The objective of this study is to uncover the impact of natural fracture network properties and its interaction on the productivity of a multiwell pad system in an unconventional reservoir setting. The investigation uses a theoretical model to characterize the dynamic fluid leak-off behavior in the naturally fractured reservoirs. The effects of well spacing, the sequence of stimulation, and the timing of stimulation on a well's productivity are studied within the naturally fractured settings.
A field case study from the Permian basin with a characterized and calibrated geo-model is used for the investigation. A complex fracture model to incorporate the impact of variable fracturing fluid leak-off as it propagates is utilized to evaluate the hydraulic fractures geometry. History matched production on the calibrated model serves to elucidate the productive fracture geometry. Further, a boundary element computation technique to predict the stress shadow in zipper and non-zipper scenarios is used to predict the multiwell pad production performance with time.
Most of the natural fractures present in the rock fabric of unconventional reservoirs are mineralized. However, because the fractures form a plane of weakness in the system, when they come under the direct or indirect pressure perturbation from the hydraulic fractures, they are easily sheared. It evident that the production performance for wells is severely impacted by the overall geometry and footprint of the hydraulic fractures in these naturally fractured reservoirs. The dynamic fluid leak-off to the natural fracture and its dilation while propagating the hydraulic fracture has an impact on the subsequent fracturing stages (same well and the offset). The loss of fracturing fluid to the natural fractures affects the productivity of the multiwell system. Well spacing decisions are greatly impacted with the density of natural fracture network and fluid leakoff.
A new workflow is created to calibrate the complex fracture model while incorporating a dynamic fluid loss into the natural fracture network. The unique approach not only serves as a methodology to predict well performance in a multiwell stimulation scenario and history match of production, but also provides a consistent approach to optimize well spacing, stimulation sequencing, and timing of stimulation considering the impact of the natural fracture network.
