A Comprehensive Numerical Model for Simulating Fluid Transport in Nanopores

Abstract

Since a large amount of nanopores exist in tight oil reservoirs, fluid transport in nanopores is complex due to large capillary pressure. Recent studies only focus on the effect of nanopore confinement on single-well performance with simple planar fractures in tight oil reservoirs. Its impacts on multi-well performance with complex fracture geometries have not been reported. In this study, a numerical model was developed to investigate the effect of confined phase behavior on cumulative oil and gas production of four horizontal wells with different fracture geometries. Its pore sizes were divided into five regions based on nanopore size distribution. Then, fluid properties were evaluated under different levels of capillary pressure using Peng-Robinson equation of state. Afterwards, an efficient approach of Embedded Discrete Fracture Model (EDFM) was applied to explicitly model hydraulic and natural fractures in the reservoirs. Finally, three fracture geometries, i.e. non-planar hydraulic fractures, non-planar hydraulic fractures with one set natural fractures, and non-planar hydraulic fractures with two sets natural fractures, are evaluated. The multi-well performance with confined phase behavior is analyzed with permeabilities of 0.01 md and 0.1 md. This work improves the analysis of capillarity effect on multi-well performance with complex fracture geometries in tight oil reservoirs.

A semianalytical model for simulating real gas transport in nanopores and complex fractures of shale gas reservoirs

“…In general, simple fracture geometries such as bi‐wing fractures and orthogonal fracture networks are often modeled using local grid refinement (LRG) to capture the transient flow behavior from matrix to fractures . In recent years, some advanced numerical methods such as unstructured grid, multisegment well approach, and embedded discrete fracture model (EDFM) are developed. However, the above numerical approaches are still challenging to use efficiently due to very complicated gridding issues and an expensive computational cost for unstructured grid method, and complexities in development of computational codes for EDFM preprocessor.…”

A review of stimulated reservoir volume characterization for multiple fractured horizontal well in unconventional reservoirs

“…In addition, virtual cells are added for these fracture segments. The Non-Neighboring Connections (NNCs) are used for these cells to account for fluid transport associated with fractures, including the flow between matrix and fractures, flow inside an individual fracture, and flow between intersecting fractures (Zhang et al, 2017).…”

Embedded Discrete Fracture Models

“…However, to our knowledge, no such validation has been performed for more complex flow phenomena that involve capillarity or gravity. Nevertheless, EDFM has been used in many studies, including that of Panfili and Cominelli [32] to simulate miscible sour gas injection into a fractured carbonate field; Siripatrachai et al [43] and Zhang et al [51] to understand the impact of capillary effects on hydrocarbon production in tight hydraulically fractured formations; Karvounis and Jenny [22] for simulating flow in enhanced geothermal systems; and Shakiba et al [42] to analyze production uncertainties in hydraulic fracture networks characterized by microseismic data.…”