Simulation of tight fluid flow with the consideration of capillarity and stress-change effect

Abstract

The horizontal wells and multi-stage hydraulic fracturing technologies play a significantly important role in developing unconventional reservoirs. Due to the nanopore effects and stress deformation in tight formations, the fluid equilibrium and thermodynamics become more complex and the conventional reservoir simulation models cannot accurately handle these mechanisms. Hence, the objective of this work is to propose a comprehensive simulation model considering the effects of confined space and stress-dependent deformation. We first evaluated the phase envelope and fluid properties in the confined nanopores. Results show that bubble-point pressure and oil viscosity decrease, while formation volume factor and gas-oil ratio increase. The heavy components cause large deviation on the P-T phase envelope at the reservoir condition. Subsequently, a reservoir simulation model of the Bakken tight oil reservoir was built including the effect of stress-dependent deformation. The proposed phase behavior model was applied into the reservoir simulator to predict the hydrocarbon production from the Bakken tight oil reservoir. Finally, the role of the confined space and the stress-dependent deformation on the production are examined in detail. This novel simulation approach can shed light on the better understanding of the key parameters affecting well production of in developing tight oil reservoirs in the future.

Layering in Shales Controls Microfracturing at the Onset of Primary Migration in Source Rocks

“…Fracture propagation in shales has been extensively studied in the context of hydrofracturing for unconventional hydrocarbon production. Studies have mainly focused on the role of heterogeneities, such as pre‐existing fracture planes (Zhang et al, 2019) and layer interfaces on the propagation of hydraulically driven fractures (Haddad & Sepehrnoori, 2015; Guo et al, 2017).…”

Effect of Nanopore Confinement on Fluid Phase Behavior and Production Performance in Shale Oil Reservoir

“…Tang et al established a general reservoir model accounting for the capillary pressure effect to study the well-interference phenomenon. Zhang et al assessed the oil viscosity, oil formation volume factor, and gas–oil ratio considering capillary pressure and combined these fluid properties with a reservoir simulator. Hence, extensive research has been performed to clarify the capillary pressure effect on fluid properties and well production, but studies that consider the effects of adsorption and critical shifts are still rare. , …”