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We have developed stimulation tests of a model discrete fracture network (DFN) in the Marcellus Shale reservoir, Morgantown, West Virginia. The microseismic response observed from the modeled stage is characteristic of that observed in several stages along the length of the horizontal well, so that the workflow developed in this paper can be easily extended to other stages in this and other Marcellus Shale wells. The model DFN is designed using log data, including fracture image logs from vertical pilot and horizontal wells. Data from these wells provide geomechanical properties, fracture trend and intensity, and stress orientation. Microseismic cluster trends provide additional constraints on geomechanical model development. Results from stimulation tests are used to modify the reservoir DFN and geomechanical model. Modifications ensure consistency with borehole observations. Fractures observed along the length of the horizontal well consist predominantly of one set, whereas two sets are observed in the vertical pilot well. These two sets are required in the model DFN to reproduce the stimulation trend inferred from microseismic data. Northeast asymmetry in the microseismicity associated with hydraulic fracture treatment is interpreted to result from a horizontal drop of [Formula: see text] toward a previously drilled well. The asymmetry is interpreted to result from stress reduction associated with treatment of an earlier parallel well, the presence of a cross-strike structure parallel to the well, or a combination of the two. Limited downward growth, inferred from the microseismic response, required an increase of the minimum stress in model strata underlying the Marcellus.

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Although clustered perforations have become a primary choice of completion for horizontal wells in the development of low-permeability reservoirs, downhole measurements and production logging often indicate nonuniform production from the perforation clusters, with some of them not stimulated or not contributing to the production. One of the mechanisms contributing to this is nonuniform/inefficient breakdown of the perforations. However, being able to assess the effectiveness of perforation breakdown because of lateral variation of the formation properties and stresses is challenging, not only because of the lack of the data, but also because of the lack of a practical engineering model to predict the fracture initiation and breakdown pressures for cased and perforated completions due to the complexity of well configuration and perforation geometry. In this paper, an analytical fracture initiation model is presented along with the comparison against 3D numerical simulations and published experimental data. The breakdown pressure data from a Marcellus shale horizontal test well in the US Department of Energy (DOE)–sponsored Marcellus Shale Energy and Environmental Laboratory consortium are analyzed and compared to the model prediction using the high-resolution 1D mechanical earth model derived from high-tier logs.

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