The natural gas in the Marcellus Shale is produced most efficiently through horizontal wells through multi-stage hydraulic fracturing stimulation treatment. Even though advances in technology have unlocked considerable reserves of hydrocarbon, the long-term production behavior of the horizontal well with multiple hydraulic fractures is not well understood. Therefore, it is essential to study and evaluate the impact of the different treatment parameters and formation properties on fracture properties and production performance. The objective of this study is to investigate the impact of the stress shadowing, stage sequencing, and the mechanical properties on gas production from multi-stage hydraulic fractured horizontal well completed in Marcellus Shale.
A commercial hydraulic fracturing software was employed to predict the fracture properties for a multi-stage hydraulic fractured horizontal well in Marcellus Shale. The available information included gamma ray, density, resistivity, and sonic logs as well as the fracture treatment data. Minimum horizontal stress, instantaneous shut-in pressure (ISIP), process zone stress (PZS), and leak off mechanism were obtained from a Diagnostic Fracture Injection Test (DFIT). The predicted treating pressures by the model were matched to field data by adjusting the pipe friction and the number of perforations. The predicted hydraulic fracture properties were then incorporated in a reservoir model (simulator) to predict the gas production. The impact of stress shadowing, treatment size, fracturing sequencing, and formation mechanical properties on fractures properties (fracture half-length and conductivity) and gas production were then investigated.
Stress shadowing was found to impact fracture properties especially, the fracture width. This in turn, resulted in lower gas recovery. The impact of the stress shadowing increases as the treatment size increases and stage spacing decreases. It must be noted that as the treatment size increases and the stage spacing decreases (more stages), the gas recovery will increase due to larger stimulated volume. At the same time, the stress shadowing would have more negative impact on the gas recovery. Additionally, the results indicated that the reduction in fracture width, and as a consequence the reduction in gas recovery, is more significant in sequential fracturing as compared to simultaneous fracturing.