Shale and tight formations are characterized by extraordinarily low permeability (micro- to nano-Darcy) and existence of natural fractures at various scales. Horizontal drilling with multi-stage hydraulic fracturing has enabled commercial oil and gas production from those unconventional resources (UCR). In this paper, we present a simulation study to quantify well interference for shale and tight reservoir development. Specifically, probabilistic hydraulic fracture modeling and reservoir flow simulation are performed to study the lateral well interference with subsurface uncertainty.
In comparison to conventional reservoirs, the probabilistic modeling of UCR presents unique challenges. In addition to petrophysical properties, geomechanical properties play a critical role in hydraulic fracturing. The complexity also lies in the modeling process − hydraulic fracture modeling often needs to be performed prior to reservoir flow simulation. To account for subsurface uncertainty, multiple realizations of model input parameters are considered for both petrophysical and geomechanical properties. Design of Experiments (DoE) are applied at each modeling stage − hydraulic fracture simulation (Planar 3D and Unconventional Fracture Model) to obtain an ensemble of hydraulic fracture networks, and reservoir simulation to generate production forecasting. The ensemble of reservoir models is then calibrated with available production data.
The DoE analysis allows us to systematically quantify the impact of various parameters on both hydraulic fracture and reservoir flow simulations. It is shown that initial water saturation and fracture/matrix compaction tables represent the top-heavy hitters for estimated ultimate recovery (EUR). We then consider two production scenarios (single vs. multiple well production) to quantify the well interference associated with the multiple wells. Additional DoE study revealed that natural fracture is the most crucial factor to impact the well interference. This is because natural fracture density significantly impacts the hydraulic fracture lengths due to the interaction between hydraulic and natural fractures. The well interference results, along with recent field analog data, supported the decision moving from line-drive landing to wine-rack landing to mitigate well interference for the specific formation.