit a maximum of four (4) distinct periods of flow: (1) fracture (dominated) flow, (2) early fracture-reservoir interaction, (3) late fracture-reservoir interaction, and (4) reservoir-dominated flow. In addition, we present a discussion on considerations for the use of the "fractal source" function as a point or line source solution. The following contributions are derived from this work: We have developed a solution for the pressure and rate-transient performance behaviors of a horizontal well intercepting multiple vertical fractures within a fractal reservoir, based on the traditional "point-source" scheme for the "fractal source" function. We have identified the need to develop a new scheme to model the transient performance behavior for a well intercepting multiple vertical fractures in fractal reservoirs regardless of the type of diffusion (typical or anomalous) they exhibit.
author list (cited authors)
Valdes-Perez, A. R., Larsen, L., & Blasingame, T. A.
complete list of authors
Valdes-Perez, Alex R||Larsen, Leif||Blasingame, Thomas A