A new method to calculate effective permeability of gridblocks used in the simulation of naturally fractured reservoirs

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · SPE Reservoir Engineering

DOI:https://doi.org/10.2118/36730-PA· OSTI ID:527587

Lough, M F; Lee, S H; Kamath, J

Current simulation technology for naturally fractured reservoirs is based on either the continuum or the discrete-fracture approach. The more commonly used continuum model can simulate complex recovery mechanisms. However, it uses a very simplified representation of the fracture system for calculating effective fracture permeability. The discrete-fracture flow method can handle complex fracture geometry. However, its use has been typically limited to basic flow calculations through a connected fracture system embedded in zero-matrix-permeability rock. The authors have developed a new technique for estimating the effective permeability of gridblocks used in conventional simulators. The idea behind this technique is to integrate the realism of fracture systems, as captured by discrete-fracture models, with the complexity of the flow calculations offered by continuum models. The end product of developing this technique is an efficient numerical code based on the boundary-element method. This code permits the fracture system to be complex and poorly connected, and it also includes the contribution from flow through the matrix rock. For fluid flow in the matrix rock, the fractures are treated as planar-source distributions. Periodic boundary conditions, for the flow properties, are used for the calculation of the effective permeability of individual gridblocks. The authors first use a simple fracture system to demonstrate the validity of the method and to evaluate the sensitivity of the results to matrix and fracture properties. They then use fracture statistics data from the Mesaverde sandstone (a tight-gas sand reservoir), effective permeability values from the code, and a continuum simulator to calculate tracer-flow patterns for a more realistic system.

• Sponsoring Organization: USDOE
• OSTI ID: 527587
• Journal Information: SPE Reservoir Engineering, Journal Name: SPE Reservoir Engineering Journal Issue: 3 Vol. 12; ISSN 0885-9248; ISSN SREEEF
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
CALCULATION METHODS
COMPUTERIZED SIMULATION
FRACTURED RESERVOIRS
MATHEMATICAL MODELS
PERMEABILITY
RESERVOIR ROCK
SENSITIVITY ANALYSIS